effective design of structural steel using autodesk®...

Effective Design of Structural Steel Using Autodesk®

Revit® Structure 2012 David J. Odeh, PE, SECB – Odeh Engineers, Inc.

Handout co-authored by Henry Jackson, Odeh Engineers, Inc.

SE6588-L In this hands-on lab, we will explore the structural steel analysis and design Autodesk

Extensions for Revit Structure 2012, with particular emphasis on using the extensions for productive

design and analysis of steel-framed floors. We will start with an overview of the Autodesk Extensions and

explain how they work with the Revit Structure analytical model. Next, we will review the features and

functions of the Composite Design, Floor Vibration Analysis, and Gravity Column Designer extensions.

We will also explore some features of extensions for 2012, including analysis of cantilevered beams.

Lastly, we will apply these Revit Extensions to some real-life example problems from steel-framed

buildings. You will see how you can be more efficient in designing steel-framed buildings using this tool.

Learning Objectives At the end of this class, you will be able to:

Describe the features and functions of the Revit steel-framing design extensions

Create efficient steel-framing designs directly inside of Revit Structure 2012

Explore design concepts for steel-framing systems

Enhance productivity using the steel design extensions in Revit Structure

About the Speaker

David Odeh is vice president and principal at Odeh Engineers, Inc. He is responsible for a wide range of

structural design and analysis projects, and oversees many major projects executed by the firm. Over the

last five years, he has helped manage the firm's transition to BIM technology for most of its design work.

David is also part of the adjunct faculty of Brown University in Providence, Rhode Island, and regularly

lectures at other universities, including the Rhode Island School of Design (School of Architecture),

Harvard Graduate School of Design, and at professional conferences. David is an active participant in

engineering professional societies, and serves as the co-chair of the Joint National Committee on

Building Information Modeling of the ASCE Structural Engineering Institute and Coalition of American

Structural Engineers (CASE).

Henry Jackson, co-author of the handout, is a structural software engineer at Odeh Engineers, Inc.

Henry develops tools for structural engineers to improve productivity of their design workflow. He also

works on building design projects to perform structural analysis, develop conceptual structural designs,

create construction models, and coordinate multi-disciplinary design models. He is a graduate of Brown

University in civil/structural engineering.

Effective Design of Structural Steel Using Autodesk® Revit® Structure 2012

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About This Handout This handout is designed to give an overview the structural steel design extensions available with Revit

Structure, as well as serve as a tutorial for a hands-on lab. The handout is broken down into three

sections:

Part 1: Introduction and overview of the extensions (page 3)

Part 2: Hands-on lab tutorial (page 5)

Part 3: Example case studies (page 27)


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Part 1: Introduction & Overview Many structural engineering firms have adopted Autodesk Revit Structure to improve the productivity and

efficiency of their practices. Using Revit Structure, engineers can create a single building information

model (BIM) that can be used for many purposes, including construction documentation, detailing, and

coordination with other disciplines.

Revit Structure also generates a so-called “analytical model” that can be used to link with other external

analysis tools, such as Autodesk Robot Structural Analysis, or to perform design and analysis functions

directly inside of the model using the Autodesk Revit Structure Extensions. The Revit Structure

Extensions are particularly useful to structural engineers because they eliminate the need to create and

maintain multiple models for construction documentation and analysis.

This class explores three Revit Structure Extensions for steel framed floor system design and analysis:

the Composite Design extension, the Floor Vibrations Analyzer, and the Gravity Column Designer. These

tools allow the engineer to analyze and optimize steel member sizes, evaluate floor vibrations, and

directly populate the Revit Structure model with calculated design information. Specific applications of

the extensions include: conceptual review of floor framing options, detailed design of new steel framed

floors, and analysis of existing floor systems.

These extensions help engineers be more productive by performing typical daily design tasks directly

within the Revit Structure model, avoiding the need to run separate applications or perform tedious hand

calculations. This handout demonstrates a workflow and some design examples that illustrate the use of

the extensions in a typical structural engineering design office.

