Question

According to the concept of Limit State Design as per IS 456: 2000, the probability of failure of a structure is _____________.

Answer 1

According to IS 456 : 2000

Limit state method concept:

1) In this concept, the structure shall be designed to withstand safely all loads liable to act on it throughout its life, it shall also satisfy the serviceability requirements, such as limitations on deflection and cracking.

2) The acceptable limit for the safety and serviciability requirements before failure occurs is called a limit state.

According to clause 6.1.1

The characteristic strength is defined as the strength of material below which not more than 5 percent of the test results are expected to fall.

∴ Chances of no failure = 100 – 5 = 95 % = 0.095

∴ Probability of failure = [1 – P²] = [1 – (0.95)²] = 0.0975