b2b tutorial

midas Civil Tutorial 2Prestressed Concrete Bridge

Bridging Your Innovations to Realities

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Contents

1. Project Information

2. Definition of materials

3. Definition of Sections

4. Definition of Time dependent Materials

5. Creating the geometry

6. Boundary Conditions

7. Loads

8. Moving Load

9. Construction Stage Analysis

10. Results

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1. Project Information

63m

16m

Perspective view

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2. Definition of materials

In midas Civil materials can be added at any point in time as well as through different commands. However the most

commonly used is : Properties -> Material Properties -> Material (tab)

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2. Definition of materials

Here, by pressing ADD a new dialog box pops up. Fill this in as shown below:

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After pressing apply this material will appear in the list for materials and you can add in the next one for the steel tendons

as shown below:

2. Definition of materials

Material ID Name Type

1 C50/60 Concrete

2 Y_1670S7(15.2mm) Steel

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3. Definition of Sections

Now that the materials are defined, the sections will be defined in the next step. This can be done in the Section

tab by pressing Add and selecting the PSC tab. Here fill in the dialog box as shown below:

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3. Definition of Sections

Similarly for the shallow section:

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3. Definition of Sections

For the pier section go to the DB/User tab, fill in the data as shown below and press OK:

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Works Tree

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4. Definition of Time dependent Materials

Time dependent material effects can be defined from the Time Dependent Material tab:

1) First defining creep and shrinkage:

By clicking on show results, you can check the creep coefficient and

shrinkage strain graphs as shown below:

50,000

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4. Definition of Time dependent Materials 11

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The variation of compressive strength will be defined as shown below :

4. Definition of Time dependent Materials 12

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4. Definition of Time dependent Materials

Now, in order to connect these properties to our material, a Material link will be generated as

shown below:

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4. Definition of Time dependent Materials

Goto Analysis > Construction Stage to check on Initial Tangent Displacement for Erected Structures

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5. Creating the geometry

First create a node, this you can do from: Node/Element ->Create Nodes

Fill in the pop up dialog box as shown below: In order to create the deck, this node will be extruded into line elements.

Using the select single tool, select the node by drawing a box around it.

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5. Creating the geometry

Next in order to obtain the line elements, the extrude feature shall be used from

Node/Element -> Extrude:

To obtain an appropriate mesh for the 63m deck this will be

broken down into 3m long elements. In order to obtain this, fill

in the dialog box as shown below:

By pressing apply the following can be seen

Zoom fit can be done by pressing icon

:

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5. Creating the geometry

Now, to create the pier at mid point, select the middle element and divide this in two. You can select the middle element by ID

from the Element Selection box. This can be done from : Node/Element -> Divide

Then simply fill in the dialog box as shown below (it has these options by default so you only need to press apply)

The Span has 21 elements and you can choose element number 11 to divide.

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5. Creating the geometry

As a result this will change to:

This node will be copied down by 6.5m (which is the depth of the diaphragm). First select the node using the

select single option then go to: Node/Element -> Translate (within the node tab NOT elements)

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And fill in the dialog box as shown below:

5. Creating the geometry

Once the node is created in order to obtain the pier, this will be extruded by 16m using element lengths of 2 m.

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5. Creating the geometry

Select the node, go to: Node/Element -> Extrude Elements and fill in the dialog box as shown below:

Change section type to 3: Pier

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5. Creating the geometry - Tapering of sections

In order to taper this bridge 2 tapered sections will be created. This can be done from

Properties -> Section Properties -> Add -> Tapered Tab

For the left side of the taper import the 'span' section for 'Size-i'

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5. Creating the geometry - Tapering of sections

Scroll down and import 'diaphragm' for 'Size-j'

then finally change the offset to Centre-Top by clicking on Change Offset... as shown below

Similarly create taper right, however in this case 'Size-i' will be the Diaphragm section and 'Size-j' the

Span section.

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5. Creating the geometry - Tapering of sections

Once you have these two sections, turn on the element number and select elements 1 to 10 by

putting this into the select elements window as shown below:

For these selected elements just simply drag and drop Left taper from the works tree. This will

taper your elements one by one.

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5. Creating the geometry - Tapering of sections

However to create a continuous tapering, select the elements 1 to 10, for which a tapered group will

be created. Go to Properties -> Tapered Group

In the pop up dialog box just simply add in a name and press add as shown below:

Once this is done the tapering will be finished

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5. Creating the geometry - Tapering of sections

Now repeat the same procedure on the right hand side for elements 12 to 21 and naming the group

Right taper. Once tapering is done on both sides this is what the bridge will look like:

As we do not need the element numbers anymore, this can be deactivated

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5. Creating the geometry - Groups

There are various groups in midas Civil these include: Structural, Boundary, Load and Tendon Groups

To ease our work or for the purpose of construction stage analysis we need to create groups

These groups can be found under the groups tab in the Tree menu.

Right click on Structure Group and click on New...

