271083916 tekla-15-analysis-manual

Tekla StructuresAnalysis Manual

Product version 15.0

January 2009

© 2009 Tekla Corporation

© 2009 Tekla Corporation and its licensors. All rights reserved.

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TEKLA STRUCTURES 15 3

Contents

Preface ...............................................................................................................7Audience ............................................................................................................................................................. 7

Additional help resources .................................................................................................................................... 7

Conventions used in this guide ........................................................................................................................... 8

Related guides .................................................................................................................................................... 9

1 Getting Started with Analysis................................................................. 11

1.1 Basics ................................................................................................................................................... 11

Following through structural analysis ............................................................................................... 13

Members, elements, and nodes....................................................................................................... 13

1.2 Determining member properties ........................................................................................................... 14

Member analysis type ...................................................................................................................... 16

Member axis location ....................................................................................................................... 17

Analysis member offsets .................................................................................................................. 18

Analysis properties of plates ............................................................................................................ 18

Spanning ................................................................................................................................... 20

Loading ...................................................................................................................................... 20

Analysis offsets of plates ........................................................................................................... 21

Analysis properties of components .................................................................................................. 22

Analysis properties of slab components........................................................................................... 23

Analyzing composite beams ............................................................................................................ 24

Viewing analysis results ............................................................................................................ 25

Manual method - limitations ...................................................................................................... 25

Support conditions ........................................................................................................................... 25

Defining support conditions.............................................................................................................. 26

Design information ........................................................................................................................... 27

Properties of intermediate members ................................................................................................ 28

Defining buckling lengths (columns) ................................................................................................ 29

Effective buckling length ............................................................................................................ 29

Kmode options .......................................................................................................................... 30

1.3 Fine-tuning analysis models ................................................................................................................. 31

Adding intermediate nodes .............................................................................................................. 34

Using rigid links ................................................................................................................................ 35

1.4 Analysis information and settings ......................................................................................................... 37

4 TEKLA STRUCTURES 15

A closer look at the analysis model .................................................................................................. 37

Objects ....................................................................................................................................... 38

Nodes connecting members and elements ............................................................................... 38

Loads in analysis.............................................................................................................................. 39

Load modeling code ......................................................................................................................... 39

Analysis method ............................................................................................................................... 40

2 Loads........................................................................................................ 41

2.1 Basics.................................................................................................................................................... 41

Automatic loads and load groups ..................................................................................................... 42

2.2 Grouping loads...................................................................................................................................... 42

Load group properties ...................................................................................................................... 43

Load group compatibility .................................................................................................................. 43

Working with load groups ................................................................................................................. 44

Checking loads and load groups ............................................................................................... 45

Changing the load group ........................................................................................................... 45

Importing and exporting load groups ......................................................................................... 45

2.3 Load types and properties..................................................................................................................... 45

Load types........................................................................................................................................ 46

Load forms ....................................................................................................................................... 48

Load magnitude................................................................................................................................ 49

Temperature loads and strain .......................................................................................................... 49

2.4 Distributing loads................................................................................................................................... 49

Attaching loads to parts or locations ................................................................................................ 50

Applying loads to parts ..................................................................................................................... 50

Loaded length or area ...................................................................................................................... 52

Modifying load distribution................................................................................................................ 52

2.5 Working with loads ................................................................................................................................ 53

Changing loaded length or area ....................................................................................................... 54

Scaling loads in model views ........................................................................................................... 54

Defining varying wind loads.............................................................................................................. 55

2.6 Load reference...................................................................................................................................... 56

Load Groups... ................................................................................................................................. 56

Create Point Load ............................................................................................................................ 58

Create Line Load.............................................................................................................................. 59

Create Area Load ............................................................................................................................. 60

Create Uniform Load ........................................................................................................................ 61

Create Temperature Load ................................................................................................................ 62

Create Wind Load ............................................................................................................................ 63

3 Analysis and Design ............................................................................... 67


3.1 Analysis model geometry...................................................................................................................... 67

Creating rules to define analysis model geometry ........................................................................... 68

Modifying analysis model geometry ................................................................................................. 70

Connecting or disconnecting parts in analysis ................................................................................. 70

Defining analysis connections of parts............................................................................................. 71

Analysis part properties.................................................................................................................... 72

3.2 Analysis model properties..................................................................................................................... 74

Objects in an analysis model ........................................................................................................... 76

Analysis model filter .................................................................................................................. 77

Member axis..................................................................................................................................... 77

Member end connectivity ................................................................................................................. 78

Defining nodes ................................................................................................................................. 78

Model merging with analysis applications ........................................................................................ 79

Analysis method............................................................................................................................... 80

Seismic analysis............................................................................................................................... 80

Modal analysis ................................................................................................................................. 81

Design codes and methods.............................................................................................................. 82

Design properties ...................................................................................................................... 82

Contents of STAAD.Pro results files and reports ............................................................................. 82

3.3 Load combination ................................................................................................................................. 83

Load combination properties............................................................................................................ 83

Load combination factors ................................................................................................................. 84

Load combination types ................................................................................................................... 84

Creating load combinations.............................................................................................................. 86

Automatic load combination ............................................................................................................. 87

Automatically including loads in combinations ................................................................................. 88

Manual load combination ................................................................................................................. 88

3.4 Working with analysis and design models ............................................................................................ 89

Checking objects contained in an analysis model............................................................................ 90

Adding or removing analysis objects................................................................................................ 90

Showing analysis models and support conditions in model views ................................................... 90

Analysis model status ...................................................................................................................... 93

Running analysis.............................................................................................................................. 93

Viewing analysis results ................................................................................................................... 94

3.5 Analysis and design reference.............................................................................................................. 94

Analysis > Analysis & Design Models... ........................................................................................... 95

New... ............................................................................................................................................... 97

Add selected objects ........................................................................................................................ 99

Remove selected objects ............................................................................................................... 100

Load combinations... ...................................................................................................................... 100

Get results...................................................................................................................................... 101


View Analysis Parts ........................................................................................................................ 102

Reset Geometry for Selected Parts................................................................................................ 102


Preface

Tekla Structures includes complete documentation in an accessible help system. Our online help is a detailed guide to Tekla Structures concepts, tools, commands, and features, with plenty of examples. The documentation is also available in PDF format.

Topics in the Preface are:

• Audience (p. 7)

• Additional help resources (p. 7)

• Conventions used in this guide (p. 8)

• Related guides (p. 9)

AudienceThis guide is aimed at structural engineers, detailers and designers who model, analyze, and design concrete and steel structures.

We assume that you are familiar with the processes of structural engineering.

Additional help resourcesThe following resources also provide information about Tekla Structures:

Web site http://www.tekla.com

E-mail Contact your local helpdesk via e-mail:

Area office E-mail address

China [email protected]

Finland [email protected]


If you believe you have discovered a problem with this software, please report it to your Tekla Structures Reseller using the maintenance request form provided at Help > Tekla on the Web > Maintenance request....

Please send any comments or suggestions about Tekla Structures documentation to [email protected].

Tekla Extranet Anyone with a current maintenance contract can use Tekla Extranet. Register now to get free access to our online discussion forums, hints & tips, software downloads, tutorials, and more.

To register, go to https://extranet.tekla.com. You can also access Tekla Extranet from Tekla Structures by clicking Help > Online Support > Tekla Extranet.

Conventions used in this guideTypefaces We use different typefaces for different items in this guide. In most cases the meaning is

obvious from the context. If you are not sure what a certain typeface represents, you can check it here.

Noteboxes We use several types of noteboxes, marked by different icons. Their functions are shown below:

France [email protected]

Germany [email protected]

India [email protected]

Japan [email protected]

Malaysia [email protected]

Middle East [email protected]

Sweden [email protected]

UK [email protected]

US [email protected]

Area office E-mail address

Convention Usage

Bold Bold indicates the names of keyboard keys.

Bold is also used for general emphasis in text.

Arial bold Any text that you see in the user interface appears in Arial bold. Items such as window and dialog box titles, field and button names, combo box options, and list box items are displayed in this typeface.

Italic bold New terms are in italic bold when they appear in the current context for the first time.

Monospace Extracts of Tekla Structures’s program code, HTML, or other material that you would normally edit in a text editor, appears in monospaced font.

Filenames and folder paths appear in monospace.

Also all the text you enter yourself appears in monospaced font.


Related guidesTekla Structures includes a comprehensive help system in a series of online books. You will also receive a printed installation guide with your Tekla Structures installation DVD.

• Modeling Manual

How to create a physical model.

• Analysis Manual

How to create loads and run structural analysis.

• Detailing Manual

How to create reinforcement, connections, and details.

• Drawing Manual

How to create and edit drawings.

• System Manual

Covers advanced features and how to maintain the Tekla Structures environment.

• TplEd User’s Guide

How to create and edit report and drawing templates.

• SymEd User’s Guide

A tip might introduce a shortcut, or suggest alternative ways of doing things. A tip never contains information that is absolutely necessary.

A note draws attention to details that you might easily overlook. It can also point you to other information in this guide that you might find useful.

You should always read very important notes and warnings, like this one. They will help you avoid making serious mistakes, or wasting your time.

This symbol indicates advanced or highly technical information that is usually of interest only to advanced or technically-oriented readers. You are never required to understand this kind of information.


How to use the SymEd graphical interface to manipulate symbols.

• Installation Troubleshooting Guide

Printed booklet explaining how to install Tekla Structures.

TEKLA STRUCTURES 15 11Getting Started with Analysis

1 Getting Started with Analysis

Introduction This chapter explains how to prepare a Tekla Structures model for structural analysis and design. It includes a general description of the principles of analysis and design and discusses the theoretical basis of the analysis method used in Tekla Structures. This chapter also explains what is included in the analysis model, and how it is included. You will also learn how to define support conditions for parts.

Audience This chapter is for engineers and designers who run structural analysis on concrete and steel structures.

Assumed background

We assume that you have created parts.

Contents This chapter is divided into the following sections:

• Basics (p. 11)

• Determining member properties (p. 14)

• Analysis information and settings (p. 37)

1.1 BasicsIn this section This section presents the basic vocabulary and concepts we use to describe structural analysis

in Tekla Structures. The illustrations below show the analysis concepts and procedures.


Getting Started with Analysis

Physical model A physical model includes the parts you have created using the Model Editor, and information related to them. Each part in the physical model exists in the completed structure.

Load model The load model contains information about loads and load groups. It also contains information about the building code Tekla Structures uses in load combination. To create a load model, see Loads (p. 41).

Analysis model Tekla Structures generates an analysis model of the physical and load models when you run structural analysis. Tekla Structures does the following in order to generate the analysis model:

• Creates nodes and analysis members and elements of the physical parts

• Determines the support conditions for nodes

• Determines the connectivity between the members and nodes

• Distributes loads to members and elements

The analysis model also includes load combinations.

Analysis application

Tekla Structures links with a number of analysis applications and also supports import and export with them in several formats. The analysis application you use to run structural analysis uses data from the analysis model to generate analysis results.

For more information on the analysis applications that you can use with Tekla Structures, visit Tekla Extranet at https://extranet.tekla.com. You can also access Tekla Extranet from Tekla Structures at Help > Online Support > Tekla Extranet.

Parts

Loads

Physical and load models

Node

Loads

Analysis member

Analysis model


Topics Following through structural analysis (p. 13)

Members, elements, and nodes (p. 13)

Following through structural analysisBefore analysis Carry out the following steps before you run structural analysis in Tekla Structures:

1. Create the main load-bearing parts to form the physical model. See Parts. There is no need to detail or create connections at this stage.

2. Set the support conditions for parts and connections, as well as other analysis properties for individual members. See Determining member properties (p. 14).

3. Create the load model. See Loads (p. 41).

4. Define the analysis geometry settings and modify the geometry if needed. See Analysis model geometry (p. 67) and Modifying analysis model geometry (p. 70).

5. Create a new analysis model and define its properties. See Analysis model properties (p. 74) and New... (p. 97).

6. Create load combinations. See Load combinations... (p. 100).

7. Check the analysis model in a Tekla Structures model view. See Showing analysis models and support conditions in model views (p. 90) and Checking objects contained in an analysis model (p. 90).

8. Check the analysis parts and modify their properties if needed. See Analysis part properties (p. 72) and View Analysis Parts (p. 102).

Now you are ready to run the analysis.

See also The following sections discuss the theoretical basis of the analysis method used in Tekla Structures. They also explain what is included in the analysis model, and how it is included.

• Members, elements, and nodes (p. 13)

• A closer look at the analysis model (p. 37)

• Loads in analysis (p. 39)

• Load modeling code (p. 39)

• Analysis method (p. 40)

Members, elements, and nodesMembers Every physical part (beam or column) that you select to include in the analysis model produces

one or more analysis members. A single physical part produces several members if the part intersects with other parts. Tekla Structures splits the part at the intersection points of the member axes.

Tekla Structures analyzes parts using properties in the profile and material catalogs, including user-defined properties. If there are no profile or analysis properties in the catalog, Tekla Structures calculates them using the profile dimensions in the model.

To create accurate analysis models, make sure that connected parts have common reference points, for example, at grid line intersections.



Elements Tekla Structures splits the plates, slabs, and panels that you include in the analysis model into analysis elements, based on their analysis properties and the parts connected to them.

Nodes Nodes connect analysis members and elements. Tekla Structures creates nodes at:

• The ends of members

• The intersection points of member axes

• The corners of elements

The following properties affect the exact location of nodes:

• Part profiles, i.e. neutral axis and orientation

• Part reference lines (see Part position)

• Location of member axes (see Member axis location (p. 17) and Member axis (p. 77))

• Location and shape of elements (see Analysis properties of plates (p. 18))

• Node definition method (p. 78)

To force members to meet in the analysis model, Tekla Structures may need to merge nodes, shift or extend member axes, create rigid links between nodes, ignore minor members, etc.

For more information on where and how Tekla Structures creates nodes, members, and elements, see A closer look at the analysis model (p. 37).

See also Determining member properties (p. 14)

1.2 Determining member propertiesYou can define analysis properties for individual parts, or for an entire analysis model. This section describes the properties of the individual analysis members. To define these, use the Analysis, Loading, Composite, Start releases, End releases, and Design tabs in the part properties dialog boxes, or the Analysis tab in the connection and detail dialog boxes.

The methods used to create a physical model affect the analysis model. Because of this, you may need to try different modeling methods and analysis model properties in order to create an accurate analysis model of a complex physical model.


For more information on using common properties for the parts in an analysis model, see Analysis model properties (p. 74).

Topics Member analysis type (p. 16)

Member axis location (p. 17)

Analysis member offsets (p. 18)

Analysis properties of plates (p. 18)

Analysis properties of components (p. 22)

Analysis properties of slab components (p. 23)

Analyzing composite beams (p. 24)

Support conditions (p. 25)

Defining support conditions (p. 26)

Design information (p. 27)

Properties of intermediate members (p. 28)

Defining buckling lengths (columns) (p. 29)

Fine-tuning analysis models (p. 31)

Some analysis properties of parts are user-defined attributes. For more information, see Fine-tuning analysis models (p. 31).



