Earthquake Loss Estimation for Reinforced Concrete Buildings: Some Problems

Capacity spectrum procedures developed for the assessment and strengthening of existing buildings have become the basis of methods for estimating potential post-earthquake losses which are today widely used in the insurance industry, and for urban risk mitigation programmes. The areas to which these methods are applied often contain (or largely consist of) reinforced concrete apartment buildings which were built either before today’s “ductile” codes were introduced, or without benefit of them. However evidence from the performance of reinforced concrete structures in recent earthquakes indicates that failure very commonly occurs in a non-ductile manner which makes such calculated vulnerability approaches of questionable validity. On the other hand the alternative purely statistical approach to performance is unable to take account of many aspects of real building behaviour. The paper discusses the performance of reinforced concrete buildings in recent earthquakes and compares this with the assumptions of the calculated vulnerability models commonly in use.