基于非线性静力分析的地震强度直接计算方法

Direct calculation of seismic intensity based on non-linear static analysis

依据给定延性系数下地震强度和伪加速度响应之间的正比规律,提出了根据非线性静力分析得到的结构响应求解特定地震波形下相应地震强度的直接计算方法。建议的直接计算方法基于非线性静力分析得到的能力曲线,通过建立弹塑性体系伪加速度动力放大系数与延性系数之间的函数关系,快速求解曲线上各点对应的地震强度,建立可用于新一代基于性态抗震能力分析的结构响应函数。与已有寻求特定地震强度下结构响应性态点的计算方法不同,所提出的计算方法从能力曲线上的任一点出发,求解过程中仅有一个未知量,避免了迭代或试算。它既适用于平滑的设计谱,也适用于针对特定地震波的实际反应谱。在求得的结构响应曲线上,根据特定的地震强度,可以准确地反求性态点。针对实际反应谱和设计谱,通过算例分别与采用非线性时程分析和Chopra的算例进行对照。结果表明:建议的计算方法不仅准确,而且过程直接、计算快捷。

The proportional relationship between seismic intensity and pseudo acceleration response under a given ductility factor was revealed.A procedure,which directly calculates the seismic intensity of a determined ground wave corresponding to the structural response from non-linear static analysis,was proposed.Based on the capacity curve obtained from the non-linear static procedure,the direct procedure was derived by establishing the relationship between the pseudo acceleration scale factor and the ductility factor of inelastic system.The procedure is efficient to generate the structural response function under the analytical frame of ＇Next-generation performance-based seismic design procedures＇.Different from conventional methods which search the performance point under a certain seismic intensity,the proposed procedure starts from an arbitrary point on the capacity curve.Since the proposed procedure has only one unknown parameter,iteration or trial calculation can be avoided.The procedure is suitable for the actual response spectrum of a determined ground wave,as well as the smooth design spectrum.The non-linear history analysis and a numerical example of Chopra,using actual and design spectrum,are adopted respectively to calibrate the procedure.The results show that the proposed procedure is exact and fast.