梁桥结构地震反应分析中输入地震动选取及调整方法研究

Selecting and adjusting methods for earthquake input in a girder bridge's seismic response analysis

针对桥梁结构地震动分析时所输入地震动选择会影响时程分析结果的可靠性,结合结构动力放大系数基本原理及地震波能量原理,通过分析反应谱型特点,将其拟合归纳为以结构自振周期±30%范围及规范规定的0.1s-Tg范围分别定义为低频、高频对比区间,以两个区间反应谱曲线包围面积作为对比参数进行自然地震波选择依据。并据所选地震波提出基于两区间的5种天然地震波调整方法。以典型多跨梁桥为例进行数值分析,以桥墩墩底弯矩、剪力和及墩顶位移作为桥梁地震反应统计量。利用统计分析结果验证双参数地震波选择方法及地震波调整方法的合理性及有效性。

Time-history analysis method is the most popular seismic analysis one of bridge structures,however,selection of input seismic motion is a key factor to affect the reliability of time-history analysis results. Combining the basic principle of structure dynamic amplification coefficient and the energy principle of seismic wave. The seismic response spectrum of a bridge structure was divided into two intervals,one was a lower-frequency interval with a frequency range of± 30% the structure＇s natural vibration period,the other was a higher-frequency one with a frequency range of 0. 1 s-Tg regulated by the code. The surrounding areas fo these two intervals＇ spectral curves were taken as comparative parameters to choose natural seismic wave records. Five adjusting methods of natural seismic wave records based on the above mentioned two intervals were presented here. In addition,seismic response numerical analysis of a typical multi-span bridge was performed,bridge pier bottom moment,base shear and pier top displacement were taken as statistical values of the bridge＇s seismic responses. Numerical analysis results showed that the double-parameter selecting and adjusting methods for seismic wave records are reasonable and effective.