Project 1

Calculate the dead load , IRS live loads , Earth pressure load , wind load and seismic loads for the bridge structure at Ahmedabad Metro rail project shown in the figure. Assume the unit weight of soil as 18 kN/m3 . Use IS 875 code book for finding the Basic wind speed at the site location. Use IS 1893 code book for determining the seismic zone. Assume suitable data.

Model the bridge structure in Staad Pro and Apply all the calculated loads

Data Given

Bridge has located Ahmedabad for Metro rail project

Sol:

Given data/Assumed data

1. Length of the Bridge = 120 m (5X24 m)
2. Height of Bridge= 12 m from founding level.
3. Foundation depth assumed 2 m from the ground level.
4. Pier Size 1.2 m dia circular
5. The Bridge is Located in open terrain with well scattered obstruction of height less than 10 m

The Dead Load has been Considered in the STAAD as below (factor is -1).

Foundation:

Pier

Rectangular raft foundation Size 16m X6 m X 1m

Bearing capacity assumed = 250 KN/m2

Allowable settlement =50mm =0.050 m

Modulus =250/0.05=5000 KN/M2/m

Supports are assigned as foundation with messing 0.5mX0.5 thickness of plate 1000 mm

Abutment

Length of the foundation= 16 m

Width of foundation = 8 m

Thickness of raft = 1 m

Supports are assigned as foundation with messing 0.5mX0.5 thickness of plate 1000 mm

Messing 0.5mX0.5m with help of transilation repeat for raft foundation required dimensions for both Abutment and pier also.And after create the required dimention copy and paste command with help of reference pont as below

Beam also created with help of connecting node as required and messing 0.5mX0.5m for the deck slab thick 250 mm below

Three-dimension view of the total bridge model as below with both abutment wall and return wall with plate model thickness of 1 m

Live Load:

Live load has considerd IRS Metro loading

Metro Vehicle width 1.435 m

Axel Load 170 KN

170 KN

170 KN 2.2 m

170 KN 12.4 m

170 KN 2.2 m

The Vehicle defination as shown below

Load generation has created as below

No of Load generation =Vehicle length+Length of the Bridge/Increament length

= (16.8+120)/1 =136 Nos.

Earth Pressure:

Calculation of Earth pressure Load

Density of the Soil (Ὕ )=18 KN/M2

Height of the Wall =12 m

Foundation depth 2 m from the GL

Earth pressure on abutment = ὝXD1

D1 depth of the Foundation from Abutment Top=12 m

D2 Depth of foundation from the Ground Level= 2 m

EP1=18X12=216 KN/m2

The Earth Pressure acting on Abutment wall A1 and A2 has applied as hydrostatic pressure on plate elements in +X and -X direction respectively in the STAAD Model as show above

The Earth pressure acting on the plate elements of Return walls as hydrostaic pressure in +Z and -Z directions as shown below

Calculation of Wind Load

As per IS 875 part -3 2015 clause No 6.3 Design wind speed is mathematically expressed as below

Vz = Vb X k1 X k2 X k3 X k4

Where Vz = Design wind speed at height z, in m/s

Vb Basic wind Speed of Ahmedabad = 39 m/s as wind map.

K1= Probability factor risk coefficient (clause 6.3.1 Table-1) = 1.06 (Important building and structures)

K2 = Terrain roughness and height factor category 2 (clause 6.3.2 Table-2) =

For 10 m -1.00

15 m- 1.05

12 m K2=1.02

K3 = Topography factor (clause 6.3.3.1) up wind slope assumed as below 3 degrees

= 1.00

K4 = Importance factor for the cyclonic reason (clause 6.3.4) which shall be considered within 60 KM radius from costal area (Mumbai is in that region)

The Bridge can be considered structures of post cyclone for emergency services

= 1.3

Design wind speed (Vz) = Vb x k1xk2xk3xk4

= 39X1.06X1.02X1X1.3 = 54.81 m/sec

As per IS 875 part-3 clause 7.2 the Design wind pressure is Pz

Pz=0.6 VzXVz

= 0.6 X 54.81 X 54.81= 1802.48 N/m 2

= 1.802 KN/m 2

• Wind Load on the columns in Z direction

Column size is 1.2 m dia (as per data given).

Member Load = 1.802X1.88=3.38 KN/m

• Wind Load on Cross Beam in X direction

Beam Size is 0.9 mX1.2 m

Member Load is 1.802X1.2= 2.162 KN/m

• Wind Load in Z direction.

Load on Main beam (0.9 mX1.2m)

Load on Main beam is 1.802X1.2= 2.162 KN/m

The Wind Load applied on the End main beams and colums in -Z direction in the STAAD Model as shown below

Seismic Load as per IS 1893

Ahemedabad is fall under Seismic Zone-3

Considered parameters for seimic Zone-3 as per IS-1893(part-1)-2016

Zone factor-0.16

Impotance factor =1.15

Rock and soil site factor =2

Type of structure= 1

Damping ratio =0.05

Response reduction factor =2.5

The Seismic load has applied in Z direction as shown below

The Seismic load has applied in X direction as shown below

Sorry I have done mistake again for EQ loads so The program is sucessful