Every Building has its own defined loading and they are designed differently. All building are designed for some pre design loads due to construction materials, loads due to people, furniture and loads due to natural disasters like earthquake and wind etc. Placement of heavy building materials, machineries, etc. at the time of construction or additional loads during the service life of the building causes the overloading. Overloading leads to the more than permissible stresses in RCC member or imposes the excessive load on the subsoil, which ultimately may become a reason for building collapse.
The overloading may cause building collapse; it can happen during the construction stage or after construction. I.e. during the service life of building.
Courtesy - Nationalgeographic
How the Building Collapse due to Overloading?
Buildings are mostly designed for the normally expected loads expected during its life time, but sometimes building is overloaded then the designed load.
The overloading may happen during the construction stage due to following reasons:
- The negligence of the workers during the construction stage (storing of the excessive amount of building materials like cement, sand, bricks, steel bars, etc. at one place on the floor of the building).
- The heavy machinerieslike the crane, hoist, etc. are placed on the floor for lifting the building materials.
In such cases, if the load is excessive then it will affect the stability of the building and building may collapse partially or totally.
Normally building should not be subjected to more load than design. If the building is subjected to any load which is more than the designed one, it is likely to fail either immediately or over a period of time.
The building should be properly restrained and braced before the overloads are applied. The amount of loads, the duration that the load applied, and the placement of load should be managed for the safety of the building at the time of construction. It is advisable to concern the structural engineer before storing of heavy materials or machineries at one place in the building.
The overloading may also happen after the construction i.e. during the use of the building.
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Following are the reasons for building collapse due to overloading:
- Adding additional floor over existing building (floor for which structure is not designed)
- Placing of water tank at a place, which is not designed for such load.
- Using an ordinary room as a godown of heavy materials like grains, potatoes, books etc.
- Converting the ordinary room for purposes like store, library, etc. where loads are heavy.
- The building is designed for the residential purpose, and it is used for the commercial or institutional/industrial purpose including machineries with heavy vibrations.
- Cantilever balcony/projection done subsequently without adequate provision in design. Converting cantilever balcony into any type of room also may leads to the partial collapse of building.
This excessive load causes excessive stresses in the different structural elements of the building and may invite building collapse either partially or totally.
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