Week 9 Challenge

Aim :- Calculate the wave load on the bridge superstructure and perform analysis using STAAD.pro software.

Manuall Calculation,

Given,

1. The maximum crest elevation for the wave = 3 M
2. Storm elevation = 8.5 M
3. I girder size, * Height = 1.7 M * Flange width = 2.5 M * Thickness = 0.5 M
4. Span of the bridge = 12 M
5. Width of deck slab = 9 M
6. Thickness of deck slab = 2 M
7. Constant r = 5
8. Cva = 3
9. Cr = 0.4

Calculation,

Vertical Force Horizontal Force

Fv = `gamma` x (`Delta`Zv) X Av Fh = `gamma` X (`Delta`Zh) X Ah

= 10 X 2.8 X 108 = 10 X 1.9 x 26.4

= 3024 kN = 501.6 kN

`**`(Fv)max = Cva-v Fv

= 3 X 3024

= 9072 kN

Vertical Wave Load = (Fv) max / Av

= 9072 / 108

= 84 kN

`**`(Fh)max = [1+Cr(N-1)]Cva-h Ah

= [1+0.4(3-1)]x3x501.6

= 2708.64 kN

Horizontal Wave Load = (Fh)max / Ah

= 2708.64 / 24

= 112.68 kN

Analysis using STAAD.pro software,

Step (1) :- Open a STAAD.pro Software.

• Open STAAD.pro software and Fill model information regarding structure.
• Then Click on create to open a model.

Step (2) :- Create Girder in model.

• Create first node using cordinate.
• Then Select that node and copy it in X direction using Translational repet option upto 12 meter.
• Connect both the node using Add beam option i.e one girder is created.
• Then select that girder and copy them in Z direction using translational repeat option.
• 
• In translational repeat option, No of step = 2 and spacing should be 4.5 meter then click on Ok to copy.
• Hence all gider is created.

Step (3) :- Creating Crossbeam in model.

• For creating crossbeam first go to geometry in that select add beam option.
• Then connect all the node which is parallel to Z direction by using add beam option.
• Hence crossbeam is created.

Step (4) :- Creating piers

• First we need to insert node in center of crossbeam to make a pier.
• For that go to geometry option then select insert node in beam menu after that courser will change.
• Select any crossbeam by using this cursor then this window will open.
• 
• In this window select add mid point then click on ok button, then node will be inserted at mid point of the crossbeam.
• Repeat this same procedure for remaing crossbeam.
• After that select all the node which we created, copy them in Y direction using translational repeat option.
• 
• Select global direction as Y and No of steps is 1 , and spacing should be -7 meter ( :. height of pier is given in que is 7 meter and ' - ' sign for inverse direction) also select link steps option to connect all the node.
• After that click on Ok to create a piers.

Step (5) :- Creating deckslab in model.

• Select the first node.
• 
• Then Copy it in X direction upto 0.5 metre using translational repeat option.
• Again select both the node and copy them in Z direction upto 0.5 meter using translational repeat option.
• Adding plate to created node for that go to geometry then select add plate option.
• And connect all four node using add plate option (:. one plate is created).
• After that select that plate using plate cursor and copy them in X direction using translational repeat option.
• 
• In translational repeat Select global direction as X and spacing should be 0.5 meter.
• No of should be 23 (:. 12/0.5= 24, 24-1 = '23') click on ok to create.
• Again select all the plate which is parallel to X direction and copy them in Z direction using translational repeat option.
• 
• Select direction as Z and spacing is 0.5 meter.
• No of steps is 17 (:. 9/0.5= 18, 18-1= '17') click on ok to create.
• Hence deckslab is created.

Step (6) :- Assigning support to the piers.

• For that go to specification then click on fixed support option.
• Create support window will open in this window also click on add button.
• Then support - whole structure window will shown.
• 
• In above window click on support 2 option then select buttom node of all the piers.
• Then select assign to selected nodes and then click on assign button.
• Support will be generated under all the piers.

Step (7) :- Adding property to the piers.

• Go to specification then click on prismatic option then property window will open.
• 
• In above window select circle then fill YD as 1.2 meter dia of circle (Assumption) then click on add option.
• After that select all the piers using beam cursor and assign this property to it.

Step (8) :- Adding property to the girder.

• Go to specification then click on prismatic option then property window will open.
• 
• In above window select Tapered I section and insert the size of girder which is given in question then click on ok.
• After that select the all the girder and assign this property to it.

Step (9) :- Adding property to the crossbeam.

• Repeat same procedure as mention in step 8
• In property window select rectangle and assume size of crossbeam as YD as 1.7 and ZD as 0.75 meter.
• 
• Property is assign to crossbeam.

Step (10) :- Adding thickness to deckslab.

• Go to specification then click on plate thickness then plate element property window will open.
• 
• Put 2 meter value of plate thickness as given in question and then click on add button.
• Then select all the deckslab plate using plate cursor option and assign this plate thickness property to it.

(3D Model)

Step (11) :- Assigning wave load on structure.

• First go to loading menu then in right side of the window this window will shown.
• 
• In above window select load cases detail then click on add and then create one load case as 'wave load'.
• Then select that load case which we created again click on add button after that Add new: Load item window will open.
• In above window click on nodal load then select node option.
• After that put value of Fz as 112.68 kN in above window then click on add.
• After that again put value of Fy as 84 kN in that window, all value we calculated above mannually.
• Two load will be geneated.
• Then select Fz load and assign it to the selected node.
• 
• Again select the second load Fy and assign to the center node of the bridge.
• 
• Hence all loads is assigned.

Step (12) :- Analysis of structure.

• First go to analysis and design menu in that click on run analysis option.
• Then analyis process will start.
• After process is over this window will open.
• 
• In above window select post processing mode option and then click on done button to view the result.

Results:-

A) Bending moment result.

B) Plate result Mx And MY.