Resilience-based multi-objective optimization for determining the optimal sequence of bridge retrofit projects

Abstract

This study intends to provide a methodology for determination of the optimal sequence of bridge retrofit projects in the pre-disaster phase. A two-stage optimization model is proposed. In the first stage, single-objective optimization is used, and the weighted average number of reliable independent pathways (WIPW) is adopted as the measure of network resilience (MOR) to be maximized. In the second stage, multi-objective optimization is used, and two objective functions are introduced to be maximized: the measure of strategy implementation sequence (MOS) and the measure of strategy implementation time (MOT). The proposed methodology is illustrated using a hypothetical community road system. The results show that there is an inverse relationship between MOS and MOT. By considering these two new objectives in the process of pre-disaster risk mitigation planning, network owners can determine the trade-off between MOS and MOT and select a proper sequence of bridge retrofit projects based on predictability of the examined disruptive events.