Disadvantages of steel structures or Demerits of steel construction
Following are some of the disadvantages of steel structures.
- High maintenance cost and more corrosion
Most steels must be painted at regular intervals because if they are freely exposed to air they get corrode. This requires extra cost and special care. If we use weathering steel then this will eliminate this cost. If steel structures are not properly maintained then they can loose 1 to 1.5 mm of their thickness each year. As a result the structure will loose its weight up to 35% during its specified life span and can fail under external loads.
- Fireproofing costs
Although steel members are incombustible in nature, their strength is tremendously reduced at temperatures prevailing in fires. At about 400 degree Celsius, creep becomes much more pronounced. Creep is defined as the plastic deformation under a constant load for a long period of time. This produces large deflections in steel structures. Stresses will produce in main member forcing other members to higher stresses or even to collapse. Steel is an excellent conductor of heat. It may transfer heat from a burning compartment of a building to start fire in other parts of the building. Extra cost is required for properly fire proof of the building.
- Susceptibility to buckling
Steel sections usually consist of a combination of thin plates. The steel members dimensions are also smaller than reinforced concrete members. If these slender member are subjected to compression, there are greater chances of buckling.
Buckling is a type of collapse of the members due to sudden large bending caused by a critical compressive load.
Steel when used for columns is not very economical because considerable material has to be used to stiffen the columns against buckling.
- Higher initial cost / Less availability
In few countries, like pakistan, steel is not available in abundance and its initial cost is very high as compared with the other structural materials. That is the reason why steel structures are not very common in these countries.
For certain types of buildings, the steel structures are architecturally preferred. However, for majority of residential buildings and office buildings, steel structures are considered to have poor aesthetic appearance. At these places, they required false ceiling and cladding to improve their appearance. A good amount is required for such structures to improve their appearance.
Cladding is a covering of metal, concrete, plastic or timber to put on the surface of a structural member to completely encase it.
Reference : Steel structures by Zahid Ahmad siddiqi and Muhammad ashraf