相关多点地震动合成HOP方法的分析与改进

解释了相关多点地震动合成的HOP方法具有局部场地收敛性,分析了其生成各点地震动幅值相差较大的原因。除第一点外,HOP方法生成的各点地震动自功率谱围绕真实值波动,导致某些频率的能量过大而某些频率变小。由于结构频谱的离散性,如果恰好与能量大的频率吻合,则会激发结构强烈的振动响应,反之结构的响应值偏小,这与实际不符;进行非线性响应计算时或因为某些频率能量过大而使结构进入非线性阶段,则响应的期望值也是错误的。通过对实际地震波传播机制的模拟,提出了改进的HOP的方法。算例表明,此方法具有局部场地收敛性,各点自功率谱吻合给定的目标值,进而保证了各点幅值的一致性,可以用于结构抗震非线性响应分析。

Analysis and improvement of simulation method for spatially correlative time histories of multi-point ground motions

This article shortly reviews the HOP methods for generating artificial spatially correlative time histories of multi-point ground motions, proves its local convergence and analyzes the reason for the large difference between the amplitude of different point. In HOP method, the artificial acceleration is just a sample of a random variable, so its auto-power spectrum is related to the random phase angle of every frequency component, which eventually leads to a fluctuation around the true value. Although the mathematical expectation of the artificial acceleration is correct, the resulting nonlinear seismic response of structure is incorrect. Through the actual mechanism of seismic wave propagation simulation, an improved method of HOP is proposed. Examples show that this method has a convergence at local sites. All points from the power spectrum of the target in line with the given points ensure the con-sistency of amplitude. This method can be used for the non-linear seismic response analysis.