Working stress design or Limit state design?« Back to Questions List

Limit state design is better as it gives you economical section for structural members.

Working stress considers material strength only upto elastic limit whereas limit state considers the material strength upto ultimate value. so it gives economical results

deflection control requires working stress method better than limit state
yet, limit state saves quantity of material
but fire resistance on meterials suggest working strength is better
working strength is safer but lesser economical
now Euro code has removed all such resrictions
refer to Euro codes for better understanding

General theory of WSD method is reducing the capacity of material. For example, in WSD method compressive capacity of concrete is considered as f’c=0.6*fc, but in USD method we consider the full capacity but a safety factor is always used in the equation.for example, f’u= fi * fc

General theory of WSD method is reduce the capacity of material. For example, in WSD method compressive capacity of conrete is considered as f’c=0.6*fc, but in USD method we cinsider the full capacity but a safety factor is always used in the equation.for example, f’u= fi * fc