Seismic optimization of high-speed railway bridges considering the running safety of trains in normal service

Abstract

This article proposes a seismic optimization strategy to reduce the cost of piers of simply-supported bridges for high-speed railway (HSR) in China. The dimension and reinforcement ratio of piers are defined as variables. The running safety of high-speed trains during normal operation is considered by novelly setting the vibration amplitude of running trains to satisfy the corresponding constraint condition. Other constraint conditions include the structural fundamental frequency, buckling stability, and longitudinal stiffness, as well as the stress and crack width of piers during earthquakes. An improved genetic algorithm with a double-filter strategy is proposed to increase the efficiency of the optimization calculation. Six HSR simply-supported bridges with different pier heights are selected as examples to verify the effectiveness and applicability of the proposed optimization method. The result shows that for the example bridges, the cost of the optimised piers that are not higher than 30 m can be reduced by 33.38% to 50.65%. The optimised piers can ensure the integrity of the HSR bridges subjected to the considered earthquakes and can provide sufficient stiffness to ensure the running safety and stationarity of high-speed trains.