Life Quality Index for Optimizing a Safety Improvement Program

Abstract

The Life Quality Index (LQI), a composite social indicator, was proposed as a basis for evaluating the effectiveness of investments in safety measures to enhance life quality. In the structural reliability field, the life cycle cost (LCC) minimization method is widely used to optimize the structural safety and LQI has often been considered to provide a lower bound to the target safety. This study presents a systematic formulation of an LQI-based approach to optimize structural safety and demonstrates that the LCC minimization that excludes life safety considerations is a subset of the LQI optimization problem. This unified approach shows that a consideration of the life safety objective is the dominant criterion for optimization in contrast to the minimization of the LCC function alone. In other words, the LQI approach demonstrably leads to a higher level of target reliability than that obtained from the LCC approach.