Week 5 Challenge

Aim: 1.Calculate the design wind loads for the bridges to be designed at Mumbai.

2.Apply the wind load in Staad.pro

Given Data:

1. The height of the bridge above ground level is 9m
2. It is located in open terrain with well scattered obstructions of height less than 10m.
3. The pier size is 1.5 x 1.5 m.

Wind Load:

Wind load is the load, in pounds per square foot, placed on the exterior of a structure by wind. This will depend on:

• The angle at which the wind strikes the structure
• The shape of the structure (height, width, etc.)

Calculation of Wind Pressure:

Wind Speed (As per IS-875 2015 Cl6.3)

V_z= Vb K1 K2 K3 K4

V_z=Design Wind speed in m/s

Vb=Basic wind speed in m/s

Basic Wind Speed,Vb=44m/s(From IS 875 PART III 2015)for the region in Mumbai.

K1=Probalblility factor(Risk co-efficient)cl 6.3.1

Referring Table 1 of IS 875 PART III 2015, For important structure and wind speed 44m/s, the K1=1.07.

K2= Terrain roughness and height factor cl 6.3.2

As per Problems criteria this area coming under Terrain Category 2

Since, the bridge height is 9m and Terrain category 2, Factor K2=1.00

K3=Topography factor Cl6.3.3

As per Cl 6.3.3 IS 875 PART III 2015 for upward wind slope less than 3 Degree Factor, K3=1.00.

K4=Importance factor for the cyclonic region cl6.3.4

When the location is within 60km radius of the ocean, the cyclone factor is taken into account

K4 = 1.3

Design wind speed

Vz = Vb*K1*K2*K3*K4

= 44*1.07*1*1*1.3

= 61.204 m/s

Wind pressure

Pz = 0.6* Vz²

Pz = 0.6*61.204*61.204

= 2247.56 N/m2

Pz =2.248 kN/m2

Applying Wind load into Staad.pro

Creation of Single Concrete Pier and assigning 1.5m *1.5m properties

Using Translational repetition method Creating another three piers In Z-direction

Assigning 1.2m X 1.2m Cross Girders properties

Creating a Span Using Translational repetition method

Assigning 1.5m X 1.5m Main Girders properties

Creating slab Plates and assigning 0.5m thickness

Creating Fixed Supports

Checking complete Render View

Assigning Pier Group properties

Assigning Cross Girders ,Main Girders and Slab Properties

Assigning Wind loads

Defining wind Properties

Assigning wind definition to whole structure

Creating wind Load case details

Defining wind loads in X-Positive direction

Defining wind loads in X-Negative direction

Defining wind loads in Z-Positive direction

Defining wind loads in Z-Negative direction

Dispalying plates contour stresses(Max Absolute Values)

Displaying Axial Stresses