Cost-effectiveness evaluation of an MR damper system based on a life-cycle cost concept

A method for evaluating the economic efficiency of a semi-active Magneto-Rheological (MR) damper system for cable-stayed bridges under earthquake loadings is described and its evaluation results are investigated in this paper. The economic efficiency of semi-active MR damper system is addressed by introducing the concept of life-cycle cost. We simply define the life-cycle cost as the sum of the initial construction cost and the expected cost of the damage over the lifespan of the structure. To evaluate the expected damage cost, the probability of failure is estimated by use of the crossing theory in conjunction with the simulation methods. As a measure of economic efficiency, the cost-effectiveness index is defined as the ratio of life-cycle costs between a bridge structure with the MR damper system and a bridge structure with shock transmission units. In order to examine the cost-effectiveness of the MR damper system, the scale of damage cost and the scale of damper cost are adopted as two parametric variables. The evaluation results show that the scale of damper cost has little influence on the cost-effectiveness of the MR damper system, while the scale of damage cost has a significant influence on its cost-effectiveness. It is also found that the MR damper system is highly cost-effective especially for the ground motion in regions of moderate seismicity with soft soil conditions and strong seismicity with stiff soil conditions.