b2b tutorial
DESCRIPTION
BridgeTRANSCRIPT
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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