Member analysis type

Use the Analysis tab in the part properties dialog boxes to define how Tekla Structures handles individual members in the analysis. The following table lists the options.

You can have Tekla Structures show the member analysis type of parts using different colors in the physical model. The Color column lists these colors.

Option Description Color

Default Member can take any type of load.

Columns, beams, and braces are modeled as beam members. Slabs and panels are modeled as shell elements.

Temperature load is available only for beam members.

Light gray

Beam Member can take any load, including temperature.

Dark red

Shell Member can take any load, except temperature. Use to analyze slabs, panels, and plates.

Magenta

Ignore Member ignored in the analysis. Red

Truss Member can only take axial forces, not bending or torsion moments, or shear forces. Usually used for brace members.

Green

Truss - Tension only

Member can only take tensile axial forces, not moments or shear forces. If this member goes into compression, it is ignored in the analysis.

Cyan

Truss - Compression only

Member can only take compressive axial forces, not moments or shear forces. If this member goes into tension, it is ignored in the analysis.

Yellow

Rigid diaphragm Only applies to contour plates and concrete slabs parallel to the global xy plane.

Nodes that belong to a part matching the filter will be connected with rigid links which together affect displacement. For example, you can use column_filter to connect only column nodes to rigid diaphragms.

Blue

Shear wall For rectangular concrete panels and concrete slabs using design codes ACI and BS 8110 only.

Tekla Structures analyzes the concrete panel or slab as a shear wall that does not take any direct loads.

Gray

Plate Same as Shell but plate, membrane, or mat foundation elements are used in the analysis application.

Aqua

Membrane Lime

Mat foundation Pink


For more information on members with the Truss, Tension only, or Compression only setting, see A closer look at the analysis model (p. 37).

To have Tekla Structures indicate the member analysis type of parts in an object group using colors:

1. Click View > Representation > Object Representation....

2. Select the object group.

3. In the Color column, select Color by analysis type.

4. Click Modify.

For more information on object representation and object groups, see Object representation settings and Object groups.


Member axis location

The locations of the member axes of parts define where the analysis members actually meet, and their length in the analysis model. They also affect where Tekla Structures creates nodes. See Members, elements, and nodes (p. 13) and A closer look at the analysis model (p. 37).

Use the Analysis tab in the part properties dialog boxes to define the member axis location of individual parts for analysis purposes. The options are:

Tekla Structures uses the options above for each part when you select the Model default option for the member axis location in the analysis model properties. See New... (p. 97) and Member axis (p. 77).


The analysis application that you use may not support all options.

Option Description

Neutral axis The neutral axis is the member axis for this part. The location of the member axis changes if the profile of the part changes.

Reference axis The part reference line is the member axis for this part. See also Part position.

Reference axis (eccentricity by neutral axis)

The part reference line is the member axis for this part. The location of the neutral axis defines axis eccentricity.

If you select the Neutral axis option, Tekla Structures takes the part location and end offsets into account when it creates nodes. See End offsets. If you select either of the Reference axis options, Tekla Structures creates nodes at part reference points.



Analysis member offsets

Use offsets at the ends of analysis members to shorten or lengthen members in their local x directions, for analysis purposes and to take the eccentricity effects into account.

For example, if a beam only actually spans the clear distance between two supporting columns, you can use offsets to only include the clear distance in the analysis, instead of the distance between the center points of the columns.

Another example is an eccentric connection between a precast concrete column and beam. To take the eccentricity of the load from the beam into account, use the analysis offsets of the beam.

Use the Analysis tab in the part properties or connection dialog boxes to define the offset at each end of a member. The options are:


Analysis properties of plates

When creating an analysis model, Tekla Structures creates analysis elements for contour plates, concrete slabs, and concrete panels.

Use the Analysis, Spanning, and Loading tabs in the appropriate part properties dialog boxes to define how Tekla Structures creates analysis elements.

Option Description

Manual Works like end offsets for parts in the physical model. Enter a positive or negative value in the Dx field. See also End offsets.

Automatic Dx The offset is the distance between the intersection of the parts’ neutral axes and the intersection of the edges of the parts.

Longitudinal member offset

Only applies to connection members and details. Works like the Manual option and a value in the Dx field for parts.


The analysis properties of plates are:

See also Spanning (p. 20)

Loading (p. 20)

Analysis offsets of plates (p. 21)

Design information (p. 27)

Property Description

Type See Member analysis type (p. 16). Set to Shell to create elements in the analysis model.

Plane The plane of the plate on which Tekla Structures creates the elements. The options are:

• Top plane

• Middle plane

• Bottom plane

• Left plane

• Right plane

• Middle plane (of left/right)

The reference points of connected parts must also be in this plane.

Element size The approximate dimensions of the elements, in the local x and y directions of the plate. For triangular elements, the approximate dimensions of the bounding box around each element.

Holes The approximate dimensions of the elements around openings.

Some analysis properties of parts are user-defined attributes. For more information, see Fine-tuning analysis models (p. 31).



SpanningUse the plate spanning properties to define which parts carry loads from plates in slab-to-beam connections and wall-to-column connections:

The spanning settings of the plate determine the spanning of the load. The spanning setting of the load does not affect a load applied to a plate (see also Modifying load distribution (p. 52)).

LoadingThe loading properties allow you to include concrete slabs as loads in the analysis model. The loading properties are:


Spanning The options are:

Single spanning plates carry loads in the direction of the primary axis. Beams or columns parallel to the spanning direction are not connected to the plate, and will not carry the load from plate.

Double spanning plates carry loads along the primary and secondary axes. Beams or columns in both directions will carry the load from plate.

Primary axis direction

Define the direction of the primary axis in one of the following ways:

• Enter 1 in the axis field which is parallel to the primary axis direction.

• Click Parallel to part, and then select the beam in the model that is parallel to the direction.

• Click Perpendicular to part, and then select the beam in the model that is perpendicular to the direction.

Show direction on selected members

A red line indicates the primary spanning direction of the plate carrying the load.


Analysis offsets of platesYou can define analysis offsets for individual corners of contour plates, concrete slabs, and concrete panels in the global x, y, and z directions. Use the Analysis offsets tab in the part’s user-defined attributes dialog box. It includes Node offset fields for 12 corners.

To define analysis offsets for a plate:

1. Run the analysis, or create an analysis model.

2. Click Tools > Inquire > Object and select the plate in the model to query its corner points.


Generate self weight load

The analysis model includes the part weight, for example a deck, as a load even if the part is not otherwise included in the analysis model.

If the part is included in the analysis model, so is its self-weight. The option No works only with the analysis types Ignore and Rigid diaphragm.

List boxes for additional loads

Enter slab live load or additional self-weight (screed, services) using three additional loads with load group name and magnitude. The directions of these loads follow the direction of the load group to which they belong.

Part names Use this filter to ensure that area load from a slab is transferred to the correct parts, for example, beams supporting the slab. Typically you would enter the beam name as the filter value.

Use continuous structure load distribution

Use to assign most of the load to the middle supports on continuous structures.



The Inquire Object dialog box opens, listing the corner indices and coordinates:

3. Double-click the plate in the model to open its properties dialog box.

4. On the Attributes tab, click the User-defined attributes... button to open the attributes dialog box.

5. On the Analysis offsets tab, enter the x, y, and z offsets of each corner in the appropriate field, according to the index of the corner. Use the current length units and separate the x, y, and z values with spaces.

6. Click Modify.

Analysis properties of components

Use the Analysis tab in the connection or detail dialog boxes to define how Tekla Structures handles connections and details in the analysis.

The analysis properties of connections and details are:

You can also modify analysis model geometry by moving analysis part handles. See Modifying analysis model geometry (p. 70).



Analysis properties of slab components

Use the Analysis tab in the Slab generation with polygon plate (61) and Slab generation with points (62) dialog boxes to define the analysis properties of parts created using these components.

The following table lists the analysis properties of slab components. The option you select in the Analysis type list box limits the other properties you can define (see the Only use for column).


Use analysis restraints

Set to Yes to use the analysis properties of the connection or detail in the analysis, instead of the analysis properties of the parts in the connection.

You must also select Yes in the Member end release method by connection list box in the Analysis Model Properties dialog box when you create the analysis model. See Member end connectivity (p. 78).

Member selection Use to associate the analysis properties with each connection part (Primary, 1. secondary, 2. secondary, etc.).

Restraint combination

See Support conditions (p. 25) and Defining support conditions (p. 26).

Support condition

Longitudinal member offset

See Analysis member offsets (p. 18).

Analysis profile Tekla Structures uses this profile in the analysis, instead of the one in the physical model, in order to take the stiffness of the connection or detail into account.

Analysis profile length

This means that in the analysis, Tekla Structures overrides the profile of the part in the physical model, for this length.



Analyzing composite beams

Composite beams consist of a beam and studs, with a concrete slab on top of the beam. You can define the analysis properties of the slabs in composite beams, and define the width of the slab manually or automatically.

To define the properties of the concrete slab in a composite beam:

1. Open the Beam Properties dialog box and go to the Composite tab.

2. Select the Composite beam option in the Composite beam list box.

3. Select a Material and enter the Thickness of the slab.

Property DescriptionOnly use for

Analysis type How Tekla Structures analyzes the slabs.

• Ignore: Slabs are not analyzed.

• Beam: Analyze each slab as a beam.

• Plate: Analyze each slab as a plate.

• Rigid diaphragm: Analyze slabs as a rigid diaphragm.

See also Member analysis type (p. 16).

Beam axis The location of the beam axis. See also Member axis location (p. 17).

Beam

Restraints The support conditions of beam ends. The options are Pinned and Fixed.

Beam

Plate plane The plane on which to create the elements and nodes. If you select Top plane, Tekla Structures creates the elements on the top surface of the slab.

Plate

Element type The shape of the elements. Plate

Element size x and y: The approximate dimensions of the elements, in the local x and y direction of the slab. For triangular elements, the approximate dimensions of the bounding box around each element.

Holes: The approximate size of the elements around openings.

Plate

Filter Nodes that belong to a part matching the filter will be connected to the rigid diaphragm. For example, you can use column_filter to connect only column nodes to rigid diaphragms.

Rigid diaphragm


4. To define the effective slab width:

• Manual method: Select the To the left from the beam and/or To the right of the

beam radio button and enter a value in the field next to these buttons. See also Manual method - limitations (p. 25).

• Automatic method: For the left and right side, select the Automatic, half of span

length divided by radio button and enter a value in the field next to these buttons. When you run the analysis, Tekla Structures calculates the effective slab width by dividing the span length of the beam by the value you enter.

See also Viewing analysis results (p. 25)

Viewing analysis resultsTo view the analysis results for composite beams, right-click the beam and select Inquire on the pop-up menu. The analysis results include:

• Element and node IDs

• Effective width

• Slab thickness

• Slab material

• Concrete strength

• Rib width and height

• Stud diameter and length

Manual method - limitations• Effective width cannot exceed the distance to the nearest beam.

• Effective width cannot be more than half the distance to the nearest composite beam.

• If there is no beam on either side of the composite beam, the slab width is zero. Use the Automatic composite beam option to have Tekla Structures calculate the slab width.

Support conditions

In structural analysis, the stresses and deflections of a part depend on how it is supported by, or connected to, other parts. You normally use restraints or springs to model connections. These determine how analysis members move, deflect, warp, deform, etc., in relation to each other, or to nodes.

Member ends and nodes have degrees of freedom (DOF) in three directions. The displacement of a member end can be free or fixed, and the rotation can be pinned or fixed. If the degree of connectivity is between free, or pinned, and fixed, use springs with different elastic constants to model them.

Tekla Structures uses part, connection, or detail properties to determine how to connect members in the analysis model. To define the member end conditions, use the Start releases and End releases tabs in the part properties dialog boxes. The connection and detail dialog boxes have Analysis tabs.

The analysis properties of a member determine the degrees of freedom for each end of a main part or member. The first end of a part has a yellow handle, the second end has a magenta handle. See also Part position.

See also Defining support conditions (p. 26)

Determining member properties (p. 14)



Defining support conditionsParts Use the Start releases and End releases tabs in the part properties dialog boxes to define

support conditions. The Start releases tab relates to the first part end (yellow handle), the End releases tab to the second part end (magenta handle).

Plates To define the support conditions of contour plates, concrete slabs, and concrete panels, use the Supported list box in the Analysis Part Properties dialog box.

Connections and details

Use the Analysis tab in the connection or detail dialog boxes to define the support conditions for the members and node in a connection. Use the Member selection list box to associate the support conditions with each connection part (Primary, 1. secondary, 2. secondary, etc.).

Support conditions

Tekla Structures includes four predefined combinations for member ends, and an option for user-defined settings. The predefined combinations (the first four in the following table) automatically set the appropriate support conditions and degrees of freedom. The combinations are:

The support conditions of a member end can be:

Combination

Support condition

Translational DOFs

Rotational DOFs

Supported Fixed Fixed

Supported Fixed Pinned

Connected Fixed Fixed

Connected Fixed Pinned

Use this option to define your own settings for the supports and connections at member ends. You can use springs and almost any combination of degrees of freedom.

To ensure that the part remains stable, and that all loads applied to it pass through to the other structures, avoid using combinations with too many degrees of freedom.


Displacements and rotations

’U’ denotes translational degrees of freedom (displacement). ’R’ denotes rotational degrees of freedom (rotation). Define the degrees of freedom in the global coordinate system. The options are:

See also Support conditions (p. 25)

Determining member properties (p. 14)

Analysis part properties (p. 72)

Design information

Use the Design tab in the part properties dialog boxes to view and modify the design properties of individual parts in an analysis model. Design properties are properties which can vary, according to the design code and the material of the main part (for example, design settings, factors, and limits).

Option Description

Connected Member end is connected to an intermediate analysis node (another part).

Indicate degrees of freedom for the node.

Supported Member end is the ultimate support for a superstructure (for example, the foot of a column in a frame).

Indicate degrees of freedom for the support.

Option More information

Free Only applies to translational degrees of freedom.

Pinned Only applies to rotational degrees of freedom.

Fixed

Spring Enter translational and rotational spring constants. The units Tekla Structures uses depend on the program’s unit settings.

Partial release Only applies to rotational degrees of freedom.

Use to specify the degree of connectivity, if it is between fixed and pinned. Enter a value between 0 (fixed) and 1 (pinned).



The properties you see when you first open the dialog box are the properties that apply to the entire analysis model you have selected in the Analysis & Design Models dialog box. See also Design codes and methods (p. 82).

To set different design properties for specific parts, modify the values in the appropriate part properties dialog box.

For example, if the analysis model contains parts with different material grades, define the most common material grade using the analysis model properties. Then change the material grade of specific parts using the appropriate part properties dialog box.

To omit individual members from the design check when you run the analysis, set the following properties to No:

• Steel parts: Check design - Enable design check of member

• Concrete parts: Calculate required area - Enable design check of member


Properties of intermediate members

When creating an analysis model, Tekla Structures may need to produce more than one analysis member for each physical part. This can result in intermediate members and member ends.

