Week 9 Challenge

Aim : To calculate the wave load on the bridge superstructure by using following data.

Given data :

• Width of the deck slab is 9 m
• Span of bridge is 12 m
• Maximum crest elevation is 3 m
• I girder,

height is 1.7 m, width 2.5 m, thickness of eb and flange is 0.5 m

• Thickness of deck slab is 2 m
• R = 5 , C_va = 3, C_r = 0.4

Theory :

Waves are caused by disturbance of the water surface.

When the wind blows on the sea , waves occurs according to the intensity of the wind and generate a force on the any bridge sub structure like piers and abutments.

Calculation:

• Δ Z_h = η_max – centroid of girder

= 3 – ( 1.7 / 2 )

Δ Z_h = 2.15 m.

• Δ Z_v = η_max - elevation of bottom deck

= 3 – 2

Δ Z_v = 1 m

• Number of girder , N = 3
• Vertical load, F_v = r x Δ Z_v x A_v

= 5 x 1 x ( 9 x ( 1.7/2))

F_v = 38.25 KN

• Horizontal load, F_h = r x Δ Z_h x A_h

= 5 x 2.15 x ( 3.7 x 12))

F_h = 477.3 KN

• Max vertical load , F_{v max} = C_va x F_v

= 3 x 38.25

F_{v max} = 114.75 KN

• Max horizontal load , F_{h max} =[ 1 + C_r ( N – 1 ) ] C_va x F_h

= [ 1 + 0.4 ( 3 – 1 )] 3 x 477.3

F_{h max} = 1622.82 KN

Aim : To prepare the model in a STAAD Pro and perform the analysis and justify with the results.

Theory : The general steps to be create a STAAD Pro model is given below,

Step 1 : Create the nodes by using the nodes cursor.

Step 2 : Joining the nodes by using the respective beam plate cursor.

Step 3 : Supports given to the nodes whether its pinned or fixed or any other custom supports

Step 4 : specifications given to the respective beams plates

Step 5 : Assign the dead load as per calculation

Step 6 : Save the model and perform the analysis

Step 7 : The results are obtained and discuss with the results

Step 8: Take the print out of report of necessary results.

Creating the nodes by using node cursor.

Open the STAAD Pro window > Select > Node cursor > enter the value with respect to X Y Z axis > click enter

Join the nodes by using beam cursor.

Select > beam cursor > join by dragging the mouse or enter the node numbers > click enter

By using nodes and translation repeat plates mesh like structures are created.

Supports are given to the respective nodes.

Specifications > Supports > select the supports > click enter

Assigning the properties to the beam .

Specification > Prismatic > Rectangle > enter dimensions > select the beam > assign the properties to selected beams.

Plate thickness defined

Plate properties are defined.

Defining the load cases .

Loading > Load case detail > select load > Add

Add > nodal load X direction > enter value > ok

Add > nodal load Y direction > enter value > ok

Select the defined load > select the node > Assign to selected node > click enter

Select the defined load > select the node > Assign to selected node > click enter

Run analysis > go to post processing mode > Results

The reactions are generated at the end of the nodes .the reaction value is 6491.28 KN in X direction

• The maximum deflection in X direction is 5096.145mm
• The minimum deflection in X direction is 0 mm
• The maximum deflection in Y direction is 4932.89 mm
• The minimum deflection in Y direction is 4632.786 mm
• The maximum deflection in Z direction is 4632.786 mm
• The minimum deflection in Z direction is 4632.807mm

• The maximum shear force in X direction is 1565.364 KN
• The minimum shear force in X direction is -1756.681 KN
• The maximum shear force in Y direction is 1705.356 KN
• The minimum shear force in Y direction is -1527.338 KN
• The maximum shear force in Z direction is 312.177 KN
• The minimum shear force in Z direction is -343.617 KN

• The maximum bending moment in X direction is 1041.051 KN-m
• The minimum bending moment in X direction is -1169.141 KN-m
• The maximum bending moment in Y direction is 667.987 KN-m
• The minimum bending moment in Y direction is -665.402 KN-m
• The maximum bending moment in Z direction is 10206.491 KN-m
• The minimum bending moment in Z direction is - 10257.777 KN-m

• The maximum shear stress in y direction is 138.48 KN/m²
• The minimum shear stress in y direction is -143.241 KN/m²
• Reports are taken printout which ever is necessary by using report
• In the report option we obtain the results of section forces, displacement, reactions, plate
• The exact report is to be taken further move to design