土-结构相互作用体系合成模态阻尼比的振动台模型试验研究

本文籍振动台模型试验。研究了SSI体系的合成模态阻尼比问题。文中首先阐明了在SSI体系直接动力分析中应采用合成模态阻尼比的观点。研究了合成模态阻尼纟的实测确定方法。并在不同工况下，通过对模型不同部位测点的传递函数，基本频率，基本合成模态阻尼比等实测数据考虑，验证了SSI体系合成模态的存在性，合成模态阻尼比与相同应变下不考虑相互作用的单纯地基土体或刚性地基结构阻尼比的差异性及其在递增动力作用下的变化规律。

Shaking Table Experimental Study on Composite Modal Damping Ratio of SSI System

Based on the shaking table tests, the composite modal damping ratio of a soil-structure interaction system was studied by using system-identification method. Firstly, the composite modal damping ratio should be adopted in dynamic analysis of SSI system, and then the method how to estimate the composite modal damping ratio of SSI system was illustrated. Finally, throughout the experimental investigations of the transfer functions, the natural frequency and the damping ratio at different position of the system, the existence of composite modal of SSI system was proued, and there is a large difference between the composite modal damping ratio of SSI system and the modal damping ratio of fixed-base structure or one of soil without SSI effect. It also shows that the composite modal damping ratio varies with increasing simulated earthquake excitations.