The types of loads acting on structures for buildings
- Dead load
- Live load
- Wind load
- Earthquake load
Dead load (D.L)
It is defined as the force whose magnitude, positions and direction remain constant. It is the load of the materials used in the construction of the building i.e. self-weight of different compounds of the building like the floor, walls, plaster, doors, windows, beams, columns, slabs etc. A dead load of any such part is calculated by multiplying its volume by unit weight of the material. The unit weight of the material. The unit weight of common material used in building construction is given in I.S – 875, 1967
| Building Material | Unit Weight(KN/m3) |
|---|---|
| Stone | 20 to 28 |
| Bricks | 20 to 24 |
| Steel | 78 |
| Plain Cement – concrete | 22 |
Live load
It is the movable superimposed load acting on the structure. It comprises of the weight of occupants, furniture, equipment, machinery etc. it is considered to be uniformly distributed load acting on the area. The minimum live load to be for design depends upon the type of building as shown in the table. Their maximum magnitude, worst position, and direction should be taken into account. I.S 875-1964 gives minimum live load per square meter of the floor area as equivalent static uniformly distributed loads.
| Types of floor | Minimum live load (KN/m) |
|---|---|
| residential building, hospital | 2.00 |
| office room, small workspace | 2.50 |
| Steel | 78 |
| bank and reading room | 3.00 |
| classrooms, assembly halls for lightweight | 4.00 |
For multistoried building, while designing columns, wall and foundation, full load on each floor is not considered and reduction in live load is considered, as all floors are not likely to be simultaneously loaded. The live load for upper floor is reduced by applying reduction factors as shown in the table.
| No. of floors | Reduction in live load |
|---|---|
| First floor | No reduction |
| Second floor | 10% |
| Third floor | 20% |
| Fourth floor | 30% |
| Fifth floor | 40% |
Wind load
Wind load is effective in case of tall building. When the wind is obstructed by the structure is exerts a pressure it exerts a pressure on a structure known as wind pressure.
Earthquake load
The effect of the earthquake is taken equivalent to imparting acceleration to the foundation in the direction in which the wave is traveling.