NOTE: All content herein is intended to illustrate the use of the design tools within Revit Structure and

does not represent formal design of any specific structure. All concepts and tools discussed in this

handout and presentation are intended to be used by a qualified structural engineer with proper license in

the location of the project. All results and designs computed by the system must be reviewed by a

qualified engineer, who shall be fully responsible for any final design or documentation prepared using

these tools.

Workflow for Floor Design and Analysis The Composite Design Extension (CDE) and Floor Vibrations Analyzer (FVA) were designed to work

together, allowing the engineer to optimize and analyze floor framing that is selected from the Revit

Structure model.

The typical workflow to use these tools consists of the following three steps:

1. Creat the model in Revit Structure, including specification of the floor slabs and initial beam sizes.

Material properties such as steel strength, concrete density, and strength are applied in the Revit

model. Revit creates a parallel “analytical” model automatically. The engineer can manage the

analytical model by creating “Analytical” views (in plan or 3D) and performing adjustments and

consistency checks to ensure that the model is consistent and properly completed.

2. Analyze/Design the Floor Framing for Strength and Deflections using the Composite Design

Extension

Select the area of the floor to be designed or analyzed. For the CDE, the engineer can select

individual members, groups of members, or the entire floor (as long as the floor slab is


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continuous). Typically the CDE will be used first to evaluate the member strengths and static

deflections, followed by a check of vibrations using the FVA.

Initiate the extensions on the “Extensions” tab, under the “Analysis” menu. The extension opens

a new dialog box with the selected members highlighted.

Using the CDE, members can be optimized or checked for both composite and non-composite

action. For composite members, the CDE will check the pre-composite loads and post composite

loads for strength and deflection criteria in accordance with the American Institute of Steel

Construction standards and user settings. Numerous design settings are available to the

engineer to fine-tune the design. The CDE will also analyze and design non-composite

cantilevers and backspans.

3. Check the Design for Vibration Serviceability using the Vibration Analysis Extension. The FVA

analyzes “bays” in the floor framing, either from the user selected members or by inferring them from

the slab that is selected by the user.

The FVA analyzes the floor based on user settings, and it can consider “walking excitation”,

“rhythmic excitation”, and “sensitive equipment vibrations” as recommended in the American

Institute of Steel Construction Design Guide #11 “Floor Vibrations due to Human Activity”.

Bays that do not pass the vibration criteria can be adjusted in Revit Structure and re-analyzed as

required.

Workflow for Gravity Column Design The Gravity Column Designer (GCD) is a simple tool that you can use to analyze or optimize an individual gravity column for loads that you have calculated yourself by hand or that you enter in the Revit Analytical model. 1. Create the Model in Revit Structure.

The GCD allows you to either enter loads directly in the Revit Analytical model (in the form of

unhosted point loads located near the column) or directly in the extension. NOTE: At this time,

the GCD does not calculate tributary loads from other elements, so you need to enter the loads

manually.

Select the column you would like to design. You can select any individual column (NOTE: you

can only design one section of a spliced column at a time using this extension), and activate the

extension using the Extensions ribbon tab.

2. Analyze/Design the Column using the Gravity Column Design Extension

Notice that GCD window reads the column size and loads you input in the analytical model, and

includes all of the levels defined in your model that intersect that column

Click on an individual level of the column to view information about that level (loads and column

fixity). You can add loads with eccentricity as well as applied moments about either bending axis

at each level.

The program automatically updates the interaction equation result (AISC H1-1a or H1-1b) based

on the load and fixity in each direction at the level as you change them.

3. Optimize the Column and Save Back to Revit Model by clicking the “Optimize” button on the

“Summary” screen to select the lightest available section for the loads you have specified. You can

also explore other sizes by changing the member size manually.


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Part 2: Hands-on Tutorial for Structural Extensions

Preparing Revit Model for Structural Analysis Before running the structural extensions, the user must create the Revit Structure model, including

specification of the floor slabs, initial beam sizes, column or wall supports. Material properties, such as

steel strength, concrete density and strength are applied in the Revit model.

Revit creates a parallel “analytical” model automatically. The engineer can manage the analytical model

by creating “Analytical” views (in plan or 3D) and performing adjustments and consistency checks to

ensure that the model is consistent and properly completed.

1. Open first Revit model, AU 2011 Demo 1 - Composite Framing.rvt

2. Navigate to structural plan Level 1, if it is not active

Steel framing has been laid out and assigned dummy sizes. The material assigned to the beams will be

used by the extensions to determine steel properties.

The floor is a composite slab-on-deck with a metal deck profile and a concrete layer. The Revit material's

properties will be used by the extensions to determine concrete stiffness, strength, and density.


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3. Navigate to structural plan Level 1 - Analytical

This view has both the physical and analytical models turned on. You can toggle the analytical and

physical model visibility in the Visibility/Graphics dialog.

Every beam has an analytical representation that can be edited independently from the physical beam if

necessary. This model does not require any analytical adjustments, but the engineer should be aware

that the structural extensions use the analytical model to determine geometry and bearing relationships,

so the consistency of the analytical model is important.

Applying loads to the Revit model Several of the structural extensions read loads that have been modeled in Revit. This section will

describe how to create and modify analytical loads. The Composite Design extension will automatically

include the self weight of the beam and slab, so only superimposed dead loads need to be modeled.

4. Navigate to 3D View Analytical Model. This is a 3D view of the model with only the analytical

model visible.


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5. With the selection tool active, click on the area load applied to the floor. It is represented as a series

of arrows around the perimeter of the floor.

The Properties palette will display the attributes of the load.

This load is a 20 psf dead load (Load Case is DL1, magnitude is -0.02 ksf). Note that gravity

forces are in the negative Z direction.

Revit supports Point, Line, and Area loads. Loads are either Hosted (meaning they follow the geometry of

another member) or unhosted (meaning they can have their own arbitrary geometry).

To apply loads to a floor it is generally easiest to apply a Hosted Area Load to the floor slab. The load will

automatically cover the floor, and will adjust its shape if the floor is edited.

Loads have a single load type (e.g. "dead"), and multiple loads can be overlapped.

6. On the Analyze ribbon tab, select Loads to place a load.

7. On the Modify | Place Loads ribbon tab that activates, select Hosted Area Load (on the far right)

to place a Hosted Area Load

8. In the Properties palette, change the Load Case to LL1 (live load). Change the value for Fz1 to -

0.100 ksf (100 psf).


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9. Apply the load by clicking on the edge of the slab.

Hosted Area Loads are easiest to apply in a 3D analytical view, and the slab must be selected by

clicking its edge.

You will see the new load visible in the 3D view as a series of arrows at the perimeter of the slab.

10. Save the Revit model. We will use this model in subsequent sections.

Run "Composite Design" Extension The Composite Design extension can be used to perform a design and analysis of steel floor framing that

is part of a composite slab-on-deck floor. In this section we will show how to launch the extension and

perform a basic analysis.

11. Use the model from the previous section, or open model AU 2011 Demo 1b - Composite Framing

(Loaded).rvt

12. In the Level 1 structural plan view, select all the beams to be designed (the entire floor).


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13. Launch the Composite Design extension by activating the Extensions ribbon tab and selecting

Analysis → Composite Design.

The Extensions tab is only available if you have the REX Extensions installed.

The Composite Design extension will load all the selected beams, their associated floor slab, and

any relevant loads.


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14. Once the extension has loaded, review the analysis and design settings that the extension uses by

default: select the Edit menu and pick Composite settings. This window contains settings that are

used by the program. You may review the settings, and pick Cancel when you are done (leave the

settings at their defaults for this lab).

15. On the Geometry tab, in the Selection screen, click on the beam along the top edge on the left, if it

is not already highlighted.

Since we are on the Geometry tab, the lower portion of the extension shows geometry data for the

selected member.


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16. Navigate to the Loads tab to view the loads on this member.

Notice that the beam has several lines loads on it due to its own weight, the slab self-weight, and the

applied dead and live loads from Revit. Beam and slab self-weight are automatically determined by the

extension, and are labeled as Material. The superimposed live and dead loads come from the Revit

loads.

