土-结构相互作用效应对结构基底地震动影响的试验研究

Experiment study on effects of dynamic soil-structure interaction on foundation motions of structures

利用土与结构动力相互作用振动台模型试验数据,通过各种试验工况下土层表面与基础表面加速度反应的比较,深入探讨了土与结构动力相互作用效应对高层建筑结构基底地震动的影响。从输入地震动频谱特性、输入地震动强度水平和上部结构动力特性3个方面详细分析了与SSI效应对高层建筑基底震动影响程度有关的一些因素。结果表明:SSI效应对高层建筑基底地震动的影响与输入地震波的动力特性有很大关系。在地震动的频谱成分方面,SSI效应对高层建筑基底地震动的影响主要体现为土层表面和基础表面在与输入地震动卓越频率相近处的频谱成分有较大差异;SSI效应对高层建筑基底地震动的影响程度随着输入加速度峰值水平的增加而减小;在某一特定地震波作用下,当上部结构的振动频率与地震地面运动的卓越频率相近时,SSI效应对高层建筑基底地震动的影响较为强烈。

In this paper, based on the shaking table tests of soil-structure interaction (SSI) systems, effects of dynamic SSI on foundation motion of high-rise building are discussed through the comparisons between the acceleration responses of soil surface and base surface under all the work conditions of the shaking table tests. Some factors connected with effects of SSI on foundation motions are analyzed. These factors are the frequency characteristics and intensity of input ground motions and the dynamic characteristics of structure. The analysis results show that the effects of SSI on foundation motions of high-rise building are related to the input ground motion characteristics. In the respect of spectrum shape, the difference of Fourier spectrum between soil surface and base surface is mainly embodied in the spectrum values near the distinguished frequencies of input ground motion. The analysis results also show that the effects of SSI on the foundation motions will weaken with the increasing of the intensity of input ground motion. The effects of SSI on foundation motions of high-rise building may strengthen if the vibration frequencies of superstructure are approaching to the distinguished frequencies of the ground motions.