Week 1 Challenge

1.What are different type of foundation in bridges and how selection of type is made.

Ans. Different types of foundation in bridges are as follows

• Shallow foundation - (d<=b)Depth of foundation is less than or equal to breadth of foundation
• Deep foundation - (d>b)Depth of foundation is greater than breadth of foundation

  Shallow foundation	Deep foundation
  Combined Mat/Raft Spread or isolated	Pile foundation
  Strip Strap or Cantilever	Well foundation

factors for selecting for deep foundations:

• Poor bearing capacity of the soil at upper strata on the site.
• Liquefaction of soil strata.
• Large fluctuations in subsoil water level.
• Presence of canal or deep drainage lines near the foundation due to which width of foundation is restricted.
• Structure near seashore or riverbed.

2.Name all the components of a RCC girder bridge resting on open foundation. what additional effects it will create if we have a) seismic case 5, b)3 span continuous bridge Position all the loads on the bridge having 12 m and 7.5 m carriageway transverse width with to the scale drawings. Also mention all the clauses of IRC 6

Ans-: Components of a RCC girder bridge resting on open foundation are as follows:

1. Hand Rail
2. Deck slab
3. RCC girder
4. Bearing
5. Pier cap
6. Pier
7. Foundation

clauses of IRC 6

CL-203 Dead Load , 204 Live Loads, 209 Wind Load, 213 Buoyancy, 214 Earth Pressure, 215 Temperature

3.What are the various forces acting on the shallow foundations. how they will be different in the case free pier, fix pier and abutment. Show a diagram and loads acting on it.

Ans-:various forces acting on the shallow foundations

Dead Load , Live Loads , Super imposed dead load, Wind Load, Horizontal Forces due to Water Currents
Longitudinal Forces (Braking), Buoyancy, Earth Pressure , Temperature Load

Note: wind load, horizontal, water current act on fixed pier not in free pier