17. Navigate to the Design tab.

Since this member has a default size of W8X10, it is undersized for the loads applied. Notice that it is

failing multiple analysis criteria.

18. Change the section size by picking a new designation from the Section drop down. The analysis will

update according to your new selection. You may also check the Composite checkbox to apply studs


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to the beam


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19. To optimize the section, click Design Selected Member. This will select an optimal shape, stud

count, and camber based on the loads and settings.

Notice that the beam section changes and that stud are calculated for the beam. The calculation results

are visible. The color of the beam in the Selection pane also changes from red (failing) to maroon (close

to capacity).

By default, the extension will try to design the beam as a composite member and noncomposite member,

picking the lighter section. You may force the beam to pick a noncomposite member by selecting Design

Non-Composite under the Design Procedure option.

Beams that cannot be designed composite (e.g. they pass through a slab opening or have negative

moment) will not allow a Design Procedure selection other than Design Non-Composite.


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20. Navigate to the Static Calculations tab to see more information about the behavior of the beam,

including moment, deflection and shear plots.

Static calculations are visible for a single load case at a time. The load case defaults to Unfactored, but

you can change it using the Case drop-down menu.

21. Explore the Static Calculations tab. Click on the Beam pane to see a summary of the beam

forces. Dedicated shear, moment, and deflection plots are also available.

22. Return to the Design tab and click Design All Beams to perform an optimization of all beams on the

floor.

23. Once the optimization is complete, you can view results for each beam by clicking on it in the

Selection pane on any tab.

24. You may explore the results for a beam using the Static Calculations, Extreme Results, and

Design tabs.


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25. Click on the Report tab and then the Report pane to view a report of a specific beam.

You may change which sections are include in the report by toggling the checkboxes in the lower

portion of the screen.

You may save a beam report to a variety of formats using the File menu on the Report pane.

26. When you are satisfied with the design, click OK in the Composite Design extension to save all

changes back to Revit. This will update the beam sizes, camber amount (if any), stud count (if any),

and unfactored beam reactions.

If you instead click Cancel to close the extension, no changes are made to the Revit model.

27. Save the Revit model. We will use this model in the subsequent sections.

Run "Floor Vibrations Analyzer" Extension The Floor Vibrations Analyzer extension can be run as an analysis check after preliminary design of the

floor is complete. In this section we will perform a vibrations analysis on the test model. The extension

does not modify the model.


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28. Use the model that was designed by the Composite Design extension in the previous section, or

open model AU 2011 Demo 1c - Composite Framing (Designed).rvt

29. Launch the Floor Vibrations Analyzer from the Level 1 structural plan by selecting the floor slab and

activating the Extensions ribbon tab and selecting Analysis → Floor Vibrations Analyzer.

Unlike the Composite Design which requires you to select individual beams to design, the Floor

Vibrations Analyzer will perform an analysis of an entire floor slab. Selecting beams is not necessary.

Floor vibrations analysis is done using the AISC Design Guide 11 procedure. The procedure

assumes that all beams are simply-supported.

Only rectangular bays are supported by the tool. Note that the trapezoidal bay is ignored.

30. On the main Floor Vibrations Analyzer window, change the Occupancy setting to Indoor (Modular)

The Occupancy setting is used to determine the amount of damping that the architectural details

will provide, and also affects the perception limits of the occupants.

The extension supports three types of analysis: "Walking Excitation" (static footfall analysis), "Rhythmic

Activity" (dynamic analysis), and "Sensitive Equipment" (velocity-limited analysis). One or more analysis

types must be activated to see results.


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31. Navigate to the Analysis tab. Check Walking Excitation to enable that type of analysis.

32. Return to the Floor Plan tab.

The floor bays are now color-coded according to whether they meet the criteria for the occupancy

and analysis types.


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33. Hover mouse over a bay to see bay properties in the sidebar.

Several bays on this floor have unacceptable vibrations, as noted by the red shading. The green bays

pass the analysis check.

Note that some of the bays do not pass the analysis check for walking excitation.

34. One possible solution to a floor that has unacceptable vibrations is to increase the slab weight. Close

the Floor Vibrations Analyzer.

