Life-cycle cost analysis of bridge structures considering maintenance cost and seismic risk

Recently, Life-Cycle Cost (LCC) analysis has been paid attention as a possible and promising concept to achieve a rational maintenance program. In this study, an attempt is made to introduce the seismic risk into LCC analysis of bridge structures. Paying attention to some problems regarding the formulation of total expected cost minimization; it is intended to discuss the effects of seismic risk on LCC. In order to define a corrosion phenomenon of reinforcing bars due to chloride attack in terms of deterioration factors of reinforced concrete piers, the seismic risk is evaluated by reliability index in service time. In the calculation of LCC, maintenance cost and seismic risk are treated separately, because they have different accuracies in calculations. Namely, both of them are dealt with as objective functions in the LCC minimization. Thus, multiobjective optimization formulation is introduced, where Multi-Objective Genetic Algorithm (MOGA) is used to obtain several Pareto-solutions. Furthermore, LCC is calculated by introducing the user cost due to the occurrence of earthquake. Several numerical examples are presented to demonstrate the effectiveness of the proposed method.