Week 3 Challenge

Aim: 

To model and analyse by applying the IRS railway loads in Staad pro of an I girder bridge for the given specifications.

Given:

• Width of the bridge deck is 26 m, 
• Span of the bridge is 25 m,
• Pier size is 2.3 m in diameter,
• Pier height is 10 m in diameter.

Procedure:

Step 1: Open Stadd Pro connect edition software -> create a new file with the units set to metric standards.

Step 2: Select the geometry tab and enter the values of the node in the y column in the node table as 0 and 10 respectively which will create two nodes.

Step 3: Select add beam cursor and connect the two nodes creating a beam, this beam is one of the piers of the bridge.

Step 4: Select the beam cursor in the Select window -> Select the beam and Copy - paste the beam creating a new beam at a distance of 14.4m. Now, two piers are created. 

Step 5: Select both the beams using the beam cursor -> Select the translational repeat command from the geometry tab -> In the X direction for 1 step and spacing 25m create two more piers and also select link steps. Delete the linked beam connecting the bottom nodes.

Step 6: Connect the top of piers across the Z direction using Add beam command to create cross girders. Extend the cross girders for 5.375m from the sides and Select the cross girders using the beam cursor from the select tab -> Using translational repeat create cross girders across the X direction for one step for a spacing of 25 m. 

Step 7: Select the bottom left-most node using the node cursor (z=0 and y=0) -> Copy and paste that node in the x-direction for a spacing of 5m. Select the left-most and newly created node and copy and paste in the z-direction for a spacing of 3.714m.

Step 8: Select add plate command from the geometry tab and create a four-noded plate over the created four nodes.

Step 9: Select the plate using the plate cursor from the select tab -> Translational repeat the created plate over the X for 5 with a with 5 m and select all the generated plates and translational repeat them in Z direction for 6 steps with a 3.714 m spacing respectively.

Step 10: Specification tab -> Select fixed and create foundation -> Assign this fixed foundation to the four nodes under the pier.

Step 11: Pier - In the Properties tab -> select define -> circle -> 2.3m -> Assign -> close.

Step 12: Main Girder - In the Properties tab -> select define -> tapered -> F1=1.2m F2=0.5m F3=1.5m F4=0.5m F5=0.3m F6=0.5m F7=0.3m -> Assign -> close.

Step 13: Cross Girder - In the Properties tab -> select define -> rectangle-> YD=1m ZD=0.5m-> Assign -> close. 

Step 14: Deck - In the Properties tab -> select Thickness -> 0.35m -> Assign -> close.

Step 15: In the Materials tab -> Select concrete and assign to view.

Step 16: Select the Main girders using beam cursor from select tab -> In property tab -> assign the tapered for main girders.

Step 17: Select the Cross girders using beam cursor from select tab -> In property tab -> assign the rectangle for cross girders.

Step 18: Select the Deck slab plates using plate cursor from select tab -> In property tab -> assign the Thickness 0.35m for deck slab.

Step 19: Select the Pier beams using beam cursor from select tab -> In property tab -> assign the Circle 2.3m for Pier.

Step 20: In loading tab -> Defenitions -> Vehicle definition, click add -> Width= 1m, Electric train load details from IRC guidlines as 74.5kN - 0m, 74.5kN - 0.914m, 74.5kN - 0.914m, 74.5kN - 2.743m, 74.5kN - 0.914m, 74.5kN - 0.914m.

Step 21: In loading tab -> Load case details -> Generate a load type by clicking add -> primary -> enter electric train and click add.

Step 22: In loading tab -> Load case details -> Generate a load type by clicking add -> load generation -> click add -> Enter number of loads to be generated as 35 ( [[span of bridge + length of train] / increment length] ). Repeat once more.

Step 23: Click the generated load 1 -> add -> enter the co-ordinates as X=0,Y=0,Z=3.714 as the initial position and load increment in the X direction as 1 m. 

Step 24: Click the generated load 2 -> add -> enter the co-ordinates as X=0,Y=0,Z=14.856 as the initial position and load increment in the X direction as 1 m. 

Step 25: Save the file and Run the analysis by -> Click analysis and design tab -> click define commands -> no print, click add -> click run analysis and check for errors after computation.

Thus the structural analysis of the given data has been done and the results are interpreted below.

Results: 

The results can be obtained after analysis of the model and can be viewed in the post-processing tab under the workflow section.,

The train 1 load case is shown below from its origin point of iteration.,

 The train 2 load case is shown below from its origin point of iteration., 

The deflection of the Model can be seen below and the critical displacement is highlighted below., Critical Displacement = 32.217 mm.

The Reaction of the Model can be seen below.,

The Beam results of the Model can be seen below.,

Bending Moment in Z direction - Main girder., Critical Bending Moment = 585.254 kN/m

Bending Moment in Y direction - Main girder., Critical Bending Moment = 3.719 kN/m

Bending Moment in Z direction - Cross girder., Critical Bending Moment = 1379.407 kN/m

Bending Moment in Y direction - Cross girder., Critical Bending Moment = 55.847 kN/m

The Plate results of the Model can be seen below.,

Bending Moment in X direction, Critical Bending Moment = 38.192 kN-m/m

Bending Moment in Y direction, Critical Bending Moment = 35.006 kN-m/m

Shear Force in X direction, Critical Shear Force = 0.052 N/mm2

Shear Force in Y direction, Critical Shear Force = 0.039 N/mm2

These results are the representation of the critical deflection, reactions of supports, critical moment across X, Y, Z, and Axial load caused due to the live loads moving across the bridge's effective span of 25 m along X global direction.