35. In the Level 1 structural plan view, select the floor slab.

The floor slab has a type Composite Floor LW 6.25", which uses lightweight concrete.


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36. With the slab selected, in the Properties palette, change the floor type to Composite Floor NW

6.25". This floor type has the same dimensions but uses normal weight concrete.

37. With the slab selected, relaunch the Floor Vibrations Analyzer (Extensions ribbon tab, Analysis →

Floor Vibrations Analyzer)

38. Set the Occupancy back to Indoor (Modular), and set the analysis type to Walking Excitation.

39. Return to the Floor Plan tab. Note that Bay #2 is now passing the vibrations check (although Bay

#1 is still failing).

40. You may adjust the settings on the Analysis tab to perform different types of analysis.

41. When you are finished, close the Floor Vibrations Analyzer extension and save the Revit model. We

will use this model in subsequent sections.

Cantilever Design and Analysis with "Composite Design" Extension The Composite Design extension is capable of analyzing and designing cantilevers and backspans. In

this section we will demonstrate how to model a cantilever in Revit such that it is recognized by the

Composite Design extension, and then use the extension to perform a design.

42. Use the model that was designed by the Composite Design extension in the previous section, or

open model AU 2011 Demo 1d- Composite Framing (NW Concrete).rvt


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The bay on the right side of the building is not supported by columns at the slab edge. The Composite

Design and Floor Vibrations Analyzer do not perform a vertical load path check, and are not capable of

recognizing this condition. The Composite Design can properly analyzer and design cantilevers but they

must be properly marked as such. The Floor Vibrations Analyzer has no concept of cantilevers.

Cantilever outriggers and backspans can be marked by setting the Moment Connection to Cantilever

Moment for the ends of the beam that are to be connected.

43. Navigate to the Level 1 - Analytical Model structural plan. This view has both the physical and

analytical models enabled.

The Revit analytical model marks the "start" of each beam in green and the "end" of each beam

in red. When adding moment connections, it is important to distinguish between start and end.

44. Select the horizontal beam at the top of the bay in question at the right side of the floor.

Note that the "start" of the beam is at the column. We want to identify this connection as a

cantilever moment connection.

45. With the beam selected, go to the Properties palette and change the Start Connection to

Cantilever Moment and press Apply.


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Note that Revit marks the connection as a moment connection with a triangle.

The physical model must be selected for this setting to be visible. If the analytical model is

selected, the Start Connection and End Connection settings are not available.

There are other settings related to end fixity that can also be set in Revit, e.g. the analytical beam

releases. The Start Connection and End Connection settings are the only ones used by the

Composite Design extension, and only if they are set to Cantilever Moment.

46. Select the horizontal beam at the bottom of the bay and change its Start Connection to

Cantilever Moment as well.

The Composite Design supports cantilevers either as stub outriggers only (no backspan), or allows one or

more backspans to be connected. In the case of a stub outrigger, the beam is assumed to have a fixed

support and that the column it attaches to takes all the moment reaction. The Composite Design does not

design the column for this moment.

Backspans can be specified by using a matching Cantilever Moment where the beam ends meet. The

Composite Design will assume that the beams are moment-connected to each other, and that they do not

transfer any moment to the support.

The user can specify any number of backspans, or may have an outrigger on either side of the backspan.

47. Select each of the backspans and change their End Connection setting to Cantilever Moment.

Note that the "end" of the backspan beams corresponds to the "start" of the outriggers. It is helpful to

view the analytical model while adjusting these settings so that it is clear which is the beam "start"

and "end."

48. Save the Revit model. We will use this model for the next steps, or you may open model AU 2011

Demo 1e- Composite Framing (Cantilevers).rvt

49. Once the two outriggers and two backspans have been marked, select the floor and launch the

Composite Design extension.

Once the Composite Design has launched, you can see an analysis overview of the floor. Many of the

beams may be flagged as failing now, since we increased the slab weight to reduce floor vibrations.

50. Click on one of the outriggers to select it.

Note that the Composite Design also identifies the backspan and highlights it in the plan view.

