The commentary to ASCE 7 quantifies the intended performance for buildings in different Risk Categories. Below Table summarizes the anticipated reliability values. These values have not been validated with experience or in-depth analysis, but instead are notional values that represent the intent of 48 the building code committee. FEMA P-695 (2009) also suggests that the probability of collapse due to MCER ground motions should be limited to 10% for Risk Category II buildings. FEMA P-695 presents a detailed methodology for determining collapse probability of classes of buildings. Several case studies have used the methodology to benchmark performance of modern buildings, with results reported in FEMA P-695 (2009) and NIST (2010).
Risk Category | Probability of Total or Partial Collapse ( % ) | Probability of Failure that could result in endangerment of individual lives ( % ) |
|---|---|---|
I & II | 10 | 25 |
III | 6 | 15 |
IV | 2.5 | 10 |
Firstly, ASCE 7-16, the earthquake design values for most locations in the United States have been adjusted so that structures having standard collapse fragility will have a collapse probability of 1% in 50 years.
According to ASCE 7-16, target reliability values for structural stability caused bu earthquake due to MCER earthquake ground motion is given below.
Risk Category | Conditional Probability of Failure ( % ) | Conditional Probability of Component or Anchorage Failure ( % ) |
|---|---|---|
I & II | 10 | 25 |
III | 5 | 15 |
IV | 2.5 | 9 |