比例阻尼矩阵构建方法对高重力坝地震反应的影响

Influence of Construction Method with Proportional Damping Matrix on Seismic Response of High-gravity Dams

摘要:

通过二维数值计算，讨论合理建立阻尼矩阵对高重力坝时域内进行地震反应计算的重要性。首先，以4个不同坝高的混凝土重力坝为计算对象，将三种地震波作为水平输入，解得6种不同的阻尼矩阵形式下坝体的地震反应。然后以频域内解为标准，研究各种阻尼矩阵的合理性。研究结果表明：坝高超过250 m高的重力坝在时域内进行的地震反应计算是长周期系统的动力分析问题，应重视阻尼矩阵的建模方式，不宜采用单频率参数的质量比例阻尼矩阵和刚度比例阻尼矩阵，应采用双频率参数的Rayleigh阻尼矩阵，在确定2个频率参数时除采用坝体基频外还应考虑激振地震波的频谱特性以获得合理的坝体地震反应计算结果。

Abstract:

In this paper, we use two-dimensional numerical analysis to study the importance of establishing a reasonable damping matrix in the seismic response analysis of high-gravity dams in the time domain. First, we selected four high-gravity dams of different heights as examples and determined their seismic responses under horizontal excitation by three seismic waves using six different damping matrices. Then, the reasonability of the different damping matrices was assessed by comparing their solutions in the frequency domain. The results indicate that the seismic response in the time domain of a gravity dam with a height greater than 250 m is a dynamic analysis problem of a long-period system, and attention should be paid to the approach used to model the damping matrix. In this case, we suggest using a Rayleigh damping matrix with two frequency parameters rather than a mass-proportional damping matrix or a stiffness-proportional damping matrix with one frequency parameter. To accurately analyze the seismic responses of a dam, both the fundamental frequency of the dam and the frequency characteristics of the input seismic wave should be considered.