The Geometry tab shows the cantilever condition of the beam selected.


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51. Navigate to the Static Calculations tab and then click on the Deflections pane.

Since this beam has more than one span, it is subject to live load patterning. The results of the

patterning are visible in this plot.

See the Composite Design help for more information about how the Composite Design uses Live

Load Patterning.

Note that the greatest displacement value for the cantilever does not occur in the fully-loaded

case.


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52. Navigate to the Design tab.

Note that the beam is failing for several reasons.

Note that since this beam has negative moment at its support, it cannot be designed as a

composite beam. The only Design Procedure option that is available for this beam is Non-

composite.

53. Click Design Cantilever System to optimize the outrigger and backspan.

Optimization is always performed for the entire cantilever system, not the individual members.

By default, the Composite Design will pick the same section size for the outrigger and backspan.

You may optionally have the extension optimize the sizes independently, but this option is much

slower. Change that setting in the Composite Settings window.

You may also adjust the section sizes of each beam independently by changing the Section

dropdown. The beam will be re-analyzed if that setting is changed.

54. When you are finished, close the Composite Design extension.


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55. Close the model by picking the Revit menu → Close. We will be using a different model for the next

section

Gravity Column Designer The Gravity Column Designer performs design and analysis of individual columns in Revit. It supports

multi-story columns and will read point loads from Revit. The Gravity Column Designer does not support

column splices or lateral loads.

56. Close any open Revit models and open model AU 2011 Demo 2- Gravity Column Designer.rvt

57. Navigate to the 3D view Analytical Model.

Notice there are several point loads modeled for one of the columns. These point loads can be

modeled in a similar fashion to the area loads applied to the floor slab.

Point loads that lie within 1' of a column are automatically read in when the Gravity Column

Designer is launched. If the load is not exactly along the column, it will be read with an

eccentricity.


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58. Select the column with point loads and launch the Gravity Column Designer by navigating to the

Extensions ribbon tab and selecting Analysis → Gravity Column Designer.

The Gravity Column Designer can only be run with one column at a time.

59. Click on the different Levels in the left sidebar to see the loads and bracing applied at each point.

Fixity and loading can be adjusted at each level.

The Gravity Column Designer only supports single columns, but they can be multi-story. Column

splices are not supported.


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60. At the Level 2 level, add a new Live load with a magnitude of 10 kips, an eccentricity of 8 inches

in the X direction, and no eccentricity in the Y direction by entering it in the Point Loads grid.

Notice that the interaction equation result for that level increases with the new load.

61. On the Summary tab, click the Optimize button to select an optimal section based on the loads and

fixity applied.

62. When you are finished, click OK to save the column designation back to Revit.

If the section you picked was not already loaded in Revit, you may be prompted to pick the Wide-

flange family file.


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Part 3: Example Projects The following examples illustrate real projects for which the Composite Design and Floor Vibrations

Analyzer extensions were used. The extensions are very useful for both new design and evaluation of

existing designs.

Conceptual Design of New Floor – Hospital Outpatient Clinic Building For a new three-story medical outpatient clinic building, several different design options needed to be

considered for the floor framing. The design criteria were established in conjunction with the owner and

architect as follows:

6” floor slabs using 3” composite slab-on-deck construction

Maximum beam/girder depth of 18”

Live load of 100 psf for entire floor

Walking vibration criteria per AISC Design Guide #11

The design engineer created three different bay framing options in a Revit Structure Model (utilizing a

linked Revit Architecture model for the column grids already established by the architect), including beam

layouts, slabs on deck, and preliminary loads . Next, the Composite Design Extension was used to

optimize the beam sizes within the established depth restriction from the architect of 18”. The member

sizes and stud counts were then saved directly back into the Revit Structure model. Each design was

also checked for vibration serviceability using the Floor Vibrations Analyzer extension.

Takeoff analysis of three options for hospital building layout, based on Revit Structure schedule/quantity table


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Finally, a member piece count and steel weight were calculated using the Revit Structure

“Scheduling/Quantities” feature. A graphical summary of the results was prepared for consideration by

the owner and construction manager, upon which the most economical scheme was selected. This

scheme was immediately converted into a production Revit Structure model to begin detailed design.

