大跨度斜拉桥时程分析输入地震波峰值调整方法

Peak adjustment method of input seismic wave in time history analysis of long-span cable-stayed bridge

地震波峰值调整常采用基于地震动峰值加速度(PGA)的方法来实现,而现行规范中设计反应谱的峰值加速度为有效峰值加速度(EPA),建议采用EPA进行峰值调整。首先,分析PGA和EPA含义及其内在联系,总结国内外现有的EPA计算方法,根据桥梁结构与建筑结构的不同特点,修正桥梁结构时程分析EPA的计算公式。其次,研究EPA计算中地震波反应谱的平滑处理问题,并提出3种峰值平滑方法,分析相关参数的取值及各方法的优劣性。最后,将此方法应用于一座大跨度斜拉桥进行时程分析,比较基于PGA和EPA两种不同峰值调整方法下结构的位移和内力结果。结果表明,应用基于EPA的峰值调整方法得到的时程分析结果更加可靠。

The peak adjustment of seismic wave is often realized by the method based on the peak ground acceleration(PGA),while the peak acceleration of the design response spectrum in the current specification is the effective peak acceleration(EPA),and EPA is recommended for peak adjustment.Firstly,the meaning and internal relations of PGA and EPA were analyzed,and the existing EPA calculation methods at home and abroad were summarized.According to the different characteristics of bridge structure and building structure,the calculation formula of EPA for bridge structure time history analysis was modified.Secondly,the smoothing processing problem of seismic wave response spectrum in EPA calculation was studied,and three peak smoothing methods were proposed to analyze the value determination of relevant parameter and the advantages and disadvantages of each method.Finally,this method was applied to the time history analysis of a long-span cable-stayed bridge,and the displacement and internal force results of the structure based on PGA and EPA were compared.The results showed that the time history analysis results obtained by the peak adjustment method based on EPA were more reliable.