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5. Creating the geometry - Groups

Then add in Pier as the last group without specifying any suffixes:

Similarly the Boundary and

Load groups can be created

so to obtain the following

groups:

Add in Deck with specifying 1 to 4 suffixes:

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5. Creating the geometry - Groups

Assigning elements to structure groups

Select elements 7to15 22, in other words the diaphragm and 4 segments on each side:

For these elements simply drag and drop Deck 1, you will see these elements being assigned to this

group :

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5. Creating the geometry - Groups

Similarly the next two segments on each side will be added to Deck2 :

The same procedure is repeated for the other four segments, they are added in 2 by 2 into Deck3

and Deck4.

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5. Creating the geometry - Groups

Finally the pier elements are added to the Pier structural group (to select these elements you can simply double click on the Pier section from the works tree and all the elements which have the Pier section assigned to them, will be selected)

Once the pier is added to the structure group, you have completed Structure Group:

At this point you should have a model equivalent to: 1 - Groups Created

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6. Boundary conditions

To provide stability for our structure and to represent the actual conditions in which this is, we need

to provide boundary conditions.

Supports

For the definition of Side Support select the two end nodes of the deck. To make this selection

easier, turn off the hidden view:

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6. Boundary conditions

Select the two end nodes and go to: Boundary -> Define Supports and fill in the dialog box as shown

Press apply and the following can be seen:

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6. Boundary conditions

Similarly the Pier Support is defined. For this select the node at the bottom of the pier and fill in the

boundary dialog box as shown below:

Press apply and the following can be seen:

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Links

To provide connectivity between the deck and the pier in the rigid zone a link needs to be created

between the node at the top of the pier and mid point. For this go to Boundary -> Elastic Link, change

the link type to RigidScroll down and click on '2 Nodes'. Now select

the two nodes (top of pier and mid point of deck)

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7. Loading

In midas Civil, loading works the following way:

1) Load cases are defined

2) Loads are assigned to these load cases

Definition of load cases

Go to Load -> Static Load Cases, here you can define all your load cases by defining their name,

type and then pressing add:

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7. Loading

In the same manner the following load cases are added in:

Make sure all load types are Construction Stage Load

At this point you should have a model equivalent to: 2 – Boundaries and Load Cases

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7. Loading

Self Weight

Go to Load -> Self Weight and fill in the pop up dialog box:

By pressing add, the self weight will

appear in the window as shown below:

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7. Loading

Surfacing

For defining the surfacing load select the main deck and apply a Beam Element Load. For this go to:

Load -> Element Beam Load as shown below:

1. Select all the elements for Deck2. Load case/group name : Surfacing3. Enter a value of -5 in the Global Z direction4. Press apply

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7. Loading

To clear the screen press initial view on the right side of the screen

Form traveller and wet concrete load

These two can be defined the same way by using nodal loads. Starting with the wet concrete loading, go to Load -> Nodal Loads

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7. Loading

First select the node and then in the dialog box select the load case, load group name and fill in as

shown below:

By pressing 'apply' the Force and the Moment will

be applied to the node. Using this procedure all

wet concrete and form traveller loads can be

applied. However these loads can be input into

excel and applied to the model from there.

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7. Loading

Here you can see the above loading after the dialog box was closed:

The values for this can be displayed by right clicking on the load and press display:

This can also be checked in a tabular format as well

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7. Loading

Using this table, the loads, moments and groups can be defined for each node as shown in the Excel

table below:

First, delete the loading you have

defined for node 7, and then by

copying this table from Excel into the

Nodal loads table the following can

be seen:

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7. Loading

Looking in the works tree, the Form traveller loads and Wet concrete loads are all defined:

At this point you should have a model equivalent to: 3 - Loads - No Prestress Loads Added

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7. Loading

Tendons and prestress

When it comes to tendons, first the tendon property must be defined which can be done from:

Here press Add in the

pop up dialog box

In the next dialog box, click on the 3 dots to define the tendon area and a small dialog

box appears where you can specify the strand diameter and the number of strands:

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7. Loading

Fill in the rest of the dialog box as shown below:

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7. Loading

Creation of tendons

To create the tendons go to: Load -> Temp/Prestress -> Tendon Profile

The following dialog box appears, fill this in as

shown. Also select the elements to which you want

to assign the tendons or put this in the Assigned

Elements field :

By pressing OK, the tendon will be generated:

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7. Loading

We will be creating 3 more tendons. Please create the tendons using the dialog box as shown:

Make sure element 12to22 are assigned for tendon 3 and 4. Also, Make sure the Profile insertion point is changed

to 22. Similarly tendon 4 will start from element 22 as well.

