Challenge

Week 7 Challenge

NNikhil Agnihotri8 Dec 2022

Aim of The Challenge : To Model & Analyse the Bridge Section which is having 2n span of 45.0m length for water Current Forces acting on the bridge having Highest Flood Level (HFL) 2m above the Foundation Level also the river stream is having a mean velocity of 3 m/s, in Staad Pro and Brielfy Identify The Displacement, Bending Moments & Shear Forces Developed on the Structure while subjecting to Water Current Forces.

Introduction : As we Know Staad Pro is Designed and Maintained by Bentley Systems Software Company, Staad Pro is used for Structural Analysis and Design Purposes, As the Given Structure is a Bridge of 45m span, we have to analyse the structure for Water Current Forces and briefly describe the analysis results.

Procedure :

Calculations :

V is Maximum Velocity of current at the point where the pressure intensity is being calculated

V = (√2) x Mean Velocity

V = (√2) x 3 = 4.242 m/s

According to IS Code 78-2000 Section VII table No 4 Page No 21 is value of K is 0.66 for Circular Piers

k = 0.66 for circular piers

Water Current Forces = P = 52 x k x V^2

P = 52 x 0.66 x (4.242)^2

P = 617.573 Kn / M^2.

Modeling :

1. Open Staad Pro and Create a new Project and select Metric in Unit, this will allow us to model the structure in metres as shown in the given diagram and get results in Kn.
2. Input the origin node as 0,0,0 Select the node press CTRL C+ CTRL V input -10 in Y and press ok, create beam between two nodes now select and select both the node and beam and perform translational repeat number of steps 2 and distance is 8 in Z direction, select all the beams and perform translational repeat number of steps 2 and distance is 45 Click Link Steps in X direction, now connect the top girders with the beam.
3. Now we can have to Provide Supports in Pier Bottom Select all the bottom Nodes Click on Specification in Upper Tab Create a Fixed Support and Assign the Bottom Nodes to Fixed end Support.

Assingning Specifications :

1. Click on Specification Tab click on Define click on Circle Add a Pier Size of 2.0 m Click Add, Again Click on Define Click on Rectange Assign the Cross Girders as YD - 2.5, ZD - 0.3 m. Again Click on Define Click on Taper I Assign the Longitudinal Girders as shown in the image below.

2. Select all the Piers and Assign the Specification having 2.0 m Configuration, Similarly Click on Select click on Parallel under Beams click on parallel to X Which selects all the Vertical Girders and Assign the Specification having Taper I Section Configuration, Similarly Click on Select click on Parallel under Beams click on parallel to Z Which selects all the Cross Girders and Assign the Specification having YD - 2.5, ZD - 0.3 m Configuration, After assigning all the properties the model should look like the image provided below.

Adding Water Current Loadings:

1. Click on Load Cases Details Click add Write Name Water Current Forces I, again click on Water Current Forces I click add under Member Load click on Trapazoidal and give properties as given in the image below.

2. Click on Load Cases Details Click add Write Name Water Current Forces II, again click on Water Current Forces II click add under Member Load click on Trapazoidal and give properties as given in the image below.