MIDAS steel composite curved bridgetutorial

Click in nodal connectivity field and click on nodes 7,1,4.. Right click on Diaphragm section from Works Tree Menu and select Active.. Create Rigid Link between top and bottom nodes on t

Bridging Your Innovations to Realities

Overview

1 The bridge geometry is made

1 Materials and sections are defined

2 Geometry is made from scratch

3 Crossbeam/ diaphragm modeling

4 Boundary conditions are applied

5 Loading is applied (Self weight and SIDL)

2 Live Loads are applied as per AASHTO LRFD

1 Two lanes is defined

2 The lane can carry vehicles in both directions

3 Analysis

1 Response Spectrum

2 Live load

1 Introduction

• FEA Modeling of Steel Bridges

1 Beam Element (Composite Section)

2 Beam & Plate Elements

6

Properties> Material > Add

Steel:

1 Select Steel under type of design

2 Select ASTM09(S) under Steel

Standard

3 Select A709-50W type from DB

4 Click Apply

Concrete:

5 Select Concrete under type of design

6 Select ASTM(RC) under Concrete

Standard

7 Select C5000 (for pier and pier table)

8 Click Apply

Concrete for Crossbeam:

9 Select C5000 from DB, then Standard

as None

10 Enter Name as Crossbeams

11 Set Weight density as Zero

3 Plug in dimensions as provided

4 Click Change Offset

8

Properties > Section > Add > DB/User

Diaphragm:

1 Select BD/User tab

2 Select ‘I-Section’, and ‘DB’

3 Select AISC(US) under Steel Standard

4 Enter name Diaphragm, as W16X45 from

Properties> Section > Add

Bracing:

1 Select DB/User tab

2 Select ‘Angle Section’, and ‘DB’

3 Select AISC(US) under Steel Standard

4 Enter name as Bracing, and L- 4X4X3/8

from DB

5 Set Offset as Center-Center

6 Click Apply

Pier :

7 Select DB/User tab

8 Select ‘Solid Round’

9 Select User

10 Enter name as Pier

11 Enter Diameter as 72 in

10

Properties> Section Add Section

Pier Cap: (P_L)

1 Select Tapered Section Tab

2 Select Solid Rectangle section for the ends of Pier Cap

3 Enter name as P_L for left end

4 Enter values for i and j

5 Apply y and z axis variation for linear

6 Set Offset Center Top

7 Click Apply Repeat above step s again for the other end of cap(P_R) (i and j

end interchanged) Dummy Crossbeams:

1 Select DB/User tab

2.Select Solid Rectangle

3 Enter name as Dummy Crossbeams

Properties > Thickness

1 In-plane & Out-of-plane: 8 in

2 Check Plate offset

4 Modeling

1 Node/Element > Nodes > Rotate Nodes Rotate nodes at abutment 1 (left side)by 30 º first

2 Then abutment 2 (right side) by - 30º

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1 Node/Element > Elements > Create Line Elements on Curve Create Line Elements on Curve by using

Arc by 3 Points methods Enter 40 for Number of Segments Click in field P1 and then click on nodes from left to right (like nodes 1, 2, 3)

2 Repeat for the other four girders

1

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1 Create diaphragms for Abutment 1 Click in nodal connectivity field and click on nodes 7,1,4

2 Repeat step 1 for diaphragm over Pier Cap and Abutment 2

3 Repeat Step 1 for every 4 th node (diaphragm at pier cap) on inner edge girder with section as Bracing as shown

Over Pier cap Diaphragm Sections

Toggle off Hidden

4 Modeling - End Diaphragm

1 Right click on Diaphragm section from Works Tree Menu and select Active Then Select All and translate

(Node/Element > Nodes>Translate) along Z axis by (0,0,-76.8”), to make the nodes for Bottom chords of

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3 Change element type to Truss and create inverted K- bracings for end diaphragms by snapping nodes at the mid

points of the bottom chord.*

4 Click in Nodal connectivity Click node at top and then move down to the bottom chord, the cursor will

automatically be placed at its mid point, and click there.*

5 Repeat for all end-diaphragms (i.e at pier cap and abutment 2)

* 2 signifies that nodes will be snapped automatically to divide the element into ½ It can be changed to 3,4,5,,,,, to divide element by snapping nodes at 1/3 , ¼,1/5 ,….of element length

At bottom-right corner of midas CIVIL window

3

6 Boundary>Rigid Links Create Rigid Link between top and bottom nodes

on the girder webs at Abutment 1 diaphragm; the bottom node as Master node and top node as Slave node

7 Click in Master node field and then click on bottom node in Model View

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1 Activate All and right click on Bracing section from Works Tree Menu and select Active Then Select by Window the

member corresponding to intermediate diaphragm

2 Click Activate(F2) Select All and Translate nodes (Node/Element > Nodes>Translate) along Z axis by (0,0,-74.4”) , to

make the nodes for the bottom chords of intermediate diaphragms

3 Node/Element > Elements > Create Elements Create bottom chords by connecting the translated nodes using bracing

sections

1

4 Change element type to truss and check off intersect Node and Element and create cross bracings for

intermediate diaphragms

5 Click in Nodal Connectivity Click node at top and then move down diagonally to the bottom chord

6 Repeat for all intermediate diaphragms

4

4 Modeling - Intermediate Diaphragm

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7 Boundary > Rigid Links Create Rigid Link between top and bottom nodes

on the girder webs at intermediate diaphragms The top node as Master node and bottom node as Slave node

8 Click in Master node field and then click on top node in Model View window

9 Use Select Single to select the node directly below Master node as

Node/Element > Elements >Auto Mesh

1 Select Nodes

2 Type: Quadrilateral

3 Select Material 1

4 Select Thickness 1

5 Click the box to turn to green

6 Select nodes one by one in clockwise direction starting from left top

node to create an enclosed area (so the 1 st node and the last node should be the same)

7 When all nodes selected > Click Apply

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6

7

4 Modeling - Pier

1

A

1 Activate All Switch to Top-View Select by Window Select member corresponding to end diaphragm

over pier cap (Box A)

2 Click Activate(F2) and switch to Left-View

2

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2

3

Node A Girder bottom Nodes

1 Use Select Single and select the bottom nodes of the girders

2 Translate by (0,0,-12.4) Node/Element > Nodes>Translate

3 Select node A using select single, and translate through unequal distance along y axis by -36,-138,210,138

4 Modeling

1 Node/Element > Elements>Create Elements Set material as C5000

2 Create Pier Cap left end using Section as P_L ,click in nodal connectivity and click on nodes along a to c

3 Change Section to Pier Cap Center, click in nodal connectivity and then click nodes c to e

4 Change Section to P_R , click in nodal connectivity and then click on nodes e to g

1

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1 Properties>Tapered Section Group

2 Select by window the right end of pier cap

3 Enter name as P_Right

4 Z-Axis variation as Polynomial (2) with Symmetric plane

from J end

5 Y Axis variation being Linear

6 Click Add

7 Select by Window the left end of Pier Cap

8 Name as P_Left and Z axis symmetric plane from I-end

4 Modeling

1 Node/Element > Nodes>Translate Translate node a by (0,0,-72 in)

2 Using Select Single, select the translated node

3 Node/Element > Elements>Extrude Extrude Node into line element to create pier as shown in dialog box

Node a

Newly Translated node

1

1

2

3

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1 Boundary > Elastic Link

2 Select Rigid Type

3 Click in 2 Nodes field and then click at nodes a and b

4 Check on Copy Elastic link and copy along Y axis as shown

5 Click on nodes c and d

6 Boundary Conditions: Supports

Model > Boundary> Supports

1 Select the support nodes

2 Select Support type

3 Click Apply

Repeat for abutment nodes

2

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Load>Static Load Cases

1 Enter SW, SIDL as Dead Loads

4 Select the elements to be loaded For example,

for Girders, double click on girder section from Works Tree

5 Load>Element Beam Load Load case name as

SIDL

6 Enter element beam loads as UDL in z direction

-0.5 kips/ft (Change units from in to ft)

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1 Click on Groups tab under Tree menu

2 Right click on Structure group and click on New…

3 Enter name as Girder, click add

4 Enter name as Crossbeams + Diaphragms, click add, click close

5 Click on Select by Plane and select XY plane with Z=0 ft and click

Close

6 Click Activate

7 Double click on Girder under section in Works tree to select all girders

8 Go to groups tab, click on Girder under structure group and drag and

drop it over the Model View window (to assign the girder members

to the structure group.)

9 Right click on Girder structure group and select Inactive

10 Click on Select All and drag and drop the Crossbeam +

Diaphragm structure group on Model View window to assign the

diaphragms and crosbeams to the structure group

7 Loads: Live Loads (Define Lane)

Load > Moving >Moving Load Code

1 Select AASHTO LRFD from the moving load code

Load > Moving Load Analysis > Traffic Surface Lanes

1 Lane Name : Lane 1

2 Lane width: 12 ft

3 Wheel spacing:6ft

4 Offset: -7 ft

5 Selection by: Picking

6 Select all exterior nodes in bottom one by one starting from left bottom corner

7 Apply

8 Repeat the process for Lane 2 Only change Eccentricity to -23 ft

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Load > Moving Load Analysis Data> Moving

Load case

5 Enter a Load case name: MVL

6 Check or modify Multiple Presence Factor

7.Select loading effect for sub load case as

Independent

8 Add Sub-Load case

9 Select one of the vehicles

10 Scale factor as 1, and min number of loaded

lane as 1 and max as 2

11 Select lanes L1 and L2

1 Click Add Standard

2 Click on Vehicle load type

3 Select HL-93 TRK as first vehicle load

type., DLA = 33%,Click Apply

4 Select HL-93 TDM as second vehicle

load type Click OK

7 Loads: Moving Load analysis Control

Analysis> Moving Load Analysis Control Data

1 Set the analysis control as specified in the dialog box

1

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Load > Static Loads > Masses > Loads to masses

1 Select the Mass direction :X,Y,Z

2 Load type: Nodal, Beam, Floor, Pressure

3 Select the Load case (SIDL) to be converted and scale factor

4 Click Add

5 Click OK

Model> Structure type

6 Check on Convert Self Weight into Masses

8 Response Spectrum Analysis

1

2

3

4

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Load> Response Spectrum analysis data > Response spectrum load cases

1 Enter the Load case name RS-X

2 Select Direction and Excitation angle as 0 deg

3 Select Function name

4 Click Add And repeat with Load case name as RS-Y and Excitation angle as 90 deg

5 Click Eigenvalue Analysis Control

6.Select Lancoz Vectors as type of Analysis

7 Enter no of frequencies as 10

7

9 Perform analysis

Analysis > Perform Analysis