Towards the Development of a Comprehensive Framework for Life Cycle Cost Analysis of Bridges Subjected to Multiple Hazards

Abstract

Life-cycle cost analysis (LCCA) is used as a decision-making tool in the design phase to predict the expenses required over the lifetime of the bridge. The application of LCCA to bridges allows to consider different types of uncertainties such as those on loads, resistances, degradation and on the numerical modelling and structural response analysis. In this context, the present paper proposes a general framework for bridges' LCCA under multiple hazards based on the use of the PEER equation. It allows to account for the random nature of hazards and for structural and modelling uncertainties, considering in a unified manner different hazards concurring to damage occurrence. The approach is for the first time applied to cost and fragility analysis of bridges subjected to fatigue, highlighting the possibility of treating the problem of fatigue damage estimation with an approach similar to the one currently adopted for damage induced by other hazards, like earthquake and wind. Starting from the knowledge of the traffic load model, the gross vehicles weight is assumed as intensity measure (IM) and a fatigue damage index calculated through the Palmgren-Miner's rule is adopted as engineering demand parameter (EDP). The damage accumulation is evaluated by considering the time dependency of the fatigue damage index. The framework is applied to the case study of a composite steel-reinforced concrete multi-span roadway bridge located in central Italy. The evolution over time of the probability of failure and the life-cycle costs due to fatigue damage induced by heavy traffic loads are investigated.