Tekla Structures determines the analysis properties of intermediate members as follows:

1. The member analysis type and member axis location of the analysis members are the same as of the original part.


2. The analysis offsets of the part ends apply to the corresponding analysis member ends. Intermediate member ends do not have analysis offsets.

3. The support conditions of all intermediate member ends are Connected. The translational and rotational degrees of freedom are all Fixed. This reflects the nature of the physical part, which is a continuous length.

4. The effective buckling length of each analysis member is K*L. K is the length factor for buckling. L is length, a value described by the Kmode design property. For more information, see Defining buckling lengths (columns) (p. 29).

5. The other design properties are the same for the analysis members as for the original part.


Defining buckling lengths (columns)

Tekla Structures allows you to define buckling lengths for column segments, which represent the building levels. Tekla Structures automatically divides columns into segments at the point where a support in the buckling direction exists, or where the column profile changes.

See also Effective buckling length (p. 29)

Kmode options (p. 30)

Effective buckling lengthEffective buckling length is K*L, where K is the length factor and L is the buckling length. To calculate a part’s effective buckling length:

1. Open the part properties dialog box and go to the Design tab.

2. Select an option for Kmode. For more information about the available options, see Kmode options (p. 30).

3. Enter one or more values in the K - Length factor for buckling field. The number of values you can enter depends on the option you selected in the Kmode field. For multiple values:

• Enter a value for each column segment starting with the lowest segment, and

• Use spaces to separate multiple values:

• You can also use multiplication to repeat factors, for example, 3*2.00.

4. Go to the L - Buckling length field:

• To automatically calculate length values, leave the fields blank.

• To override one or more length values, enter values in the relevant buckling length fields. The number of values you need to enter depends on the option you selected in the Kmode field. You can use multiplication to repeat buckling lengths, for example, 3*4000.

5. Create the analysis model and use the Tools > Inquire > Object command on a part. The Inquire Object dialog box opens and displays the member number and the effective buckling length for each segment:



Kmode optionsUse the Kmode options to define how Tekla Structures calculates buckling lengths. The options are:

Option Description

Physical member L is the length of the column.

Column segment L is the length of one column segment.

Column segment, multiple values

L is the length of one column segment with user-defined factors and lengths for each column segment.

Analytical member L is the length of the member in the analysis model.

Analytical member, multiple values

L is the length of the member in the analysis model with user-defined factors and lengths for each member.


1.3 Fine-tuning analysis modelsSeveral properties and user-defined attributes enable you to control how Tekla Structures creates analysis models.

To modify the user-defined attributes, open the part properties dialog box and click the User-defined attributes... button to open the attributes dialog box.

You can also modify several properties on the Analysis and Analysis (2) tabs of the attributes dialog box:

Use the analysis model geometry settings and analysis properties of parts to define how Tekla Structures creates analysis models. See Analysis model geometry (p. 67) and Analysis part properties (p. 72).



Attribute Description Options/Values

Node offsets Moves the part in the analysis model when members do not meet and are not connected.

Consider longitudinal model offsets

Controls the member longitudinal offsets.

Auto (default) uses the Dx end offset if it extends the beam, or if it shortens the beam and there is a node near the shortened position.

None

Extending only uses the Dx end offset when it extends the beam, and ignores it when it shortens the beam.

Always

No. of split nodes Use to create additional nodes or analyze a beam as straight segments, for example, a curved beam.

See also Adding intermediate nodes (p. 34).

Enter the number of nodes.

Split distances To define additional nodes in the member, enter distances from the part starting point to the node.


Enter distances, separated by spaces, for example:

1000 1500 3000

Curved beam by straight segments

Use to analyze a curved beam as straight segments.

Yes

No

Node merge distance

Merges nodes within the distance specified into a single node.

For example, use this to force truss-type analysis members to meet in the analysis model.

The Keep axis attribute overrides this attribute.

Distance

Design group (optimization)

Defines which design group the part belongs to. Used in optimization.

Member level (z) Sets the same z coordinate for all nodes.

Enter a value for the z coordinate.


Profile Analysis part profile.

You can use different analysis profiles at the start and end of parts if the analysis application you use supports it.

Select a profile from the profile catalog.

To use different profiles at part ends, enter two profiles separated by a pipe character, for example:

HEA120|HEA140

Connect to (part IDs)

Forces or disables connections between the analysis members you specify.

Works with the Connect exclusively attribute.

To enable connections, enter the part ID’s, separated by spaces.

To prevent connection, enter negative part ID’s, separated by spaces.

Connect exclusively Select Yes to connect the part only to the parts defined by the Connect to (part IDs) attribute.

Keep axis Select Yes to fix the location of member axis so that Tekla Structures does not shift the axis when it makes members meet in the analysis model.

For example, use this with the Node merge distance attribute to force truss-type members to meet in the analysis model.

Overrides the Node merge distance attribute.

Rigid link Enables or disables rigid links at the start, mid, and end points of parts.

Use with the Force to centric connection option in the Analysis Model Properties dialog box to specify which parts to use rigid links.

See also Using rigid links (p. 35).

For each point:

0 = disable

1 = enable

For example:

• 0 = no rigid links

• 100 = rigid link at start point

• 111 = rigid links at start, mid, and end point

• 001 = rigid link at end point

Pinned rigid link (to part names)

Connects the part using pinned rigid links to the parts you specify.

Enter the part names, separated by spaces, commas, or semicolons. You can also use wildcards (see Wildcards).

Thickness Analysis plate thickness.

Minimum hole size (to consider)

Use to ignore small openings in plates in the analysis.

Enter the size of the bounding box around the opening.

Short cantilever limit (to remove)

Use to ignore short plate cantilevers in the analysis.

Enter a cantilever length.




See also To find out how to create user-defined attributes, see Adding properties.

A closer look at the analysis model (p. 37)

Analysis offsets of plates (p. 21)

Adding intermediate nodes

Sometimes intermediate nodes are needed along a member, for example in frequency analysis.

To create additional nodes, use the following user-defined attributes on the Analysis tab of the part properties dialog box:

Mesh point IDs (add/remove)

Use to exclude nodes from or include nodes in plate element meshes.

Only nodes created because of connected members or loads can be excluded.

To include nodes, enter the point ID’s, separated by spaces.

To exclude nodes, enter negative point ID’s.

For example:

1203 -1205 -1206

Simple plate Select Yes to create a simpler analysis model of plates, where cuts and openings are not considered.

Trim plate connections

Select No to connect plates using rigid links, without moving nodes.

Select Yes to connect plates by moving plate nodes, instead of using rigid links.

Supported Use to define supports for plates and beams.

You can create supports for the bottom edge of a wall, for all edge nodes of a slab, or for all nodes of a beam. For walls the bottom edge can be inclined.

Simply: only translations are fixed

Fully: both translations and rotations are fixed

Some attributes are only available if you select the Extended clash check checkbox in the Analysis Model Properties dialog box. They are:

• Rigid link

• Node merge distance

• Connect to (part IDs)

• Connect exclusively

• Keep axis

For more information on the Extended clash check, see Creating common nodes (p. 38).



• No. of split nodes

Enter the number of nodes. Tekla Structures gives equal spacing to added nodes.

• Split distances

Enter the distance values from the part starting point. Tekla Structures adds nodes using these distances:

Using rigid links

You can enable or disable rigid links using the Node definition method (p. 78) in the entire analysis model. You can override this setting in specific places:

• If Node definition is Force to centric connection, rigid links are generally not used, but it is possible to force rigid links in specific places.

• If Node definition is Use rigid links, rigid links are used, but it is possible to prevent the use of rigid links in specific places.



To define rigid links, use the user-defined attribute Rigid link in the part properties.

The value of the attribute is a three-digit number of 1’s and/or 0’s.

• 1 = rigid link enabled

• 0 = rigid link disabled

The first digit is the setting for the part start point, the second digit is the setting for all intermediate points between the start and end point, and the third digit is setting for the part end point.

A rigid link is created at a connection between two members if:

• An eccentric connection exists.

• Rigid links are enabled for both parts, either as an analysis model property or user-defined attribute of parts.

Example 1 The node definition method of the analysis model is Force to centric connection. If the Rigid link attribute is not set, there will be no rigid link. To create the rigid link, use the following values of the user-defined attribute Rigid link:

If you are merging nodes of two parts, and you have set the Keep axis attribute to Yes for both parts, Tekla Structures creates a rigid link.


Example 2 The node definition method of the analysis model is Use rigid links. If the Rigid link attribute is not set, there will be rigid links. To disable rigid link between two members, set the attribute for one part only:

1.4 Analysis information and settingsThis section generally discusses the analysis process and describes analysis settings.

Topics A closer look at the analysis model (p. 37)

Loads in analysis (p. 39)

Load modeling code (p. 39)

Analysis method (p. 40)

A closer look at the analysis model

This section gives detailed information on how Tekla Structures creates analysis models of physical models.

For this beam, type in 010. (Rigid link is wanted in mid beam.)

For this brace, type in 100. (Rigid link is wanted at beam start point.)

For this beam, type in 101. (No rigid link is created for intermediate nodes.)



See also Objects (p. 38)

Nodes connecting members and elements (p. 38)

ObjectsTekla Structures ignores the following objects in the analysis, even if you have included them in the analysis model (see Objects in an analysis model (p. 76)):

• Parts and loads that are filtered out (see Analysis model filter (p. 77))

• Component objects (minor parts, bolts, reinforcing bars, etc.)

• Parts with the Ignore setting (see Member analysis type (p. 16))

Truss members Tekla Structures does not split members with the Truss, Tension only, or Compression only setting (truss members) when two or more truss members intersect with a normal member or with another truss member.

To force truss member nodes to meet at the same point, use the user-defined attributes Node merge distance and Keep axis. For more information on user-defined attributes, see Fine-tuning analysis models (p. 31).

Nodes connecting members and elementsTekla Structures first creates analysis nodes:

• On member axes at the ends of parts

• At the intersection points of member axes

• At the corners of elements

Tekla Structures then checks if the analysis members have common nodes.

Creating common nodes

To force Tekla Structures to find parts that clash and create common nodes for them, select Extended clash check checkbox in the Analysis Model Properties dialog box.

If the end points of the parts are within 10 mm of each other, Tekla Structures moves the nodes in the following order:

1. Horizontal parts

2. Other parts

Vertical parts and parts that have the user-defined attribute Keep axis set to Yes do not move. Also, supported nodes are not moved.

If the part end points are not within 10 mm of each other, Tekla Structures extends each part’s bounding box by 1 mm to find parts that clash.

Other methods Tekla Structures also creates common nodes for members if:

• A connection exists between the members.

• The user-defined attribute Connect to (part IDs) forces the parts to meet.

See also • For more information on user-defined attributes, see Fine-tuning analysis models (p. 31).

• For more information on the nodes, see Defining nodes (p. 78).

Element nodes This is how Tekla Structures creates nodes when plates connect with other parts:

The methods used to create a physical model affect the analysis model. Because of this, you may need to try different modeling methods and analysis model properties in order to create an accurate analysis model of a complex physical model.


Loads in analysis

These are the principles that Tekla Structures follows when it processes loads in the physical model to create analysis model loads.

You define which loads are included in the analysis model. Tekla Structures applies these loads to members and elements, based on each load’s part name or selection filtering criteria, bounding box, and load panel properties. See Applying loads to parts (p. 50) and Modifying load distribution (p. 52).

In load decomposition, the parts to which a load is applied are projected to the load plane. The load is then applied to these parts according to the load panel properties, of which the load’s spanning properties and distance from each part are most important.

Point loads A point load is applied to the nearest node, or member or element location. If the point load is not located directly on any of these, it may either snap to the nearest location or it may be split into several loads, depending on the filtering criteria, bounding box, and load panel properties.

Line loads A line load is transferred to members and elements that are inside the bounding box of the line load, and that match the part name or selection filtering criteria of the load. In special cases the line load may be decomposed to point loads if it is not perpendicular to the part it is applied to. If several members receive the load, the load is distributed based on the length of each member and the distance between the load and member.

Area and uniform loads

Area loads are decomposed to line loads, and in special cases to point loads if they are not perpendicular to the part they are applied to. These decomposed loads are then applied to members and elements. Members inside the bounding box of the load and that match the part name or selection filtering criteria receive the load. Load panel properties, especially single or double spanning and spanning direction, also affect load decomposition.

Nodal load Tekla Structures binds loads to nodes or members in the analysis model. A load is a nodal load if:

• It is between two nodes and the distance to the nearest node is less than 110 mm.

• It is not between two nodes (even outside the member) but inside the bounding box and meets the part name or selection filtering criteria.

Nodal loads do not cause parts to bend.

Member load If a load does not meet the criteria for the nodal load, it is a member load. Member loads lie along the length of the member and cause member deformations.

Other loads Temperature loads are like line loads which affect an entire member. The left, right, top, and bottom surfaces of the member a temperature load affects define the direction of the load.

Load modeling code

Use the Options dialog box to determine the building code and safety factors Tekla Structures uses in load combination.

Connected part Action

Beam Tekla Structures splits the beam and creates nodes in it at the element corners.

Column Tekla Structures creates a node at the column.

Another plate Tekla Structures creates the analysis elements so that the plates have common nodes on the edges of the plates.



1. Click Tools > Options > Options... > Load modeling.

2. Go to the Current code tab.

3. Select the code in the Load modeling code list box.

4. Change load combination factors on the appropriate tab if needed:

5. Click OK.

Analysis method

You can use either the linear (first order), or non-linear (second order, P-delta), analysis method in Tekla Structures. The non-linear method considers the non-linear nature of the geometry. This takes into account major deflections, but not the non-linear nature of materials. Tekla Structures treats materials as linear. See also Analysis method (p. 80).

Tab Description More information

Current code The code to follow in analysis and load combination.

Eurocode The partial safety factors in limit states and reduction factors, for the Eurocode, based on load group types.

Load combination factors (p. 84)

British The partial safety factors in limit states, for the British code, based on load group types.

AISC (US) The partial safety factors in limit states, for the US code, based on load group types.

UBC (US) Uniform building code, American code.

CM66 (F) The partial safety factors in limit states, for the French code for steel structures, based on load group types.

BAEL91 (F) The partial safety factors in limit states, for the French code for concrete structures, based on load group types.

IBC (US) International building code. American code.

ACI American Concrete Institute publication 318.

If you have to change the code during a project, you will also need to change the load group types and check load combinations.

TEKLA STRUCTURES 15 41Loads

2 Loads

Introduction Once you have modeled physical structures by creating parts you can start adding loads. In Tekla Structures, you can create point loads, line loads, area loads with uniform or variable distribution. You can also model temperature, wind, and seismic loads. Either attach loads to specific parts or to locations.

In this chapter This chapter explains how to create and group loads. It also includes a general description of load groups, load types, and load properties. Load reference (p. 56) contains step-by-step instructions for all load commands.

Assumed background

We assume that you have created a Tekla Structures model and have a basic understanding of modeling.


