Unified Reliability and Design Optimization in Earthquake Engineering

In this paper, a methodology is put forward that takes advantage of the emerging focus on structural damage in earthquake engineering. Contrary to the traditional focus on collapse limit-states in reliability analysis, a versatile “unified” limit-state formulation is employed. The methodology underscores the advantages of formulating explicit probabilistic models for the ground motion, structural response, damage, and ensuing losses. Next, by formulating limit-state functions in terms of total cost – including both the cost of construction and damage – a novel reliability-based design optimization procedure is put forward. By carrying out this design optimization in the tail of the total cost distribution; at unlikely but potentially devastating losses, an optimization strategy akin to the use of “risk averse” utility functions in classical decision analysis is achieved.