Analysis of Existing Floor System –Office Building High Density Storage

Installation In this example, a tenant of an existing office building wished to install a high density file storage system,

weighing approximately 250 psf, on an upper floor of the building. The original structural drawings

indicated that the floors, constructed using a composite slab on deck system, were designed for typical

office live loads of 50 psf + 20 psf partition loads. While the high density file storage system would result

in higher loading than these design values, the higher loads would be localized to a limited area of the

floor. A structural analysis was performed to assist the client in locating the storage system so that floor

reinforcement could be minimized or avoided altogether.

Revit Structure model showing loads traced over architectural layout of office space.

To perform the analysis, the engineer first created a Revit Structure model, utilizing AutoCAD background

drawings provided by the owner. Member sizes and stud counts were directly input into the Revit

Structure model from information provided on the original design drawings. The AutoCAD background

drawings also indicated the floor plans with partitions and proposed locations for new storage spaces.

Using the AutoCAD drawing as an overlay in Revit Structure, the engineer sketched the loads in different

areas to simulate the effects of the high density file storage system (superimposed on the other live loads

present in the office and the actual partition loads as measured in the building). Each loading case was

analyzed using the Composite Design Extension to determine if the members met both strength and

deflection criteria. Detailed results were printed indicating member pass/fail status.


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Ultimately, working with the client, a location was selected that required minimal structural reinforcement

to the steel framing.

New Fitness Center and Natatorium In this example, a large steel framed fitness center and natatorium structure was designed using several

third-party software applications. This structure consisted of composite slab-on-deck floors (for the fitness

center), and a long-span steel truss roof system over the natatorium space. The lateral force resisting

system was designed using reinforced masonry shear walls. Due to the hybrid nature of the construction,

several applications were required to perform the analysis and design of the structural elements. Member

sizes and other information were input manually by the engineers into a Revit Structure model in order to

coordinate design with the architect and prepare the final construction documents.

For this project, clearly the extensions would be insufficient to complete the entire design of the structural

framing. However, the Composite Design Extension was used by the project manager to perform a

quality assurance check on the output of the third party software application, as well as the accuracy of

the input to the model. The CDE was run for the entire floor, and rapidly identified any “failed” members

for strength or deflection. In most cases, such members were determined to be input incorrectly or had

changed in span or tributary area at some point after the design was completed in the third party

application. Rather than re-run the entire model through the third party software, these individual

members could be quickly resized using the CDE and checked for adequacy.

Additionally, the FVA was used to check rhythmic vibrations on the floor framing for the fitness center. It

was discovered that the bay sizes resulted in failure of the vibration criteria as initially designed in the

third-party application, and member sizes were subsequently increased and stiffened to meet the

requirements for vibrations.


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Revit Structure model of new Fitness Center (front part of building, with elevated composite floors) and Natatorium (rendering produced in Autodesk 3D Studio Max ™)

The integrated extensions proved to be invaluable tools during detailed design for this project, since they

could be rapidly deployed to check, fine-tune, and resize elements without resorting to a complete re-

analysis using other software.

Summary The Revit Structure Extensions for steel framed floor design apply to both composite and non-composite

floors, and can be used to quickly analyze member strength and serviceability, rapidly explore different

design concepts for floor framing, and create optimum framing designs by weight, cost, or depth. The

Floor Vibrations Analyzer also allows users to evaluate all three vibration serviceability criteria included in

the AISC Design Guide #11 “Vibrations due to Human Activity”. The Gravity Column Designer provides a

quick and easy tool to evaluate individual columns in the model “on the fly”.

The Extensions work directly inside of Revit Structure by reading information from the analytical model,

and saving results directly back into the model file. By using a single model, engineers can often

eliminate the need to create and maintain separate models in third party applications, thus improving their

efficiency in performing daily design tasks. Furthermore, even in complex models where third party

design tools are required, the extensions are a very useful tool for quick design revisions, quality

assurance checking, and review of third-party analysis results for accuracy.

effective design of structural steel using autodesk®...

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