• Basics (p. 41)

• Grouping loads (p. 42)

• Load types and properties (p. 45)

• Distributing loads (p. 49)

• Working with loads (p. 53)

• Load reference (p. 56)

2.1 BasicsThis section presents some Tekla Structures vocabulary and concepts to help you start to model loads.

Load model A load model is the portion of the Tekla Structures model that includes all loads, together with the load group and building code information related to them. Each load in a load model has to belong to a load group. Each load can only belong to one load group. A load group can contain one or more loads.

Load group A load group is a set of loads that are treated alike during load combination. Load groups should contain loads caused by the same action and to which you want to refer collectively. Tekla Structures assumes that all loads in a group:

• Have the same partial safety and other combination factors


Loads

• Have the same action direction

• Occur at the same time and all together

See Grouping loads (p. 42) and Load combination (p. 83).

You need to create load groups because the same action can cause different types of loads, for example, point loads and area loads. See Load types (p. 46). You can include as many loads as you like in a load group, of any load type.

Working with loads

In Tekla Structures, you can attach each load to a part for modeling purposes. You can also create floating loads that are bound to locations rather than parts. See Attaching loads to parts or locations (p. 50).

Use the load’s bounding box and part name filter or a selection filter to define which parts carry the load. See Applying loads to parts (p. 50).

Topics Automatic loads and load groups (p. 42)

Automatic loads and load groupsSelf-weight Tekla Structures automatically calculates the self-weight of structural parts using the density of

the material and the dimensions of the part.

To automatically include the self-weight of parts in load combinations, select the Include self-weight checkbox when you create load combinations. See Creating load combinations (p. 86).

Wind loads Use the Wind load generator (28) tool to define the effects of wind on a structure. See Create Wind Load (p. 63).

Seismic loads To automatically include seismic loads in the x and y directions in load combinations:

1. Define the code to follow in the seismic analysis.

2. Define the load groups to include in the seismic analysis and their factors.

For more information, see Seismic analysis (p. 80).

See also Load combination types (p. 84)

Attaching loads to parts or locations (p. 50)

2.2 Grouping loadsLoad groups should contain loads caused by the same action and to which you want to refer collectively. Tekla Structures assumes that all loads in a group:

• Have the same partial safety and other combination factors

• Have the same action direction

• Occur at the same time and all together

Topics Load group properties (p. 43)

Load group compatibility (p. 43)

Working with load groups (p. 44)


Load group properties

To define the properties of a load group, click the Load groups icon on the Loads and Analysis toolbar to open the Load Groups dialog box. The properties are:

Current When you apply loads in the model, Tekla Structures applies the Current load group. You can only define one load group as Current.

Name Each load group must have a unique name. Use load group names to define the visibility and selectability of loads. For example, you can select, modify, or hide loads based on their load group. See Filtering objects.

Type The type of a load group is the type of action that causes the loads.

Actions causing loads are building code specific. See Load modeling code (p. 39). Most building codes use some or all of the following actions and load group types:

• Permanent, dead, and/or prestressing loads

• Live, imposed, traffic, and/or crane loads

• Snow loads

• Wind loads

• Temperature loads

• Accidental and/or earthquake loads

• Imperfection loads

Direction The direction of a load group is the global direction of the action that causes the loads. Individual loads in a load group retain their own magnitudes in the global or local x, y, and z directions. See also Load magnitude (p. 49).

Load group direction affects which loads Tekla Structures combines in load combination:

• z direction groups are combined with both x and y direction groups.

• x or y direction groups are not combined with each other.

Color Use different colors for different load groups.

See also Load Groups... (p. 56)



Load group compatibility

When Tekla Structures creates load combinations for structural analysis, it follows the building code you select in Tools > Options > Options... > Load modeling. See Load modeling code (p. 39) and Load combination (p. 83).

To accurately combine loads which have the same load group type, you need to identify which load groups:

• Can occur at the same time (are compatible)

• Exclude each other (are incompatible)

Tekla Structures automatically determines and applies the self-weight of parts. See Automatic loads and load groups (p. 42).


Loads

To define load group compatibility, click Load groups icon on the Loads and Analysis toolbar to open the Load Groups dialog box. Enter numbers to indicate compatibility.

Compatibility Compatible load groups can act together or separately. They can actually be one single loading, for example, a live loading that needs to be split in parts acting on different spans of a continuous beam. Tekla Structures then includes none, one, several, or all of the compatible load groups in a load combination.

Incompatibility Incompatible load groups always exclude each other. They cannot occur at the same time. For example, a wind loading from the x direction is incompatible with a wind loading from the y direction. In load combination Tekla Structures only takes into account one load group in an incompatible grouping at a time.



Working with load groups

Use the Load groups dialog box to view, define, modify, and delete load groups. For example, this is where you set load group properties and indicate load group compatibility.

Click the Load groups icon on the Loads and Analysis toolbar to open the dialog box:

Tekla Structures automatically applies basic compatibility facts, such as self-weight being compatible with all other loads, or live loads being compatible with wind load.

Tekla Structures does not combine loads in the x direction with those in the y direction.

Compatibility indicators are all 0 by default. It indicates that Tekla Structures combines the load groups as defined in the building code.

Load group types vary according to the code defined in Tools > Options > Options... > Load modeling. If you have to change the code during a project, you will also need to change the load group types and check load combinations.


Checking loads and load groupsTo find out which load group a load belongs to, select the load in the model and click the Load groups by loads button. Tekla Structures highlights the load group in the dialog box.

To find out which loads belong to a load group, select the load group in the dialog box and click the Loads by load groups button. The associated loads are highlighted in the model.

If you have many loads in the model, you can show the group name and magnitude in the model view by right-clicking a load and selecting Inquire from the pop-up menu. If you have already run the analysis, Tekla Structures also highlights the parts that carry this load.

Changing the load groupTo move a load to a different load group, select the load in the model, then select a load group in the dialog box and click the Change load group button.

Importing and exporting load groupsTo use the same load groups in other models, you can import and export load groups.

• Right-click on a load group in the Load Groups dialog box and select Export... from the pop-up menu to allow the load group to be used in other models.

• Right-click on the load group list in the Load Groups dialog box and select Import... from the pop-up menu to use load groups from another model.

Tekla Structures saves the load group files in the folder you specify, with the extension lgr.

The default load groups are defined in the DefaultLoadGroups.lgr file, located in the ...\TeklaStructures\*version*\environments\*your environment*\system folder.


2.3 Load types and propertiesIntroduction Each load has a type and properties which define it (e.g. magnitude, direction, and distribution).

This section describes the different load types and the properties of each load type.

Use the load properties dialog box to view or modify the properties of a load. Click Analysis > Properties and select a load type to open its properties dialog box.


Loads

Filtering by properties

You can use load types and groups in filters. For example, you can select, modify, or hide loads based on their type and load group. See Filtering objects.

Topics Load types (p. 46)

Load forms (p. 48)

Load magnitude (p. 49)

Temperature loads and strain (p. 49)

See also Grouping loads (p. 42)

Distributing loads (p. 49)

Load types

Tekla Structures includes the following load types:


Uniform load

Area load

Point load

Line loads

Load type Description

Point load A concentrated force or bending moment that can be attached to a part.

Line load A linearly-distributed force or torsion. By default it runs from a point to another point. You can also create a line load with offsets from the points. A line load can be attached to a part. Its magnitude can vary linearly across the loaded length.

Area load A linearly-distributed force bounded by a triangle or quadrangle. You do not have to bind the boundary of the area to parts. Area loads can have openings.

Uniform load A uniformly-distributed force bounded by a polygon. Uniform loads can have openings. You do not have to bind the polygon to parts.


Loads

Load forms

Distributed loads (line and area loads) can have different load forms.

Line load The load form of a line load defines how the load magnitude varies along the loaded length. The options are:

Area load The load form of an area load defines the shape of the loaded area. It can be:

Temperature load • A uniform change in temperature, that is applied to specified parts, and that causes axial elongation in parts.

• A temperature difference between two surfaces of a part that causes the part to bend.

Strain An initial axial elongation or shrinkage of a part.

To ensure that load analysis is correct, use area and uniform loads for loads on floors. For example, when the layout of beams changes, Tekla Structures recalculates the loads to the beams. It will not do this if you use point or line loads on individual beams.

Load type Description

Option Description

The load magnitude is uniform across the loaded length.

The load has different magnitudes at the ends of the loaded length. The magnitude changes linearly between the ends.

The load magnitude changes linearly, from zero at the ends of the loaded length, to a fixed value in the middle of the loaded length.

The load magnitude changes linearly, from zero at one end of the loaded length, through two (different) values, back to zero at the other end.

Option Description

Quadrangular

Triangular


For information on how to define the length or area a load affects, see Loaded length or area (p. 52).

See also Load magnitude (p. 49)

Load magnitude

Load magnitude can occur in x, y, and z directions. The coordinate system is the same as the current work plane, so positive coordinates indicate a positive load direction. See Work plane.

For example, when you create loads perpendicular to sloped parts, shifting the work plane helps you to place loads accurately. See Defining the work area.

Some types of loads can have several magnitude values. For example, the magnitude of line loads may vary along the loaded length. See Load forms (p. 48).

In the load properties dialog boxes, the following letters denote magnitudes of different types:

• P is for a force acting on a position, along a line, or across an area.

• M is for bending moments acting on a position or along a line.

• T is for torsional moments acting along a line.

Temperature loads and strain

Temperature loads can be caused by:

• An increase or decrease in temperature

• A difference in temperature between the top and bottom surfaces of a part

• A difference in temperature between the sides of a part

Temperature changes cause axial elongation or uniform volume expansion in parts.

Different surface temperatures cause parts to bend.

Strain Strain is an initial axial elongation (+) or shrinkage (-) of a part.

To define the temperature loads and strain that affect parts, click Analysis > Properties > Temperature Load... and use the Magnitude tab.

See also Create Temperature Load (p. 62)

2.4 Distributing loadsThis section explains how to attach loads and how to define which parts, or lengths and areas of parts, carry loads.


Loads

Topics Attaching loads to parts or locations (p. 50)

Applying loads to parts (p. 50)

Loaded length or area (p. 52)

Attaching loads to parts or locations

You can attach loads to parts or locations for modeling purposes.

Attaching a load to a part binds the load and the part together in the model. If the part is moved, copied, deleted, etc., it affects the load. For example, a prestressing load moves with the part to which it is attached, and disappears if the part is deleted.

If you do not attach a load to a part, Tekla Structures fixes the load to the position(s) you pick when you create the load.

To attach a load to parts or locations, open the load properties dialog box. On the Distribution tab, select an option in the Load attachment list box:

To define which parts carry a load, see Applying loads to parts (p. 50).

Applying loads to parts

In order to apply loads in the structural analysis model, Tekla Structures searches for parts in the areas that you specify. For each load, you can define the load-bearing parts by name or selection filter, and the search area. To do this, open the load’s properties dialog box and click the Distribution tab.

Option Description

Attach to member Attaches the load to a specific part. If the part is moved, copied, deleted, etc., it affects the load.

Don’t attach The load is not attached but it is considered a floating load. This load is bound to the position you pick when you create the load, not to parts.

If you select the Attach to member option, you must select the part before picking the position for the load.


Load-bearing parts

To define the load-bearing parts by name:

1. In the Load-bearing parts list box:

• Select Include parts by name to define the parts that carry the load.

• Select Exclude parts by name to define the parts that do not carry the load.

2. Enter the part names.

To define the load-bearing parts by selection filter:

1. In the Load-bearing parts list box:

• Select Include parts by filter to define the parts that carry the load.

• Select Exclude parts by filter to define the parts that do not carry the load.

2. Select the selection filter in the second list box.

For more information on selection filters and filtering, see Filtering objects.

Bounding box Use the load’s bounding box to define the area to search for the parts that carry the load. The bounding box is the volume around the load that Tekla Structures searches for load-bearing parts.

Each load has its own bounding box. You can define the dimensions of a bounding box in the x, y, and z directions of the current work plane. The dimensions are measured from the reference point, line, or area of the load. See also Handles (p. 54).

Offset distances from the reference line or area do not affect the size of the bounding box. See Loaded length or area (p. 52).

See also Each load’s load panel properties also affect which parts receive the load. See Modifying load distribution (p. 52).

You can use wildcards when listing the part names. See Wildcards.


Loads

Loaded length or area

If a line, area, or uniform load affects a length or area which is difficult to pick in the model, pick one close to it. Then use the values in the Distances fields in the load properties dialog boxes to pinpoint the length or area. You can shorten or divide the loaded length, and enlarge or reduce the loaded area.

Line load To shorten or divide the length of a line load, enter positive values for a and b.

Area load To enlarge the area an area load affects, enter a positive value for a. To reduce the area, enter a negative value.

Modifying load distribution

By default, Tekla Structures distributes loads using the panel method. To modify the way loads are distributed, modify the properties on the Load panel tab in the load properties dialog box. The properties are:


Spanning Single: in the direction of the primary axis only

Double: along the primary and secondary axes

Primary axis direction If Spanning is set to Single, you can define the primary axis direction by picking a part in the model and setting this option to Parallel to part or Perpendicular to part.

To manually define the primary axis weight when Spanning is set to Double, you must also define the primary axis direction.

Automatic primary axis weight

Yes: Tekla Structures automatically calculates the load portions for primary and secondary directions.

No: Enter the weight for the primary direction in the Weight field. Tekla Structures calculates the weight for the secondary direction by subtracting this value from 1.


Example When using double spanning, automatic primary axis weight and the weight value affect the proportions of the load which is applied to the primary axis and to the perpendicular axis.

• If Automatic primary axis weight is Yes, the proportions will be in proportion to the third power of the span lengths in these two directions, i.e. the shorter the span, the bigger the proportion of the load. The Weight value does not matter.

• If Automatic primary axis weight is No, the given Weight value (0.50 in this example) is used to divide the load.

2.5 Working with loadsTo modify the properties of a load, double-click it in the model to open the relevant load properties dialog box.

When you have finished, click Modify to update the properties of the load in the model.

Topics Changing loaded length or area (p. 54)

Scaling loads in model views (p. 54)

Defining varying wind loads (p. 55)

Load dispersion angle The angle by which the load is projected onto the surrounding elements.

Use continuous structure load distribution

Yes: for uniform loads on continuous slabs. For the first and last spans, the distribution of support reactions is 3/8 and 5/8, instead of 1/2 and 1/2.

No



Loads

Changing loaded length or area

As well as changing load properties, you can modify loads by:

• Moving line load ends

• Moving uniform load corners

• Changing the shape of openings in loads

• Adding corners to uniform loads

Handles Tekla Structures indicates the load reference points (the ends and corners of line, area, and uniform loads) using handles. When you select a load, the handles are magenta.

You can use these handles to move load ends and corners:

1. Select the load to display its handles.

2. Click the handle you want to move. Tekla Structures highlights the handle.

3. Move the handle(s) like any other object. See Moving an object. If you have Drag and drop on, just drag the handle to a new position. See Moving an object using drag-and-drop.

To add corners to uniform loads, use the Modify Polygon Shape command. See Modifying the shape of a polygon.

Scaling loads in model views

You can have Tekla Structures scale loads when you are modeling. This ensures that loads are not too small to see, or so large that they hide the structure.