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7. Loading 48

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7. Loading

Once all four tendons are added in:

Now all four will be copied down by 0.5m. For this, the copy

option will be used within the tendon profile dialog box, first

select all the tendon you want to copy (in this case all four of

them) and then press Copy/Move. Here fill in the dialog box

as shown right:

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7. Loading

Once you press OK, all four tendons are copied down by 0.5m, the dialog box and the tendons appear as shown below:

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7. Loading

Apply prestress:

Go to Load -> Temp./Prestress -> Tendon prestress

Change the units from the bottom right part of the screen. In this case it's beneficial changing into N

and mm rather than using kN and m.

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7. Loading

Once the units are changed in the dialog box change the Load case and the load group names fill in

the dialog box as shown below:The prestress added in will appear in the model

and also will be added into the window above the

Add button

At this point you should have a model equivalent to: 4 – Loads – Including Prestress Loads

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8. Moving Load

Adding in Moving Loads in midas Civil is a 3 step procedure:

1) Define lanes

2) Add vehicles

3) Connect the lanes to the vehicles through moving load cases

First specify the code to be used from Load -> Moving Loads-> Moving Load Code

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8. Moving Load

Definition of lanes

Go to: Load -> Moving Load -> Traffic Line Lanes -> Add

Change the units back to m at the bottom right part of the screen. In midas Civil the definition of lanes happens with an eccentricity from a reference line

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8. Moving Load

Following this, fill in the dialog box as shown:

For the Selection by keep the option as 2 points, then click on the two ends of your bridge, this way the software will define the

reference line from which your lane will be positioned at a distance defined in the eccentricity field.

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8. Moving Load

Press Apply and you will see your lane being defined:

When defining the next lane delete the information the software used to create the previous lane.

For this simply click on No, and hit Delete

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8. Moving Load

Similarly create lanes 2,3 and 4. The eccentricities for these are -1.5, 1.5 and 4.5m respectively.

Once this is done, the lanes look as shown below:

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8. Moving Load

Vehicle definition

To define these go to Load -> Moving Load -> Vehicle -> Add Standard

Here the adjustment factors can be changed for LM1 .

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8. Moving Load

By pressing apply the vehicle type can be changed, and LM3 can be defined:

Press ok and the second vehicle will be defined.

Looking at the works tree the following

should be defined:

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8. Moving Load

Moving Load cases

Go to Load -> Moving Load -> Moving Load Case

Here fill in the dialog box as shown below:

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8. Moving Load

Add in another moving load case as shown below:

By pressing OK The works tree will

change as shown below:

At this point you should have a model equivalent to: 5 – Moving Loads

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9. Construction Stage Analysis

As mentioned previously the groups will be used for the definition of the Construction Stages (CS)

To start defining these go to: Load -> Construction stage -> Define C.S. -> Add

In the dialog box that appears the duration will be defined as well as different Element, Boundary and

Load groups will be activated. Fill in the dialog box as shown below.

28 days 100%

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9. Construction Stage Analysis

With this the first construction stage is done.

The following construction stages are described below in the table:

Stage Duration Element Boundary Load

CS2 10Deck2

Age 7

Activate:Wet Concrete2, Form Traveler2

Deactivate: Wet Concrete1,Form Traveler1

CS3 10Deck3

Age 7

Activate:Wet Concrete3, Form Traveler3

Deactivate: Wet Concrete2,Form Traveler2

CS4 10Deck4

Age 7Side Supports

Activate:Wet Concrete4, Form Traveler4

Deactivate: Wet Concrete3,Form Traveler3

CS5 10000Activate: Surfacing

Deactivate: Wet concrete4, Form Traveler4

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9. Construction Stage Analysis

The construction stages can be check through the CS dropdown box in the modelling space:

Once this is done, perform the analysis. When done the software will indicate the analysis was

completed successfully in the message window:

At this point you should have a model equivalent to: 6 – Final Model

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10. Results

All results can be checked in each construction stage for various load cases. Starting with the

reactions, go to Results -> Reactions -> Reaction Forces/Moments

Change to the CS which you would like to check and select the load case you want to check the

results for. For these the values and the legend can be displayed :

By pressing Apply the results can be checked

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10. Results

Similarly Displacements can be checked from: Results -> Deformations -> Displacement Contour

Bending Moments can

be checked from:

Results -> Forces ->

Beam Diagrams

Correction to be made

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10. Results

Stress results can be checked from Results -> Stresses -> Beam Stresses (PSC)

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10. Results

Tendon Stress Losses (Results -> Results Tables -> Tendon -> Tendon Loss)

Here tendon stress losses can be checked in a tabular format:

Correction to be made

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10. Results

This can also be checked in a graphical format from the Tendon Loss Graph:

Correction to be made

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10. Results

Using the moving load tracer the software will generate the worst live load distribution for a particular

position in the structure and a given effect. This can be checked only in the Post Construction stage.

These moving load results can be checked using the Moving Load Tracer from : Results -> Moving

Load -> Moving Load Tracer -> Beam Forces Moments

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10. Results

By clicking on Key Element the window turns green and you can simply click on the element of interest. By pressing Apply the influence lines and load distribution can be obtained

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