Week 12 Challenge

Aim :- To create truss bridge model and applying barge impact load on it and perform analysis using Staad.pro software.

* Manual calculation *

Given data :-

1. (W) The Dead weight tonnage of Panamax vessel is 52500 DWT.
2. (V) = 60 km /hr -- 16.67 m/sec.
3. (CH) =1.25.
4. (L) Span of the Bridge is 12m.
5. (B) Width of the bridge is 7m.
6. Piers of size 2.5 m x 2.5m.
7. The cross Girders size 0.75 m x 1.8 m.
8. The Deck slab is 500 mm thick.

Calculation of barge impact :-

Barge collision energy.

KE = 500 X CH X W X `(V)^2`

= 500 X 1.25 X 52500 X `(16.67)^2`

= [ 9118229531 ]

Barge damage depth 'aB'

ab = 3100 X [ (1 + 1.3 X `10^-7` X KE )0.5 - 1 ]

= 3100 X [ (1 + 1.3 X `10^-7` X 9118229531 )0.5 - 1]

= [ 103675.5316 mm ]

Barge Collision Impact force Pb

Pb = 6.0 X `10^6` + 1600 X (ab)

= 6.0 X `10^6` + 1600 X 103675.5316

= 171880850 N

= 171880 KN.

Uniform Force

= Pb / length of bridge

= 171880 / 12

= 14323 kN/m

* Analysis using Staad.pro software *

Step (1) :- Opening of Stadd.pro software

• Fill all inforation about model.
• Then click on create to open the model.

Step (2) :- Creating Truss bridge model.

• Create the first node using the cordinate.
• Now we need to create first cross beam of bridge
• For that select that first node using node cursor and copy it in Z direction upto 7 meter (Width of the bridge Given) using translational repeat option
• In translational repeat option select direction as Z and spacing should be 07 and also click link steps option to connect both the node then click on Ok to creat the cross beam.

• Lenght of the bridge is given 12 meter.
• So select that beam using beam cursor and copy it in X direction using translational repeat option.

• In translational repeat option select direction as X and spacing should be 2 meter and No of steps 6 nos.
• Also click on link steps to connect all the cross beam.

• Then Creating pier in model
• For creating pier fisrt select all four ending node of cross girder and copy them in Y direction using translational repeat option.

• In Translational repeat option select direction as Y and spacing should be -7 meter assumption (because we are copying node in inverse direction)
• No of step should be 1 and aslo select link steps option to connect both the node then click on OK to create.

• Creating vertical member.
• For that select both side node of middel cross beam and copy them in Y using translational repeat option upto 5 meter.

• In translational repeat option select direction as Y and spacing is 5 meter and also click on link steps to connect both the node than click on OK to create.
• Repeate same procedure for another cross beam .
• But put variation in spacing.

• After that connect all the node using add beam option.
• For that first go to geomertry in that select add beam option then connect all the node like wise shown in question.

• Creating deck slab for bridge.
• Select first node on crossbeam and copy them in X direction upto 0.5 meter using translational repeat option.
• Again select both the node and copy it in Z direction upto 0.5 meter using translational repeat option.
• After that adding plate to that node which we created for that go to geometry option in that select add plate option and connet all 4 node using this.
• Hence one plate is created.
• Then select that plate using plate cursor and copy it in X direction using translational reapeat option.
• 
• In teanslational repeat option select direction as X and spacing should be 0.5 Meter.
• And no of step is 23 nos, lenght of the bridge is 12 m so 12/0.5 = 24 , 24-1= 23 nos then click on OK to create.

• Againg select all the plate using plate cursor and copy them in Z direction using translational repeat option.
• 
• In above windown select direction as Z and spacing is 0.5.
• Width of bridge is given 7 meter so no of step should be 13 nos, 7/0.5=14, 14-1= 13 nos.

• Adding support to the piers.
• For adding support first go to specification then select fixed support option.
• Then one window will open in that window click on add option.
• After that suppot window will open.
• 
• In above window click on support 2 option and select all button node of all the piers and then click on assign button to add the support.
• Hence support is assign to all the piers.

Step (3) :- Assigning property to the structure.

• Adding property to the structure.
• For assigning proprty first go to specification then click on prismatic option then property window will open.

• Instert the value of piers as 2.5 X 2.5 M which is given in question then click on add option.
• After select all the pier using beam cursor and assign this proprty to it.

• Adding property to the crossgirder.
• Repeat same procedure as above.
• In property window put value of cossgirder as 0.75 X 1.8 metre as also mention in question.

• For main girder assume S shape property as ISMB 550

• For vertical component of bridge truss assume property as ISMB 500.

• For top chord and strut component of bridge assume property as ISMC 300

• For top lateral bracing assume angle property as IAS 90X90X10

• Adding propery to deckslab.
• For that go to specification then click on plate thickness after that plate property window will open.

• Assign 500 mm thickness of deckslab then click on add.
• Select the deckslab using plate cursor and assigned this property to it.

3D Model

Step (4) :- Assigning barge impact load to the structure.

• For assigning barge impact loading to the sturcture go to loading option.
• In right side of the window load & defination window will shown.

• In above window create load case 1 as barge impact load.
• 
• Select that load which we created and then click on add option.
• After that this window will open.

• In above window select member load in that select uniform force and insert that W1 as 14323.53 kN/m ( Barge Impact force) and also select direction as GY then click on add option.
• Then select that load and assign to the structure.

Step (5) :- Analysis of model.

• Go to analysis and design option than click on run analysis option.
• Then analysi process will start.
• 
• To view the result select post prossing mode in above window and click on done option.

Result :-

A) Bending moment diagram

B) Deflection diagram

C) Plate stress in MY and MX