基于多点激励位移输入模型的跨断层桥梁地震动输入方法

Earthquake motion input method for bridges crossing fault based on multi-support excitation displacement input model

探讨了多点激励位移输入模型对跨断层桥梁的适用性,并针对包含永久地面位移的时程曲线在基线校正过程中存在的问题提出了一种改进的基线修正方法.利用该方法对集集地震中距发震断层最近的10个强震台站地震动记录进行基线校正,校正后的永久地面位移与GPS测站同震位移运动方向一致,数值相近,由此验证了该方法的合理性,所得位移时程曲线可作为多点激励位移输入模型的地震动输入.以某跨断层桥梁为例,分别采用多点激励位移输入模型和多点激励加速度输入模型计算结构地震响应.结果表明,基于多点激励位移输入模型的地震动输入方法能够真实模拟断层错动引起的结构残余变形与内力,符合实际震害特征;而基于多点激励加速度输入模型的地震动输入方法则未考虑该残余变形与内力,故可能导致不合理的计算结果.

The applicability of the multi-support displacement input model in bridges crossing fault（ BCF） is discussed,and an improved baseline correction method is proposed to solve the problem in the process of baseline correction to ground motion time history containing the permanent ground displacements. By using this method,the ground motion records of the nearest 10 strong motion stations in the Chi-Chi earthquake are corrected. The directions of the corrected permanent ground displacements and the co-seismic of GPS stations are the same,and the values are similar,which proves the rationality of the improved method. The displacement time history can be used as the ground motion input of the multi-support displacement input model. A BCF is taken as an example,and the seismic responses of the structures are calculated by using the multi-support excitation displacement input model and the multi-support excitation acceleration input model. The results showthat by using the earthquake motion input method based on the multi-support displacement input model,the residual deformation and internal force of the structures caused by fault dislocation can be truely reflected and the calculation results match with the actual characteristics of seismic damage.However,without considering the residual deformation and internal force,the earthquake motion input method based on the multi-support excitation acceleration input model may lead to unreasonable results.