To scale loads in model views, click Tools > Options > Options... > Load modeling and go to the Arrow length tab:


Example You define that point loads with magnitude of 1 kN or less are 250 mm high in the model, and point loads with magnitude of 10 kN or more are 2500 mm high. Tekla Structures linearly scales all point loads that have a magnitudes between 1 kN and 10 kN between 250 mm and 2500 mm.

Defining varying wind loads

The Create Wind Load (p. 63) command allows you to define which zones have concentrated wind load. Each zone is the height of the wall. Define the width of the zone using either dimensions or proportions. You can define up to five zones for each wall.

In the example below, the loads in the global x direction are multiplied by 3 at both corners of wall 1.


Loads

The Wind load generator (28) dialog box contains one tab for each wind direction.

2.6 Load referenceThis section consists of the reference pages for the load commands.

To create loads, use the icons on the Loads and Analysis toolbar or select a command from the Analysis > Loads menu. The following table lists the commands for creating loads and gives a short description of each one.

Load Groups...

Synopsis This command displays the Load Groups dialog box that you can use to manage load groups.

Command Icon Description

Load Groups... (p. 56) Displays the Load Groups dialog box.

Create Point Load (p. 58)

Creates a point load at a picked position.

Create Line Load (p. 59)

Creates a line load between two picked points.

Create Area Load (p. 60)

Creates an area load using three picked points.

Create Uniform Load (p. 61)

Creates a uniformly-distributed polygonal area load using at least three picked points.

Create Wind Load (p. 63)

Creates wind loads on a structure.

Create Temperature Load (p. 62)

Defines a temperature change in a part, or a temperature difference between two part surfaces.


Description Tekla Structures lists all the existing load groups in the Load Groups dialog box. Use the dialog box to view, define, modify, and delete load groups.

Usage Click Analysis > Loads > Load Groups....

To define a new load group:

1. Click Add.

2. Select the default load group from the list.

3. Click the load group name to modify it.

4. Click the load group type and select a type from the list box.

5. Click the load group direction to modify it.

6. To indicate compatibility with existing load groups:

• In the Compatible column, enter the number you have used for the load groups that are compatible with this load group.

• In the Incompatible column, enter the number you have used for the load groups that are incompatible with this load group.

7. Click OK to close the dialog box.

To modify an existing load group:

1. Select the load group from the list.

2. Change the name, direction, group type, or compatibility indicators.

3. Click OK to close the dialog box.

To delete a load group:

1. Select the load group from the list.

2. Click Delete.

3. Click OK in the warning dialog box. This also deletes the loads in the load group.

Column Description More information

Current The @ symbol identifies the current load group. To change the current load group, select a load group and click the Set current button.

Load group properties (p. 43)

Name Unique name of the load group.

Type Load group type, based on the action that causes the loads in the group.

Direction Direction of the action that causes the loads in the load group.

Compatible A number that identifies all the load groups that are compatible with each other.


Incompatible A number that identifies all the load groups that are incompatible with each other.

Color The color that Tekla Structures uses to show the loads in the group.

Load group properties (p. 43)


Loads

To find out which loads belong to a load group:

1. Open the Load Groups dialog box.

2. Select a load group in the dialog box.

3. Click the Loads by load groups button. Tekla Structures highlights the loads in the model.

To find out which load group a load belongs to:

1. Open the Load Groups dialog box.

2. Select a load in the model.

3. Click the Load groups by loads button. Tekla Structures highlights the load group in the dialog box.

To move a load to a different load group:

1. Select the load in the model.

2. Select a load group in the Load Groups dialog box.

3. Click the Change load group button.

To export load groups:

1. Select the load groups to export in the Load Groups dialog box.

2. Right-click and select Export... from the pop-up menu.

3. In the Export Load Groups dialog box, browse for a folder and enter a name for the load group file.

4. Click OK.

To import load groups:

1. In the Load Groups dialog box, right-click on the load group list and select Import... from the pop-up menu.

2. In the Import Load Groups dialog box, browse for the load group files (.lgr) to import.

3. Click OK.

See also Working with load groups (p. 44)

Grouping loads (p. 42)

Create Point Load

Synopsis This command creates a point load at a position you pick.

Preconditions Shift the work plane to create loads perpendicular to sloped parts.

When you delete a load group, Tekla Structures also deletes all the loads in the load group.

If you try to delete the only load group, Tekla Structures will warn you. At least one load group must exist.

You can include several load groups in one load group file.


Description Tekla Structures creates the point load using the properties in the Point Load Properties dialog box. The filename extension of a point load properties file is lm1.

Usage 1. Double-click the Create point load icon.

2. Enter or modify the load properties.

3. Click Apply or OK to save the properties.

4. If you have selected the Attach to member option, select the part to attach the load to.

5. Pick the position of the load.

See also Points

Creating a point

Using commands

Create Line Load

Synopsis This command creates a line load between two picked points.


Description Tekla Structures creates the line load using the properties in the Line Load Properties dialog box. The filename extension of a line load properties file is lm2.

Field Description More information

Load group name

The load group to which the load belongs.


Load Groups... (p. 56)

Magnitude tab Load magnitudes in the x, y, and z directions of the work plane.


Load attachment

Indicates if the load is attached to a part.


Load-bearing parts

Parts to which the load is applied, or not applied, on the basis of part names or selection filters.


Bounding box of the load

Dimensions of the bounding box in the x, y, and z directions.

Load panel tab Properties used in the load panel load distribution method.

Modifying load distribution (p. 52)


Load group name




Load form Defines how the load magnitude varies along the loaded length.

Load forms (p. 48)


Loads

Usage 1. Double-click the Create line load icon.




5. Pick the starting point.

6. Pick the end point.

See also Points

Creating a point

Using commands

Create Area Load

Synopsis This command creates an area load using three picked points.


Description Area loads affect triangular or quadrangular areas. If you select the triangular load form, the points you pick define the loaded area. To create a quadrangular load form, pick three points and Tekla Structures automatically determines the fourth corner point.

Tekla Structures creates the area load using the properties in the Area Load Properties dialog box. The filename extension of an area load properties file is lm3.



Load attachment



Load-bearing parts





Distances Offsets from the load end points, used to shorten or lengthen the loaded length.






Load group name




Load form Defines the shape of the loaded area.

Load forms (p. 48)


Usage 1. Double-click the Create area load icon.




5. Pick three corner points.

See also Points

Creating a point

Using commands

Create Uniform Load

Synopsis This command creates a uniformly-distributed, polygonal area load using at least three picked points.


Description Uniform load is an area load distributed uniformly on a polygonal area. The bounding polygon is defined by at least three corner points you pick. Uniform loads can have openings.

Tekla Structures creates a uniform load using the properties in the Uniform Load Properties dialog box. The filename extension of a uniform load properties file is lm4.



Load attachment



Load-bearing parts





Distances Offset used to enlarge or reduce the loaded area.





Tekla Structures automatically takes openings in plates, slabs, and panels into account. To omit openings when analyzing plates, use the user-defined attribute Minimum hole size. For more about user-defined attributes, see Fine-tuning analysis models (p. 31).


Loads

Usage 1. Double-click the Create uniform load icon.




5. Pick three corner points.

6. (Pick the other corner points.)

7. Pick the first point again and click the middle mouse button to finish picking.

See also Points

Creating a point

Using commands

Create Temperature Load

Synopsis This command defines a temperature change in a part, or a temperature difference between two part surfaces.

Description Tekla Structures creates the temperature load using the properties in the Temperature Load Properties dialog box. The filename extension of a temperature load properties file is lm6.


Load group name






Load attachment



Load-bearing parts





Distances Offset used to enlarge or reduce the loaded area.




Tekla Structures automatically takes openings in plates, slabs, and panels into account. To omit openings when analyzing plates, use the user-defined attribute Minimum hole size. For more about user-defined attributes, see Fine-tuning analysis models (p. 31).


Usage 1. Double-click the Create temperature load icon.




5. Pick the starting point.

6. Pick the end point.

See also Points

Creating a point

Using commands

Create Wind Load

Synopsis This modeling tool creates wind loads on a structure.


Load group name




Magnitude tab Temperature change in the part. Temperature loads and strain (p. 49)Difference in temperature

between the left and right sides of the part.

Difference in temperature between the top and bottom surfaces of the part.

Axial strain of the part.

A positive value indicates elongation, a negative value indicates shrinkage.

Load attachment



Load-bearing parts





To apply temperature load to an entire structure, enter the load in the Temperature change for axial elongation field and adjust the bounding box to surround all the beams and columns in the structure.


Loads

Preconditions

Description Tekla Structures creates wind loads using the properties in the Wind load generator (28) dialog box. The properties are:

Tekla Structures automatically includes wind loads in load combinations. To also include wind loads from the opposite direction, select the Generate wind also in opposite direction checkbox when creating load combinations.

Wind load generator (28) automatically takes openings in plates, slabs, and panels into account.

Usage 1. Double-click the Create wind load icon.

2. Enter or modify the properties.


4. Pick points to indicate the shape of the building on the bottom level.

5. Click the middle mouse button to finish.


Wind load direction

The options are:

• Global X

• Global -X

• Global Y

• Global -Y

• Global X, -X, Y, -Y (for all directions)

Nominal wind pressure

Top level The highest level of the wind loads.

Bottom level The lowest level of the wind loads.

Ground level The level of the ground around the building.

Part names Parts to which the load is applied, or not applied.


Front The external exposure factors for the windward, leeward, and side walls.

A positive value indicates pressure, a negative value indicates suction.

Left side

Back

Right side

Internal The internal exposure factor.

Z profile tab The distribution of wind load along the height of the building, in terms of pressure factors. Starts from the ground level.

Global X, Global Y, Global -X, Global -Y tabs

Zones for concentrated corner loads for each wall. You can define up to five zones for each wall.

Defining varying wind loads (p. 55)


See also Automatically including loads in combinations (p. 88)

Wind load generator (28) creates area loads using the load panel distribution method. For more information, see Modifying load distribution (p. 52).


Loads

TEKLA STRUCTURES 15 67Analysis and Design

3 Analysis and Design

Introduction This chapter explains how to define analysis model geometry in Tekla Structures. It also includes a general description of analysis and design model properties and an overview of analysis commands. You will also learn how to create load combinations.

Audience This chapter is for engineers who run structural analysis on concrete and steel structures.

Assumed background

We assume that you have read the Chapter 1, Getting Started with Analysis (p. 11), first and defined the support conditions for parts.


• Analysis model geometry (p. 67)

• Analysis model properties (p. 74)

• Load combination (p. 83)

• Working with analysis and design models (p. 89)

• Analysis and design reference (p. 94)

3.1 Analysis model geometryIntroduction This section explains how to define analysis model geometry.

Analysis model geometry is a representation of analysis settings applied to a physical model. It indicates, for example, the locations of member axes. The analysis model geometry is a means to ensure that each analysis model passed on to the analysis application is accurate.

The analysis model geometry includes analysis parts, part nodes, connection nodes, and links between nodes.

You can show analysis parts in Tekla Structures model views. See View Analysis Parts (p. 102).

Defining analysis model geometry

You can define analysis model geometry by using:

• Analysis model geometry settings for the entire physical model and all its analysis models

• Analysis model geometry rules for specific parts in the physical model

• Analysis properties of individual parts and connections


Analysis and Design

• Analysis model properties that control the locations of member axes and nodes

Modifying the analysis model geometry does not affect the physical model.

Geometry settings

Analysis model geometry settings define how Tekla Structures creates analysis models of the physical model by default.

You can define limits for when to use rigid links (Rigid link limit) and when to merge nodes on a part (Merge distance on beams).

To access the analysis model geometry settings, click Analysis > Geometry Settings..., or

.

You can also use analysis model geometry rules to control the analysis model geometry. Geometry rules specify what Tekla Structures does for specific parts in specific conditions to force members to meet in the analysis model, or to prevent them from connecting. For example, you may want Tekla Structures to merge nodes in certain conditions, and in other conditions you may prefer rigid links.

Analysis geometry rules are based on selection filters. For example, you can define that parts matching the columns filter always keep their member axis locations.

See also Creating rules to define analysis model geometry (p. 68)

Modifying analysis model geometry (p. 70)

Connecting or disconnecting parts in analysis (p. 70)

Defining analysis connections of parts (p. 71)

Analysis part properties (p. 72)

Analysis model properties (p. 74)

Creating rules to define analysis model geometry

You can control analysis model geometry with rules created on the basis of selection filters. You can create rules to define how Tekla Structures handles individual parts when it creates analysis models, and how parts are connected with each other in the analysis.

Preconditions Create the physical parts and define their individual analysis properties if needed.

Usage To create analysis model geometry rules:

1. Click Analysis > Geometry Settings..., or .

2. In the Analysis Geometry Settings dialog box, click Analysis geometry rules....

The Analysis Geometry Rules dialog box is displayed.

On the Part properties tab:

1. Click Add to add rules to define individual analysis part properties.

2. In the Selection filter column, select a filter for each rule.

The properties defined by a rule will be applied to the parts matching the filter.

3. In the Keep axis position always column:

• Select Yes to fix the member axis locations of the filtered parts.

4. In the Merge distance on part column, define the distance within which the nodes on the filtered parts are merged to connection nodes.


5. In the Exact connectivity column:

• Select Yes to connect parts only if their member axes intersect.

On the Part connectivity tab:

1. Click Add to add rules to define how two groups of parts are connected with each other in the analysis.

2. In the Selection filter 1 column, select a filter to define the first part group.

3. In the Selection filter 2 column, select a filter to define the second part group.

4. In the Status column:

• Select Disabled to prevent connections between the part groups.

5. In the Linkage column, select an option:

On both tabs:

• Click Move up or Move down to change the order of rules.

• Click Selection filter... to create a new selection filter that suits your needs.

• Click Test selected part or Test selected parts to see how rules affect the parts selected in the model.

• Click Remove to delete the selected rules.

To save the settings:

1. To save the analysis geometry rules for later use, enter a name in the field next to the Save as button, and then click Save as.

The filename extension of an analysis geometry rules file is adrules.

2. Click OK to save the rules and close the Analysis Geometry Rules dialog box.

Option Description

(blank) Merges nodes or creates a rigid link according to the rigid link limit defined in the Analysis Geometry Settings dialog box.

Merge Always merges nodes when parts matching the selection filter 1 connect with parts matching the selection filter 2.

Rigid link Creates a rigid link when parts matching the selection filter 1 connect with parts matching the selection filter 2.

Rigid link, moment release at node 1

Creates a rigid link and a moment release at the nodes of parts matching the selection filter 1.

Rigid link, moment release at node 2

Creates a rigid link and a moment release at the nodes of parts matching the selection filter 2.

Rigid link, moment release at both nodes

Creates a rigid link and moment releases at the nodes of parts matching the selection filters 1 and 2.

The order of the rules is important.

On the Part connectivity tab, the last rule applicable to a part is used.

On the Part properties tab, the last rule applicable to a pair of parts is used.


