IMPROVEMENT OF SEISMIC CONTROL OF CABLE - STAYED BRIDGE USING SIMULTANEOUS ANALYSIS OF COST AND LOSS

In cable-stayed bridges, passive seismic control is usually performed by using bearingdevices in the place where deck and pylons connect to each other. However, owners usually refuse to use more expensive bearing devices despite their superior seismic behavior.In Mashhad cable-stayed bridge as a case study located in Iran, Pot Bearing device has been used which is not very effective in seismic behavior. While, Elastomeric Bearing Pads or Lead Rubber Bearings are more effective in absorbing earthquakeʹs energy due to higher damping. Thus, the use of Pot Bearing was probably because of the lower costs compared to Lead Rubber Bearing.So in this paper, we are going to thoroughly compare the use of different bearingdevices in Mashhad bridge using simultaneous analysis of the construction costs and losses due to earthquake.Indeed, if economically justified, this paper tries to improve the passive seismic control device of the Mashhad bridge from its current Pot Bearing to another type. The economic justification is studied using seismic risk assessment process alongside simultaneous analysis of costs and losses. To achieve this purpose, it is necessary to design and control the bridge for seismic behavior with three aforementioned different bearing devices. Then, the seismic risk assessment process is performed for each cases. The final results of seismic risk assessment process are achieved as Total Loss Ratio curves. Then, the proposed Cost-Loss-Benefit (CLB) method will compare the three cases by defining Benefit Ratio (BR) as a profitability measure. The final results indicatethat both of the alternative cases increase the costs and decrease the losses compared to the existing Pot Bearings. However, simultaneously considering the costs and losses, the BR coefficient reveals the profitability of the use of Lead Rubber Bearings in Mashhad cable-stayed bridge.