Working Stress Method in RCC Design

Working stress method is a traditional method of designing reinforced concrete structures. In this method, the allowable stresses in concrete and steel are calculated based on their characteristics and properties. The working stresses are then compared with the actual stresses developed in the structure under load conditions. The factor of safety is applied to the allowable stresses to ensure the safety and stability of the structure.

Factors of Safety for Concrete and Mild Steel

In the working stress method, the factor of safety is used for both concrete and mild steel due to bending. The factor of safety is a multiplier that is used to reduce the allowable stress to a safe level. It takes into account the uncertainties in material properties, workmanship, and loading conditions.

For concrete, the factor of safety is usually taken as 3. This means that the allowable stress in concrete is divided by 3 to get the safe stress. The factor of safety of 3 is used because concrete is a brittle material and can fail suddenly without warning.

For mild steel, the factor of safety is usually taken as 1.8. This means that the allowable stress in mild steel is divided by 1.8 to get the safe stress. The factor of safety of 1.8 is used because mild steel has a yielding behavior and can undergo plastic deformation before failure.

Conclusion

In conclusion, the factors of safety used for concrete and mild steel due to bending in the working stress method of RCC design are 3 and 1.8, respectively. These factors of safety ensure the safety and stability of the structure under different loading conditions.

Answer ( A ) 3 and 1.8