基于目标功率谱和包线的地震动合成

本文给出了以目标功率谱和目标包线函数为双目标函数的人工地震动合成方法,使人工地震动不仅符合目标功率谱,还基本符合目标包线函数,并对加速度基线进行了调整,使速度时程和位移时程更为合理。作者认为如果用反应谱作为目标谱,生成的人工地震动时程可能会弱化地震动的随机特性,用这样的人工地震动时程作为输入来分析建筑结构的非线性动力反应,不是理想的选择。对建筑结构进行非线性时程分析时,用基于功率谱的人工地震动作为输入,应当是一种更为合理的方法。作者认为平方和具有明确的物理意义,是随机信号的总能量参数,并通过理论分析和数值计算,对于一定持时的随机平稳信号样本,平方和(持时×平方平均值)对振幅起重要控制作用。平方和、归一化功率谱、时域包线函数是基于功率谱模型的地震动三要素。

Artificial ground motion based on target power spectra and envelope

This article presents a method that takes the power spectrum and the enveloping curve as double target functions to synthesize the artificial ground motion. The method not only makes the spectrum of the artificial ground motion comply with the target spectrum, but also in the iterative process adjusts the ground motion wave-shape to conform to the goal enveloping curve function approximately, and eliminates the base-line shift in the acceleration time history, then makes the velocity and displacement time histories of ground motion more reasonable. The authors argue that the synthetic method based on the response spectrum may weaken the random characteristics of ground motion, and hence it may be imperfect to use the artificial ground motion based on response spectrum as an input to analyze the elastic-plastic structures. Using the artificial ground motion based the power spectrum model in elastic-plastic structure dynamic analysis may be one more reasonable alternative. The authors see that the sum of squares has the explicit physics significance, which is the total energy parameter of random signal. Through the theoretical analysis and the numerical calculation, the authors think that the sum of squares (Means of squares multiplied by duration) is an important control factor in the amplitude of a stochastic statistical signal sample with certain duration. Consequently, the sum of squares, the normalized power spectrum, and the enveloping curve function in time domain are three essential factors of the ground motion based on the power spectrum model.