Analysis and Design

3. Click OK to save the rules with geometry settings and to close the Analysis Geometry Settings dialog box.

See also Filtering objects

Analysis model geometry (p. 67)

Modifying analysis model geometry (p. 70)

Modifying analysis model geometry

In addition to changing the analysis model geometry settings, you can graphically modify the geometry by moving analysis part handles, or you can use the commands in Analysis > Edit Geometry.

Preconditions Switch View Analysis Parts on to show the analysis parts.

A check mark next to View Analysis Parts on the Analysis menu indicates that the analysis parts are already visible.

Usage To modify an analysis part by using its handles:

1. Select the analysis part to show the handles.

The analysis part handles are white.

2. Select the handle you want to move.

3. If you have Drag and Drop (shortcut D) active, just drag the handle to a new location, or use the Move commands to move handles.

See also Connecting or disconnecting parts in analysis (p. 70)

Defining analysis connections of parts (p. 71)

Reset Geometry for Selected Parts (p. 102)

Connecting or disconnecting parts in analysis

You can connect and disconnect individual parts in the analysis.

Usage To connect parts:

1. Select the parts to connect.

2. Click Analysis > Edit Geometry > Connect Parts, or .

Use the appropriate snap switches to snap to the correct locations, for example, Snap to perpendicular points. See Snap switches.


To disconnect parts:

1. Select the parts to disconnect.

2. Click Analysis > Edit Geometry > Disconnect Parts, or .

See also Modifying analysis model geometry (p. 70)


Defining analysis connections of parts

Use the Analysis Member Connectivity dialog box, in addition to the analysis geometry settings, to define the analysis connections of a part to other parts.

Description You can:

• Force parts to connect if they do not connect according to the geometry settings.

• Prevent parts from connecting if they connect according to the geometry settings.

• Ignore the geometry settings and define all connections manually.

• View the analysis connections that you have modified using the Connect Parts and Disconnect Parts commands.

Usage To view or modify the analysis connections of a part:

1. Click Analysis > Edit Geometry > Edit Part Connectivity..., or .

2. Select the part.

To use the analysis model geometry settings but override them for the part:

1. In the Connectivity mode list box, select Automatic.

2. Select the parts to connect to and click Add selected parts next to the Additional forced connectivity list.

3. Select the parts to disconnect from and click Add selected parts next to the Prevented connectivity list.

4. Click OK.

To ignore the analysis model settings for the part and define all analysis connections manually:

1. In the Connectivity mode list box, select Manual.

2. Select the parts to connect to and click Add selected parts.

3. Click OK.


Connecting or disconnecting parts in analysis (p. 70)


You can view the modified analysis connections of a part in the Analysis Member Connectivity dialog box. See Defining analysis connections of parts (p. 71).


Analysis and Design

Analysis part properties

An analysis part is a representation of analysis properties applied to a physical part. It indicates, for example, the location of the member axis.

You can show analysis parts in Tekla Structures model views. See View Analysis Parts (p. 102).

You can use the properties of analysis parts to fine-tune analysis model geometry for specific parts, for example, for built-up sections.

To access the properties of an analysis part:

1. Select the part.

2. Click Analysis > Properties > Analysis Part....

The Analysis Part Properties dialog box is displayed.

The table below describes the analysis part properties. They correspond to the user-defined attributes (UDA) of parts used in the previous versions of Tekla Structures.

Property DescriptionCorresponding UDA

Built-up section mode

Indicates the role of the part in a built-up section that consists of a main part and one or more sub-parts. In the analysis, merges the sub-parts to the main part.

The options are:

• Automatic

• Not part of built-up section: Disconnects the part from a built-up section.

• Main part of built-up section: Always use to define the main part of a built-up section.

• Sub-part of built-up section

• Beam sub-part of built-up section: Defines that the main part is a beam.

• Column sub-part of built-up section: Defines that the main part is a column.

Exact connectivity Select Yes to connect parts only if their member axes intersect.

Merge distance on part

Merges nodes within the distance specified into a single node.

Node merge distance

Keep axis position always

Select Yes to fix the location of member axis so that Tekla Structures does not shift the axis when it makes members meet in the analysis model.

Keep axis

Fixed level (z) of member

Sets the same z coordinate for all nodes. Member level (z)


Replacement profile name

Select a profile from the profile catalog.

You can use different analysis profiles at the start and end of parts if the analysis application you use supports it.

To use different profiles at part ends, enter two profiles separated by a pipe character, for example:

HEA120|HEA140

Profile

Longitudinal offset mode

Defines whether the longitudinal analysis offsets Dx of the physical part are used (part properties dialog box, Analysis tab).

See also Analysis member offsets (p. 18).

The options are:

• Offsets are not considered

• Only extensions are considered

• Offsets are always considered

Consider longitudinal model offsets

Curved beam mode Defines whether a beam is analyzed as a curved beam or as straight segments. Select either:

• Use curved member

• Split into straight segments

Use the variable XS_AD_CURVED_BEAM_SPLIT_ACCURACY_MM in Tools > Options > Advanced Options... > Analysis & Design to define how closely straight segments follow the curved beam.

Curved beam by straight segments

Design group Defines which design group the part belongs to. Used in optimization.

Design group (optimization)

No. of split nodes Use to create additional nodes or analyze a beam as straight segments, for example, a curved beam.

Enter the number of nodes.


No. of split nodes

Split distances To define additional nodes in the member, enter distances from the part starting point to the node.

Enter distances, separated by spaces, for example:

1000 1500 3000


Split distances



Analysis and Design

3.2 Analysis model propertiesThis section explains the properties that Tekla Structures uses to create analysis members and analyze them. These properties apply to all members in an analysis model.

Rigid link Enables or disables rigid links at the start, mid, and end points of parts.

Use with the Force to centric connection option in the Analysis Model Properties dialog box to specify which parts to use rigid links.

See also Using rigid links (p. 35).

Rigid link


Connects the part using pinned rigid links to the parts you specify.


Simple plate model Select Yes to create a simpler analysis model of plates, where cuts and openings are not considered.

Simple plate

Smallest hole size to consider

Use to ignore small openings in plates in the analysis.

Enter the size of the bounding box around the opening.

Minimum hole size (to consider)

Supported Use to define supports for plates and beams.

You can create supports for the bottom edge of a wall, for all edge nodes of a slab, or for all nodes of a beam. For walls the bottom edge can be inclined.

The options are:

• Simply: only translations are fixed

• Fully: both translations and rotations are fixed

Supported

Beam offsets tab Use to move analysis part ends to force members to meet in the analysis model.

You can also move analysis part ends using handles. See Modifying analysis model geometry (p. 70).

Node offsets



Tekla Structures also takes into account the individual analysis properties defined in the parts’ properties. See Determining member properties (p. 14).

Defining analysis model properties

To set the properties for a new analysis model:

1. Click Analysis > Analysis & Design Models....

2. Click New....

To view or modify the properties of an existing analysis model:


2. Select the model.

3. Click Properties....


Tekla Structures links with a number of analysis applications and also supports import and export with them in several formats. The analysis application you use to run structural analysis uses data from the analysis model to generate analysis results.

Model name Each analysis model must have a unique name, which you can define. For example, you could use a name that describes the portion of the physical model you want to analyze.

Topics Objects in an analysis model (p. 76)

Member axis (p. 77)

Member end connectivity (p. 78)

Defining nodes (p. 78)

Model merging with analysis applications (p. 79)


Seismic analysis (p. 80)

Modal analysis (p. 81)

Design codes and methods (p. 82)

Contents of STAAD.Pro results files and reports (p. 82)


Analysis and Design

Objects in an analysis model

You can define which objects to include in an analysis model. For example, you can create analysis models of:

• The entire physical and load models

• A particular sub structure under a specific loading

• A single part

Creation method To define which objects to include in an analysis model, open the Analysis Model Properties dialog box. On the Analysis model tab, select an option from the Creation method list box. The options are:

Option Description

Full model Includes all main parts and loads, except for parts whose analysis type is set to Ignore on the Analysis tab of part dialog box. Tekla Structures automatically adds physical objects to the analysis model when they are created.

By work area Includes all the main parts and loads that are inside or partly inside the work area when you create the analysis model.

By selected parts Only includes selected parts.

By selected parts and loads

Only includes selected parts and loads, and parts created by components. To later add or remove parts and loads, use the following buttons in the Analysis & Design Models dialog box:

• Add selected objects

• Remove selected objects

Floor model by selected parts and loads

Only includes selected columns, slabs, floor beams, and loads. Tekla Structures replaces columns in the physical model with supports.

Tekla Structures ignores some objects in the analysis. See A closer look at the analysis model (p. 37).

Even if you select Full model, Tekla Structures does not include parts created by most components in the analysis model. The following components set the analysis properties of the parts they create, so these parts are included in the analysis model:

• Truss (S78)

• Shed (S75)

• Building (S58) and (S91)

• Slab generation (61) and (62)


See also Analysis model filter (p. 77)

Analysis model filterTo use the analysis model filter to select objects to include in an analysis model, select a filter from the Filter list box on the Analysis model tab in the Analysis Model Properties dialog box. The analysis model filter works in similar way to the selection filter (see Filtering objects using a selection filter), but Tekla Structures saves the settings with the analysis model properties. So you can go back and check the criteria you used to select objects.

Tekla Structures automatically adds new objects you create in the physical model to the analysis model if they fulfill the criteria in the analysis model filter.

See also To add individual objects to an analysis model, or to remove them, see Adding or removing analysis objects (p. 90).

To check which objects are included in an analysis model, see Checking objects contained in an analysis model (p. 90).


Working with analysis and design models (p. 89)

Member axis

The locations of the member axes of parts define where the analysis members actually meet, and their length in the analysis model. They also affect where Tekla Structures creates nodes.

To define member axis locations for all members in an analysis model, open the Analysis Model Properties dialog box. On the Analysis model tab, select an option from the Member axis location list box. The options are:

When you create an analysis model using the Full model option, the number of objects in the Analysis & Design Models dialog box changes only when you update the analysis model.

Use the analysis model filter to filter out non-structural parts, such as railings, from the analysis model.

Option Description

Neutral axis The neutral axis is the member axis for all parts. The location of the member axis changes if the profile of the part changes.

Reference axis The part reference line is the member axis for all parts. See also Part position.


Analysis and Design

See also To visually check the analysis model before running the analysis, see Showing analysis models and support conditions in model views (p. 90).


Member end connectivity

You can choose to define the support conditions of individual analysis members according to the part’s properties, or the support conditions of connections between parts. See Support conditions (p. 25).

To have Tekla Structures use the support conditions of connections:

1. For each connection or detail, open the properties dialog box. On the Analysis tab, select Yes in the Use analysis restraints list box. See Analysis properties of components (p. 22).

2. Open the Analysis Model Properties dialog box for an analysis model. On the Analysis model tab, select Yes in the Member end release method by connection list box.

Select No in the Member end release method by connection list box to have Tekla Structures use the support conditions of individual parts.

See also Analysis model properties (p. 74)

Showing analysis models and support conditions in model views (p. 90)

Defining nodes

If physical parts collide, but their member axes do not intersect, you can have Tekla Structures create common nodes for them in the analysis model by using the Extended clash check option in the Analysis Model Properties dialog box. In order to force the members to meet in the analysis model, Tekla Structures may need to use the methods described in A closer look at the analysis model (p. 37).

Node definition method

If Tekla Structures cannot merge nodes because they are outside the merge distance (XS_AD_NODE_COLLISION_CHECK_DISTANCE), you can define how to connect members. Open the Analysis Model Properties dialog box. On the Analysis model tab, select one of the following options in the Node definition list box:

Reference axis (eccentricity by neutral axis)

The part reference line is the member axis for all parts. The location of the neutral axis defines axis eccentricity.

Model default The member axis of each part is defined individually according to the part’s properties. See Member axis location (p. 17).

If you select the Neutral axis option, Tekla Structures takes the part location and end offsets into account when it creates nodes. See End offsets. If you select either of the Reference axis options, Tekla Structures creates nodes at part reference points.

Option Description


Rigid links Rigid links have the following properties in the analysis model:

• Profile = PL300.0*300.0

• Material = RigidlinkMaterial

• Density = 0.0

• Modulus of elasticity = 100*109 N/m2

• Poisson’s ratio = 0.30

• Thermal dilatation coefficient = 0.0 1/K

See also To visually check the analysis model before running the analysis, see Showing analysis models and support conditions in model views (p. 90).


Model merging with analysis applicationsUpdating changes

You can merge analysis models with some analysis applications, which means that existing models in analysis applications update when changes occur in Tekla Structures analysis models.

To use model merging, select Enabled in the Model merging with analysis applications list box in the Analysis Model Properties dialog box.

In analysis applications that support model merging, you can, for example, add special loads to analysis models, in addition to the loads created in Tekla Structures, then make changes in Tekla Structures, and still keep the model in the analysis application up to date.

Option Image Description

Use rigid links Creates a node at each member’s axis and connects the members using a rigid link between the nodes.

Force to centric connection

Creates a single node for the members and forces them into a centric connection by extending the member axes.

With both node definition methods you can override the setting at specific places. For more information, see Using rigid links (p. 35).


Analysis and Design

Keeping node and member numbers

With all analysis applications, model merging helps in keeping the node and member numbers unchanged when changes occur in the analysis model.

• Node numbers are kept if the node coordinates stay the same.

• Member numbers are kept if the start and end node numbers stay the same.

• Old numbers are not re-used.

Resetting models To renumber nodes and members, or to remove a Tekla Structures analysis model from an analysis application, click the Reset button next the Model merging with analysis applications list box in the Analysis Model Properties dialog box.

Analysis method

To define the analysis method for the model, open the Analysis Model Properties dialog box. On the Analysis tab, select an option from the Analysis method list box. The options are:

If you select P-delta, Tekla Structures takes into account the additional stresses induced by the deflections of the structure. This leads to the iteration of deflection.

Iteration The accuracy of the second order analysis depends on the number of iterations; the longer the iteration goes on, the more accurate the analysis. Increasing the number of iterations also increases processing time and analysis model size. To limit the number of iterations in second order analysis, enter a value in the Maximum number of iterations field. You can also set the accuracy, which is the relative tolerance used to control the iteration of deflection.

Iteration stops when the analysis reaches the accuracy or the maximum number of iterations you define on the Analysis tab.


Seismic analysisType To define which building code to use to generate seismic loads, use the Seismic tab in the

Analysis Model Properties dialog box. You can create lateral seismic loads in the x and y directions according to several codes using a static equivalent approach (z is the direction of the gravity loads). Select one of the following options in the Type list box:

Option Description

1st order Linear analysis method.

P-delta A simplified second order analysis method. This method gives accurate results when deflections are small.

Non-linear Non-linear analysis method

Option Description

None Seismic analysis not run.

UBC 1997 Uniform Building Code 1997

UBC 1994 Uniform Building Code 1994

IBC 2000 International Building Code 2000

IS 1893-2002 Indian Standard. Criteria for Earthquake Resistant Design of Structures

IBC 2003 International Building Code 2003


Properties Depending on the code you select, you can define some or all of the following:

• Whether to calculate the accidental torsion

• Seismic zone coefficient (Zone)

• Importance factor

• Numerical coefficients Rw for the lateral loads in x and y directions

• Soil profile type

• Soil factor

• Site class

• SDS, SD1, S1

• Near source factors NA and NV

• CT value to calculate time period

• Periods of structure (in seconds) in the x and y directions

• Response reduction factor

• Type of structure

• Damping ratio

• Depth of foundation below ground level

Seismic loads Use the Seismic masses tab in the Analysis Model Properties dialog box to define the load groups and load group factors to include in the seismic analysis.

