基于三角函数的脉冲型近场地震动的近似模型

An analytical model for approximating pulse-like near-fault ground motions

对用于模拟脉冲型地震动的Makris模型的适用性进行了评价,通过对脉冲周期的计算方法的比较分析,发现从该模型推导的由实测最大位移和最大速度计算得到的周期过小估计了近场地震动的脉冲周期。考虑地震动正负速度幅值的不同,提出了一种新的基于三角函数的脉冲型近场地震动的近似模型,该模型用于具有单循环的脉冲型地震动,可模拟位移完全不复位、完全复位和部分复位的地震动。通过比较实测地震动和近似模型的时程曲线和反应谱,证明新模型具有较好的适用性。

Analytical models based on trigonometric functions are used to describe the pulse-like near-fault ground motions, and Makris model is one of the typical. In this paper, the Makris model was investigated first. It is found that the pulse period obtained analytically from the peak displacement and peak velocity underestimates the predominant period of the record. A new analytical approximation model was proposed to consider the difference of maximum and minimum velocity in the main cycle of velocity time history. The model could be applied to simulate those one-cycle pulse ground motions, including the motions with forward displacement, forward-backward displacement and forward-partially backward displacement. Examples were also presented to show that the new approximation model was useful to simulate the one-cycle pulse type ground motions. © 2017, Editorial Office of Journal of Vibration and Shock. All right reserved.