Limit State of Serviceability in IS-456

The Limit State of Serviceability is one of the two limit states that are considered in the design of reinforced concrete structures as per IS - 456. This limit state deals with the serviceability requirements of the structure, which include the comfort and safety of the occupants, as well as the functionality of the structure.

Serviceability Limit State Criteria

The following criteria are considered for the serviceability limit state:

1. Deflection: The deflection of the structure should be within the permissible limits to ensure the safety and comfort of the occupants.

2. Cracking: The formation of cracks in the structure should be limited to avoid the entry of moisture and harmful gases.

3. Vibration: The vibration of the structure should be limited to ensure the comfort of the occupants and the proper functioning of the equipment.

4. Durability: The durability of the structure should be ensured by protecting it from environmental factors like corrosion and chemical attack.

Limit State of Serviceability for Floor Vibration

Floor vibration is a significant concern in the design of structures, especially for floors that are subjected to dynamic loads like foot traffic, machinery, and wind. The Limit State of Serviceability addresses this concern by limiting the amplitude of vibration of the floor.

The permissible amplitude of vibration is determined by the type of occupancy and the frequency of the load. For example, the permissible amplitude of vibration for office buildings is lower than that for warehouses, and the permissible amplitude of vibration for a load with a frequency of 10 Hz is lower than that for a load with a frequency of 1 Hz.

Conclusion

In conclusion, the Limit State of Serviceability is an essential aspect of the design of reinforced concrete structures that ensures the safety, comfort, and functionality of the structure. Floor vibration is one of the criteria considered under this limit state, and the permissible amplitude of vibration is determined by the type of occupancy and the frequency of the load.