近断层地震作用下大跨CFST拱桥的动力稳定性

为研究大跨度CFST(钢管混凝土)拱桥在近断层地震作用下的动力稳定性能,以主跨132 m的下承式钢管混凝土拱桥为工程背景,以台湾集集地震记录作为横向输入,采用动态增量分析(IDA)方法,对动力失稳临界荷载的确定进行了探讨.为提高IDA的分析效率,采用了高性能数值计算并行处理方法.此外,还讨论了加强IDA曲线簇收敛的问题.结果表明:脉冲型近震可导致非线性极值动力失稳,失稳临界荷载明显降低；采用加权平均加速度峰值作为地震强度指标,能显著改善IDA曲线簇的离散性,有利于揭示近断层地震对钢管混凝土拱桥造成动力失稳的特点.

Dynamic Stability of Long-Span CFST Arch Bridge under Action of Near-Fault Ground Motions

In order to research the dynamic stability performances of long-span CFST(concrete-filled steel tubular) arch bridges under the action of near-fault ground motions,an arch bridge with a 132 m main span was taken as the engineering background,and seismic records of the Chi-Chi earthquake in Taiwan,China were set as transverse inputs.The incremental dynamic analysis(IDA) was adopted to determine the critical load of dynamic instability.To increase the efficiency of IDA,the parallel high-performance numerical computing was employed.In addition,the problem of strengthening IDA curve cluster convergence was discussed.The research result shows that near-fault pulse-like ground motions are likely to bring about a great damage and result in nonlinear dynamical limit-load instability,and the corresponding critical load is decreased evidently.Weighted average peak ground acceleration,an new intensity measure,can make the discreteness of IDA curve cluster be improved significantly to avail to reveal the dynamic instability characteristics of CFST arch bridges caused by near-fault ground motions.