To include the self-weight of parts in the seismic analysis, select the Include self-weight as seismic mass checkbox.

To use the same load groups from the modal analysis in the seismic analysis, click the Copy modal analysis masses button.

To move load groups between the Selected load groups and Not selected load groups lists, select a load group and use the arrow buttons between the lists.


Modal analysis

To use modal analysis properties (resonant frequency and the associated pattern of structural deformation called mode shapes) instead of static load combinations:

1. Open the Analysis Model Properties dialog box. On the Analysis model tab, select the Modal analysis model checkbox. This forces Tekla Structures to ignore static load combinations.

2. On the Modal analysis tab, define the following properties:

AIJ Japanese code

Response spectrum Response spectrum specification

Option Description


Count of modes The number of natural mode shapes in the structure.

Max frequency The maximum natural resonant frequency of the structure.


Analysis and Design

3. To move load groups between the Selected load groups and Not selected load groups lists, select a load group and use the arrow buttons between the lists.

4. For each load group, enter a load factor and set the mass direction, the options are:

• XYZ to include the load in all three directions.

• Model default to include the load only in the direction of the load.


Design codes and methods

Use the Design tabs in the Analysis Model Properties dialog box to define the code and method to use in structural design. The design options available vary depending on the material.

The design code options available vary depending on the analysis application you use.

The design method options of different materials are:

Design propertiesWhen you select a design code and method for a material, Tekla Structures lists the design properties in the lower part of the Design tab in the Analysis Model Properties dialog box. Click on an entry in the Value column to change the value of a particular property.

To change the design properties of specific parts, use the Design tab in the appropriate part properties dialog box. See Design information (p. 27).


Contents of STAAD.Pro results files and reports

If STAAD.Pro is the analysis application you use, you can define the contents of the analysis results files and reports in the Analysis Model Properties dialog box in Tekla Structures.

Use the Output tab to define the contents of the analysis results files.

Include self-weight Select checkboxes to indicate the directions for which Tekla Structures includes the self-weight of parts in the modal analysis.

Copy seismic masses

Select to include the same load groups in the modal analysis as in the seismic analysis.


Option Description Material

None Tekla Structures only runs a structural analysis and creates data on stresses, forces, and displacements.

Steel

Concrete

Timber

Check design Tekla Structures checks whether the structures fulfill the criteria in the design code (i.e. whether cross sections are adequate).

Steel

Timber

Calculate required area

Tekla Structures defines the required area of reinforcement.

Concrete


Use the Job tab to define the contents of the STAAD.Pro reports. The properties you can include in reports are:

See also Running analysis (p. 93)

3.3 Load combinationIntroduction Load combination is a process in which some simultaneously acting load groups are multiplied

by their partial safety factors and combined with each other according to specific rules.

Load combination rules are specific to a design process and are defined in building codes. One of the most typical design processes is the limit state design.

The result of the load combination process is a load combination.

You can have Tekla Structures automatically create load combinations, or you can create and modify them manually.

Topics Load combination properties (p. 83)

Load combination factors (p. 84)

Load combination types (p. 84)

Creating load combinations (p. 86)

Automatic load combination (p. 87)

Automatically including loads in combinations (p. 88)

Manual load combination (p. 88)

Load combination properties

Load combination properties define how Tekla Structures combines loads. The following properties control the load combination process:

• Load modeling code (p. 39)

• Load combination factors (p. 84)

• Load combination types (p. 84)

Property Field in STAAD.Pro reports

Name Job title, Client, Job Number, Part, and Reference fields in the report header (displayed on each page).

Client

Number

Part

Reference

Comment Comments field in Job information item in the report.

Engineer Engineer and Checker names appear in the report header and in the Job information field.Checker

Approved Acceptor name, appears in the Job information field.


Analysis and Design

• Load group compatibility (p. 43)

Name and ID Each load combination must have a unique name. Use names that describe the load situation.

Each load combination has an ID. This is an incremental number, based on order in which load combinations are created in the analysis model.

See also Creating load combinations (p. 86)

Load combination factors

You can use values for load combination factors that are building-code specific or user-defined. To use building-code specific factors, click Tools > Options > Options... > Load modeling. On the Current code tab, select an option from the Load modeling code list box. See Load modeling code (p. 39).

If you change any values on the code-specific tabs, save the properties using a new name. To do this, enter a name in the field next to the Save as button and click the Save as button.

Partial safety factors

The partial safety factors needed in the limit state design appear on the code-specific tabs. They are:

• Unfavorable partial safety factor in the ultimate limit state (γsup)

• Favorable partial safety factor in the ultimate limit state (γinf)

• Unfavorable partial safety factor in the serviceability limit state (γsup)

• Favorable partial safety factor in the serviceability limit state (γinf)

Reduction factors Depending on the codes you use, you may need to use other combination factors. For example, the Eurocode contains three reduction factors (ψ0, ψ1, ψ2). Reduction factors exclude the

impractical effects of simultaneous loads.


Load combination types

You can perform several types of load combination, which vary according to the building code you use. The options are:

You should not need to change these settings during the project. If you have to, you will also need to change the load group types and check load combinations.

Combination type DescriptionApplies to

Load groups (LG) Each load group forms a load combination. All partial safety factors equal 1.00.

All codes

Ultimate limit state (ULS)

Combines load groups that occur persistently and transiently. Uses the partial safety factors of the ultimate limit state when combining loads.

Eurocode, British, AISC


Serviceability limit state – Rare (SLS RC)

Combines load groups that occur quasi-permanently and rarely. Uses the partial safety factors of the serviceability limit state when combining loads.

Eurocode

Serviceability limit state – Quasi-permanent (SLS QP)

Combines load groups that occur quasi-permanently. Uses the partial safety factors of the serviceability limit state when combining loads.

Eurocode

Serviceability limit state (SLS)

Combines load groups that occur quasi-permanently. Uses the partial safety factors of the serviceability limit state when combining loads.

AISC

Normal loads Combines load groups and uses factors according to the French codes CM66 or BAEL91.

CM66, BAEL91

Extreme loads CM66

Displacement loads CM66

Accidental loads CM66

Ultimate loads BAEL91

Ultimate accidental loads

BAEL91

Loads for public structures

Combines load groups according to the US IBC code (International Building Code)

IBC (US)

Loads for public structures with drifted snow

IBC (US)

Loads for non public structures

IBC (US)

Loads for non public structures with drifted snow

IBC (US)



Analysis and Design

Use the Load Combination Generation dialog box to define the load combination type.



Automatically including loads in combinations (p. 88)

Creating load combinations

To create load combinations:


2. In the Analysis & Design Models dialog box, select an analysis model and click Load combinations... to open the Load Combinations dialog box. This lists the existing load combinations, together with their ID, name, type, and the load groups they contain.

Loads for public non concrete and masonry structures

Combines load groups according to the US UBC code (Uniform Building Code)

UBC (US)

Loads for public non concrete and masonry structures with drifted snow

UBC (US)

Loads for non concrete and masonry structures

UBC (US)

Loads for non concrete and masonry structures with drifted snow

UBC (US)

Loads for public concrete and masonry structures

UBC (US)

Loads for public concrete and masonry structures with drifted snow

UBC (US)

Loads for concrete and masonry structures

UBC (US)

Loads for concrete and masonry structures with drifted snow

UBC (US)

ACI Table 1 - ACI Table 8

Combines load groups according to the ACI code (American Concrete Institution’s publication 318)

ACI



Use the buttons in the Load Combinations dialog box to carry out various tasks. The buttons are:

Automatic load combination

To automatically create load combinations:

1. In the Load Combinations dialog box, click Generate... to open the Load Combination Generation dialog box.

Button Description

New... Displays the Load Combination Coefficients dialog box, where you manually create load combinations. See Manual load combination (p. 88).

Generate... Automatically generates load combinations based on the code and factors in Tools > Options > Options... > Load modeling. See Automatic load combination (p. 87).

Remove Deletes the selected load combination.

Remove all Deletes all load combinations.

Use the Save as and Load buttons to copy load combinations between analysis models.


Analysis and Design

2. In the upper part of the dialog box, select the checkboxes against the combinations you want to create. See Load combination types (p. 84).

3. To automatically include the self-weight of parts or wind loads from the opposite direction, select the appropriate checkboxes in the lower part of the dialog box. See Automatically including loads in combinations (p. 88).

4. Click Apply or OK.

Tekla Structures creates the load combinations for different load groups and limit states according to the load modeling code you select, and uses the combination factors defined in Tools > Options > Options... > Load modeling.

See also Creating load combinations (p. 86) and Manual load combination (p. 88).

Automatically including loads in combinations

You can automatically include various loads in load combinations. To do this, select the appropriate checkboxes in the Load Combination Generation dialog box. The options are:



Load combination types (p. 84)

Manual load combination

To create load combinations manually:

Checkbox Description Applies to

Include self-weight Automatically includes the self-weight of parts in load combinations. This means that you do not have to model self-weight loads separately. See Automatic loads and load groups (p. 42).

All codes

Generate wind also in opposite direction

If the analysis model has wind loads from a specific direction (x or y), select this checkbox to include wind loads from the opposite direction (-x or -y).

All codes

To automatically include seismic loads in load combinations, use the Seismic and Seismic masses tabs in the Analysis Model Properties dialog box. See also Seismic analysis (p. 80).

If the analysis model has imperfection loads, Tekla Structures automatically creates load combinations with both the positive and negative directions (x and -x, or y and -y).


1. In the Load Combinations dialog box, click New... to open the Load Combination Coefficients dialog box.

2. Select a combination type. See Load combination types (p. 84).

3. Enter a unique name for the load combination. Try to make the name as descriptive as possible.

4. Use the arrow buttons to move load groups between the Loads available list and the Combinations table.

5. Modify the combination factors in the Combinations table by clicking a value.

6. Click Apply or OK.

See also Creating load combinations (p. 86) and Automatic load combination (p. 87).

3.4 Working with analysis and design modelsThis section explains how to examine and modify analysis models. Click Analysis > Analysis & Design Models... and use the Analysis & Design Models dialog box.

Topics Checking objects contained in an analysis model (p. 90)

Adding or removing analysis objects (p. 90)

Showing analysis models and support conditions in model views (p. 90)

Analysis model status (p. 93)


Analysis and Design

Running analysis (p. 93)

Viewing analysis results (p. 94)


Analysis > Analysis & Design Models... (p. 95)

Checking objects contained in an analysis model

To check which parts and loads an analysis model contains:


2. In the Analysis & Design Models dialog box, select a model.

3. Click the Select objects button. Tekla Structures highlights and selects the parts and loads in the physical model.

See also Showing analysis models and support conditions in model views (p. 90)

Adding or removing analysis objects

As well as changing the properties of an analysis model, you can also modify existing analysis models by adding and removing objects.

To add or remove parts and loads:

1. In the physical model, select the parts and loads to add or remove.



4. To add the objects to the analysis model, click Add selected objects (p. 99).

5. To remove the objects from the analysis model, click Remove selected objects (p. 100).

Showing analysis models and support conditions in model views

You can visually check analysis models in Tekla Structures, and make corrections if needed, before actually running the analysis and using the analysis application. This is particularly useful with large models, when the analysis may take some time.

To have Tekla Structures show an analysis model in a Tekla Structures model view:



3. If the analysis is not yet run, click the Create model button. Tekla Structures creates the analysis model.

4. Click the Show in model button.

Tekla Structures shows the analysis members and their identification numbers, nodes, rigid links, and support conditions using the following colors and symbols:

Adding and removing objects changes the analysis model status to out of date, so you must run the analysis again. See also Analysis model status (p. 93).


Object Color Image

Node Magenta

Rigid link Dark blue

Normal member (Beam) Red

Truss member Green

Truss member – Tension only

Violet

Truss member – Compression only

Yellow

Composite beam Gray

Plate, slab, or panel edge Light blue


Analysis and Design

To hide the analysis model from the model view, right-click the view and select Redraw View from the pop-up menu.

To show all member types and to permanently hide member or node numbers or support conditions from model views, set the following variables to FALSE in Tools > Options > Advanced options... > Analysis & Design:

• XS_AD_MEMBER_TYPE_VISUALIZATION

• XS_AD_MEMBER_NUMBER_VISUALIZATION

• XS_AD_NODE_NUMBER_VISUALIZATION

• XS_AD_SUPPORT_VISUALIZATION

Connected

Supported

To hide the model parts and view only the wire frame analysis model:

1. Double-click the model view.

2. In the View Properties dialog box, click the Display... button.

3. On the Settings tab of the Display dialog box, clear the Parts checkboxes.

4. Click Modify.


Analysis members will appear in red.

See also Checking objects contained in an analysis model (p. 90)

Analysis model status

The Results field in the Analysis & Design Models dialog box shows the status of the analysis model. This can be:

• Up to date

• Not up to date

• Status unknown

• None

Not up to date means that the model has changed. To find out more:

1. Click Analysis > Analysis & Design models....

2. In the Analysis & Design Models dialog box, select an analysis model.

3. Click Details... to open the Details of analysis model status dialog box. This displays the status of the following:

• Calculation

• Load combinations

• Analysis model properties

• Parts

• Loads

• Load groups

The Parts, Loads, and Load groups tabs display information about individual objects based on their ID number.

Running analysis

To run structural analysis on an analysis model:



3. Click Run.


Analysis and Design

The analysis application starts and opens the analysis model. Some analysis applications automatically run the analysis.

Viewing analysis results

Once you have run the analysis, you can view the results. For information on analysis results, see the following topics:

• Get results (p. 101)

• Analysis > Analysis & Design Models... (p. 95)

So that you can perform a visual check, you can have Tekla Structures use different colors to show the utilization ratio of steel parts in the physical model. To do this:

1. Run the analysis.


3. In the Analysis & Design Models dialog box, select an analysis model.

4. In the Model Editor, click View > Representation > Object Representation....

5. In the Object Representation dialog box, select the object group whose utilization ratios you want to show.

6. In the Color column, select Color by analysis utility check....

7. In the Utility Ratio Ranges dialog box, set the ranges of ratio for each of the colors that Tekla Structures uses to show safe and unsafe parts.

8. Click OK. Tekla Structures shows the utilization ratio of the steel parts in the selected analysis model using the following colors:

3.5 Analysis and design referenceThis section consists of the reference pages for the analysis and design commands.

Use the commands on the Analysis menu to work with analysis and design models. The following table lists the analysis and design commands and gives a short description of each one.

To show the utilization ratio of steel parts in a report, add the AD$$UtilityRatio template field in the report template you use.


Analysis > Analysis & Design Models...

Synopsis This command displays the Analysis & Design Models dialog box so that you can work with the analysis and design models.

