Week 7 Challenge
Aim: To calculate the water current forces of the bridge and apply in the staad pro. and perform structural analysis.
Given:
Span of the bridge = 45m
Mean velocity of the river = 3m/s
High flood level = 2m above the foundation level
Diameter of the pier = 1m
Height of the pier = 3.965m
Thickness of the foundation plate 0.765
Theory:
Whenever bridge piers are subjected to flowing water conditions or running water in the river, they are subjected to a force called water current force.
Water current force as per IRC
F = 52*K*V^2*A
Where,
P = Intensity of pressure due to water current in kg/m2
V = maximum velocity of the current at the point where the pressure intensity is being calculation in m/s
K = constant based on the shape of piers
A = surface area of pier m2
Calculation:
Mean velocity of river = 3m/s
Water current force as per IRC
F = 52*K*V^2*A (circular pier K = 0.66)
= 52*0.66*3.9^2*(π*0.5*2)
=1640 kg
=16.08kN
UDL apply in pier = F/L
= 16.08/2
= 8.04kN/m
Insert two nodes for coordinate of (0,0,0) and (45,0,0)
Translational repeat in X direction spacing 2m no. of steps 3 and link all nodes. 
Add beam to joining all nodes for deck slab.
Translational repeat in Y direction spacing- 3.965m no. of step one
Add beam to joining nodes for piers
Translational repeat in X direction spacing 0.5m no. of step one.
Translational repeat in Z direction spacing 0.5m no. of step one.
Add plate to joining of all four nodes.
Translational repeat in X direction spacing 0.5m no. of steps 89 for deck slab.
Translational repeat in Z direction spacing 0.5m no. of steps 11 for deck slab.
Add mate plate in bottom of the foundation.
Section details pier of the bridge circular pier are use with 1m dia.
Section details main girder of the bridge I section with steel material.
Section details cross girder of the bridge rectangular section with steel material.
Section details deck slab of the bridge with thickness of the plate 0.3m
Section details mate plate of the foundation with thickness 0.765m
Go to load cases details and add Water current load case 1
Add trapezoidal load in global Z direction W1 8.04kN/m and w2 0kN/m with d1 1.965m and d2 3.965m respectively.
Go to load cases details and add Water current load case 2
Add trapezoidal load in global Z direction W1 -8.04kN/m and w2 -0kN/m with d1 1.965m and d2 3.965m respectively.
Go to load cases details and add dead load case 3
Apply self-weight of the structure in Y direction factor -1
fixed support of the plate mate with modulus of 12500kn/m2/m
Go to run analysis and run this file.
Result:
Reaction
Displacement
Beam:
Maximum shear force in X Direction is 1043.222kN for beam no. 1382 respectively load case no. 3 dead load.
Minimum shear force in X Direction is -1.771kN for beam no. 18 respectively load case no. 2 water current load.
Maximum shear force in Y Direction is 1119.224kN for beam no. 16 respectively load case no. 3 dead load.
Minimum shear force in Y Direction is -1119.936kN for beam no. 12 respectively load case no. 3 dead load.
Maximum and minimum shear force in Z Direction is 55.408kN and -55.408kN for beam no. 14 and 11 respectively load case no. 3 dead load.
Maximum and minimum bending in X Direction is 224.490kip-in and -224.491kip-in for beam no. 1 and 1202 respectively load case no. 3 dead load.
Maximum and minimum bending in Y Direction is 1057.447kip-in and -1057.442kip-in for beam no. 14 and 11 respectively load case no. 3 dead load.
Maximum and minimum bending in Z Direction is 37508.734kip-in and -41271.899kip-in for beam no. 8 and 108 respectively load case no. 3 dead load.
Plate:
Maximum and minimum plate bending in X direction is 25.197kip-in/in and -40.520kip-in/in for plate no. 1687 and 1617 respectively load case no 3 dead load.
Maximum and minimum plate bending in Y direction is 21.045kip-in/in and -64.4773kip-in/in for plate no. 1663 and 1617 respectively load case no 3 dead load.
3D view:
