摘要
本文设计实现了分层土─基础─高层框架结构相互作用体系的振动台模型试验，再现了地震动激励下上部结构和基础的震害现象和砂质粉土的液化现象。通过试验，研究了相互作用体系地震动反应的主要规律：由于动力相互作用的影响，软土地基中相互作用体系的频率小于不考虑结构─地基相互作用的结构频率，而阻尼比则大于结构材料阻尼比；体系的振型曲线与刚性地基上结构的振型曲线明显不同，基础处存在平动和转动。土层传递振动的放大或减振作用与土层性质、激励大小等因素有关，砂土层一般起放大作用，砂质粉土层一般起减振隔振作用；由于土体的隔震作用，上部结构接受的振动能量较小，各层反应均较小。上部结构顶层加速度反应组成取决于基础转动刚度、平动刚度和上部结构刚度的相对大小。
In this paper, shaking table tests for dynamic interaction system of layered soil, foundation and high-rise frame structure are designed and carried out. The earthquake damage to superstructure and foundation and the liquefaction phenomenon of sandy powder soil covered by impermeable viscous soil are reproduced. Based on these tests, several key issues about seismic response of the dynamic Soi1-Structure Interaction (SSI) system are studied. Due to the effect of SSI, the nat- ural frequency of the system in soft soil condition is less than that of the structure on rigid founda- tion where the SSI is not taken into account, and the damping ratio is larger than that of the structure. The mode shape of system under the soft soil condition is notably different from that of the structure on the fixed base in that there are rocking and swing at the foundation. Magnification or reduction of vibration transferred by soil is related to soil characteristic, excitation magnitude, and so on. Com- monly, sand magnifies vibration, while sandy powder soil damps and isolates vibration. Due to the isolation of soil, less vibration energy is received by superstructure, and the response at every floor is less. The components of the acceleration response at the top of superstructure depend on the relative magnitude of rocking stiffness, swing stiffness of foundation and the stiffness of the super structure. There is little effect of vertical excitations on the key issues of the horizontal SSI. The tests demonstrate that the effect of SSI on seismic response of the system is quite notable. These tests and their plentiful experimental data lay the foundation for further theoretic and analytic research.
出处
《地震工程与工程振动》
CSCD
北大核心
2001年第3期104-112,共9页
Earthquake Engineering and Engineering Dynamics
基金
国家自然科学基金重点项目资助(编号:59823002)