Description The Analysis & Design Models dialog box lists all existing analysis and design models. Use this dialog box to view, add, modify, run, update, and delete analysis and design models. The properties in the dialog box are:


Analysis > Analysis & Design Models... (p. 95)

Displays the Analysis & Design models dialog box so that you can work with analysis and design models.

View Analysis Parts (p. 102)

Shows the analysis parts superimposed on the physical parts in all model views.

Geometry Settings... Displays the Analysis Geometry Settings dialog box where you can define the automatic settings of analysis model geometry. See also Analysis model geometry (p. 67).

Connect Parts Connects the selected parts in the analysis. See also Connecting or disconnecting parts in analysis (p. 70).

Disconnect Parts Disconnects the selected parts in the analysis. See also Connecting or disconnecting parts in analysis (p. 70).

Edit Part Connectivity... Displays the Analysis Member Connectivity dialog box of a selected parts so that you can view, define, and modify the analysis connections of the part. See also Defining analysis connections of parts (p. 71).


Resets the selected parts to the default analysis model geometry settings. All manual adjustments in geometry are removed.


Analysis model name

A unique name for the analysis model. User-definable.



The analysis application or format used in the analysis of the analysis model.

Analysis application (p. 12)


Analysis and Design

Usage The following table explains the functions of the buttons in the Analysis & Design Models dialog box:

Creation method

Defines which objects are included in the analysis model.

Objects in an analysis model (p. 76)

Results Indicates whether the analysis model is up to date or not.

Analysis model status (p. 93)

Number of parts The number of physical parts included in the analysis model.

Members, elements, and nodes (p. 13)

When you create an analysis model using the Full model option, the number of objects in the Analysis & Design Models dialog box changes only when you update the analysis model.


Button Description

New... Displays the Analysis Model Properties dialog box so that you can create new analysis models. See New... (p. 97).

Delete Deletes the selected analysis model.

Properties... Displays the properties of the selected analysis model. See Analysis model properties (p. 74).

Select objects Highlights and selects the parts and loads that are included in the analysis model in the physical model. See also Checking objects contained in an analysis model (p. 90).

Add selected objects

Adds the parts and loads that are selected in the physical model to the selected analysis model. See Add selected objects (p. 99).

Remove selected objects

Removes the parts and loads that are selected in the physical model from the selected analysis model. See Remove selected objects (p. 100).

Show in model Shows the analysis members and their identification numbers, nodes, rigid links, and support conditions of the selected analysis model in the active Tekla Structures model view. See Showing analysis models and support conditions in model views (p. 90).

Update and show Same as Show in model but first updates the analysis model with changes in the physical model, analysis model geometry, or analysis properties of parts.

Load combinations...

Displays the load combinations in the selected analysis model. Also use to create new load combinations. See Load combinations... (p. 100).

Refresh Updates the information on the analysis model list.


See also Working with analysis and design models (p. 89)

New...

Synopsis This command displays the Analysis Model Properties dialog box and creates a new analysis model.

Preconditions Create the physical and load models.

Define the support conditions for parts and connections.

Description Tekla Structures creates the analysis model using the properties in the Analysis Model Properties dialog box.

To automatically include all the objects in the physical and load models in the analysis model, use the Full model creation option.

To create an analysis model for specific parts and loads, select the objects to include in the model, or fit the work area to include them.

Details... Displays detailed information about the status of the analysis model. See Analysis model status (p. 93).

Run Runs the analysis on the selected analysis model.

Create model Constructs an analysis model, but does not run the analysis. Use with the Show in model button when visually checking the analysis model. See also Showing analysis models and support conditions in model views (p. 90).

Open application Starts the analysis application and opens the selected analysis model in it.

Close application Use to exit the analysis application.

Get results Saves the maximum axial force, shear force, and bending moment at the part ends as user-defined attributes in the part properties. To view these results, open a part’s user-defined attributes dialog box.

See Get results (p. 101).

Get results for selected

Same as Get results but only saves results for the selected parts.

Close Closes the Analysis & Design Models dialog box.

Button Description

Whichever creation method you choose, you can use the Filter list box to specify which objects to include in the analysis model. See also Filtering objects.

You can also later add and remove analysis objects. See Add selected objects (p. 99) and Remove selected objects (p. 100).


Analysis and Design

Field/Tab Description More information


The analysis application or format used in the analysis of the analysis model.

To use the same application or format by default for other new analysis models, select the Set as the default checkbox.

Analysis application (p. 12)

Analysis model name

A unique name for the analysis model. User-definable.


Modal analysis model checkbox

Defines whether modal analysis properties are used instead of static load combinations.


Creation method

Defines which objects are included in the analysis model.

Objects in an analysis model (p. 76)

Analysis model filter (p. 77)

Member axis location

Defines which line is used as the axis of each analysis member.

Member axis (p. 77)

Node definition

Defines how the nodes and node positions are defined.

Defining nodes (p. 78)

Extended clash check checkbox

Toggles extended clash checking on and off.

Nodes connecting members and elements (p. 38)

Model merging with analysis application

When changes occur in the analysis model, defines whether:

• The node and member numbers are kept unchanged.

• The model in the analysis application is updated.

Model merging with analysis applications (p. 79)

Member end release method by connection

Defines whether the support conditions of connections or parts are used.

Member end connectivity (p. 78)

Analysis method

Defines whether second order stresses are taken into consideration.


Maximum iterations

Tekla Structures repeats second order iteration until it reaches one of these values.Accuracy

Job Defines the job information in reports.

Contents of STAAD.Pro results files and reports (p. 82)

Output Defines the contents of the analysis results file.


Usage Click Analysis > Analysis & Design Model... to open the Analysis & Design Models dialog box.

To create a new analysis model of the entire physical and load models:

1. Click New....

2. In the Creation method list box, select Full model.

3. Enter or modify the remaining analysis model properties.

4. Click OK.

To create a new analysis model for specific parts and loads:

1. Select the objects you want to include in the analysis model, or fit the work area to include them.

2. Click New....

3. In the Creation method list box, select By work area, By selected parts, By selected parts and loads, or Floor model by selected parts and loads.

4. Enter or modify the remaining analysis model properties.

5. Click OK.

See also Analysis > Analysis & Design Models... (p. 95)

Working with analysis and design models (p. 89)

Add selected objects

Synopsis This command adds parts and loads to the selected analysis model.

Preconditions Create an analysis model.

Description Use this command when you have created analysis models using the By selected parts or By selected parts and loads method.

Usage 1. Click Analysis > Analysis & Design Models....

2. Select the analysis model you want to add objects to.

3. Select the objects to add.

4. Click Add selected objects.

See also Remove selected objects (p. 100)


Seismic tab Properties required by seismic analysis.

Seismic analysis (p. 80)Seismic

masses tab

Modal analysis tab

Properties required by modal analysis.


Design code Design codes for different materials.

Design codes and methods (p. 82)

Design method

The material-specific principle used to compare stresses and material capacities.

Field/Tab Description More information


Analysis and Design

Remove selected objects

Synopsis This command removes parts and loads from the selected analysis model.

Preconditions Create an analysis model.

Description Use this command when you have created analysis models using the By selected parts or By selected parts and loads method.

Usage 1. Click Analysis > Analysis & Design Models....

2. Select the analysis model you want to remove objects from.

3. Select the objects to remove.

4. Click Remove selected objects.

See also Add selected objects (p. 99)


Load combinations...

Synopsis This command opens the Load Combinations dialog box so that you can work with load combinations.

Preconditions Set the code to follow in load combination in Tools > Options > Options... > Load modeling > Current code.

Create an analysis model.

Description

Usage To create load combinations:


2. In the Analysis & Design Models dialog box, select an analysis model and click Load combinations....

3. In the Load Combinations dialog box, click Generate... to open the Load Combination Generation dialog box.

4. Select the checkboxes against the combinations you want to create. See Load combination types (p. 84).

5. To automatically include the self-weight of parts or wind loads from the opposite direction, select the appropriate checkboxes. See Automatically including loads in combinations (p. 88).

6. Click Apply or OK. Tekla Structures creates the load combinations based on the selected building code.



Load combination (p. 83)

Get resultsSynopsis The Get results and Get results for selected commands save the maximum axial force, shear

force, and bending moment at the part ends as user-defined attributes in the part properties.

When you click Get results or Get results for selected and then save the model, Tekla Structures saves the analysis results of all load combinations in a database, analysis_results.db5, in the current model folder.

Preconditions Use the following variables in Tools > Options > Advanced Options... > Analysis & Design to define the analysis member points whose results are saved in the database:

• XS_AD_MEMBER_RESULT_DIVISION_COUNT

• XS_AD_MEMBER_RESULT_DISP_DIVISION_COUNT

• XS_AD_MEMBER_RESULT_MIN_DISTANCE

• XS_AD_MEMBER_RESULT_GRID_SIZE

Run the analysis.

Description

To view the results, open the user-defined attributes dialog box for the part.

To access the analysis results database, use the .NET or Excel design interface.

If you do not want to create the analysis results database, set XS_AD_RESULT_DATABASE_ENABLED to FALSE in Tools > Options > Advanced Options... > Analysis & Design.

Usage To save the results of an analysis model as user-defined attributes:


2. Select the analysis model.

3. Click Get results.

To save the analysis results of specific parts in an analysis model as user-defined attributes:


2. Select the analysis model.

3. Select the parts in the physical model.

4. Click Get results for selected.

To create your own load combinations and use combination factors that are not code-specific, click the New... button in the Load Combinations dialog box. See Manual load combination (p. 88).


Get results Saves the results for each part in the selected analysis model.

Get results for selected Saves the results for the parts that you select in the physical model.


Analysis and Design

See also Viewing analysis results (p. 94)

View Analysis Parts

Synopsis Shows the analysis parts superimposed on the physical parts in all model views.

Usage To switch View Analysis Parts on or off, click Analysis > View Analysis Parts.

A check mark next to View Analysis Parts on the Analysis menu indicates that the analysis parts are already visible.

See also Analysis part properties (p. 72)

Reset Geometry for Selected Parts

Synopsis Resets the selected parts to the default analysis model geometry settings. All manual adjustments in geometry are removed.

Preconditions Use this command if you have modified analysis model geometry by moving, connecting, or disconnecting analysis parts.

Usage 1. Select the parts to reset.

2. Click Analysis > Edit Geometry > Reset Geometry for Selected Parts.



Index

aadding nodes................................................................ 34analysis and design

overview ................................................................ 67prior to ................................................................... 13

analysis and design models ......................................... 95analysis application ...................................................... 11

merging models..................................................... 79analysis member offsets............................................... 18analysis members

properties ........................................................14, 28analysis method .....................................................40, 80analysis model geometry.............................................. 67

modifying............................................................... 70resetting .............................................................. 102

analysis model geometry rules..................................... 68analysis models............................................................ 11

a closer look .......................................................... 37adding or removing objects ................................... 90checking objects.................................................... 90creating ...........................................................74, 97creating geometry rules......................................... 68defining geometry.................................................. 67filtering objects ...................................................... 77modifying.........................................................74, 90modifying geometry............................................... 70objects................................................................... 76properties .............................................................. 74resetting geometry .............................................. 102running analysis .................................................... 93seismic loads......................................................... 80status..................................................................... 93viewing results....................................................... 94

analysis partsproperties .............................................................. 72viewing ................................................................ 102

analysis settings ........................................................... 37applying loads to parts ................................................. 50area load ...................................................................... 60attaching

loads to parts......................................................... 50

automatic loads ............................................................42in load combinations..............................................88seismic loads.........................................................80self-weight .............................................................42wind load ...............................................................63

bbounding box ................................................................50buckling length..............................................................29

ccolor by analysis type ...................................................16color by analysis utilization check.................................94combination factors ......................................................84combining loads............................................................83common nodes .............................................................38compatibility of load groups ..........................................43components

in analysis..............................................................22slabs in analysis ....................................................23

composite beam ...........................................................24connecting parts in analysis .................................. 70, 71creating

analysis models .............................................. 74, 97load combinations .................................................86loads......................................................................56

ddefining

load groups............................................................44nodes.............................................................. 37, 78support conditions .................................................26

degree of freedom ........................................................25deleting

load groups............................................................44design codes and methods...........................................82design information ........................................................27


disconnecting parts in analysis .............................. 70, 71distributing loads...........................................................49DOF

see degree of freedom ..........................................25

e

effective buckling length ...............................................29elements .......................................................................13

ffilter

in analysis models .................................................77filtering

analysis model objects ..........................................77

g

geometry rules of analysis models ...............................68geometry settings of analysis models...........................67

hhandles

of loads ..................................................................54

iintermediate analysis members ....................................28intermediate nodes .......................................................34iteration .........................................................................80

kKmode ..........................................................................29

lline load ........................................................................59

load combination...........................................................83automatic ...............................................................87code .......................................................................39creating combinations............................................86factors ............................................................. 39, 84manual ...................................................................88properties...............................................................83types ......................................................................84

load forms .....................................................................48load groups ......................................................41, 42, 56

automatic ...............................................................42compatibility ...........................................................43defining ..................................................................44deleting ..................................................................44modifying ...............................................................44properties...............................................................43

load model ............................................................. 11, 41load modeling code.......................................................39load types......................................................................46loads ...................................................................... 41, 56

applying .................................................................50attaching ................................................................50automatic ...............................................................42bounding box .........................................................50combining ..............................................................83creating ..................................................................56distribution .............................................................49forms......................................................................48grouping.................................................................42in analysis ..............................................................39load panel ..............................................................52magnitude ..............................................................49modifying ...............................................................53properties...............................................................45scaling in model views ...........................................54seismic...................................................................80types ......................................................................46wind load generator ...............................................63

longitudinal member offset............................................18

mmember analysis type ...................................................16member axis

of all parts in analysis model..................................77of individual parts...................................................17

member end connectivity ..............................................78member end release method ........................................78members .......................................................................13

keeping numbers ...................................................79properties........................................................ 14, 28


mergingmodels with analysis applications ......................... 79

modal analysis.............................................................. 81modifying

analysis model geometry ...................................... 70analysis models...............................................74, 90load groups ........................................................... 44loads...................................................................... 53

nnodes......................................................................13, 38

adding ................................................................... 34defining............................................................37, 78keeping numbers................................................... 79

ppartial safety factors ..................................................... 84parts

analysis properties ................................................ 72physical model.............................................................. 11plates

in analysis ............................................................. 18point load...................................................................... 58

rreduction factors........................................................... 84rigid links ................................................................35, 78running analysis ........................................................... 93

s

safety factors ................................................................84scaling

loads in model views .............................................54seismic analysis............................................................80seismic loads ................................................................80self-weight ....................................................................42slabs

components in analysis .........................................23spanning

of loads..................................................................52of plates.................................................................20

split nodes ....................................................................34strain...................................................................... 49, 62support conditions ........................................................25

defining..................................................................26

ttemperature load ................................................... 49, 62

u

uniform load..................................................................61user-defined attributes..................................................31utilization ratio...............................................................94

vviewing

analysis parts ......................................................102

wwind load generator ............................................... 55, 63

271083916 tekla-15-analysis-manual

Engineering