大跨隔震结构竖向地震响应的振动台试验研究

为研究大跨隔震结构竖向地震响应，首先对一大跨网架隔震结构1∶20的缩尺模型进行了振动台试验，对比研究隔震前后模型的动力特性及其在双向和三向地震动输入下的加速度及位移等动力反应，进而对大跨隔震结构的网架和一般楼层(首层和转换层)的竖向减震效果进行了分析。结果表明大跨隔震结构的网架在双向地震和三向地震输入下都具有非常明显的水平减震效果，且减震率大于一般楼层；大跨隔震结构的一般楼层基本没有竖向减震效果，而在输入地震强度比较小的情况下网架竖向加速度基本没有减小，甚至稍有放大，但随着输入地震强度的增加，网架的竖向加速度减震率逐渐提高；对于网架的竖向位移响应，基础隔震模型在罕遇地震下有较明显的减震效果。最后建立了相应大跨隔震结构与非隔震结构的有限元分析模型，并对隔震支座进行参数优化，结果表明屈重比取4%~6%时，大跨网架隔震结构具有较小的基底剪力。

Shaking table test on vertical seismic responses ofisolated large-span structure

The shaking table test of a 1∶20 scale isolated large-span grid structure model was carried out to study the vertical seismic responses. The dynamic characteristics of the model and the acceleration and displacement responses of the structure under the action of horizontal two directional (2D) and three directional (3D) earthquakes were studied in case of with and without isolation. Then, the vertical vibration reduction of the grid and normal floors of the isolated large-span structure was analyzed. The test results show that the grid of the isolated large span structure has greater horizontal damping effect than the normal floor under both 2D and 3D seismic input. The normal floors of the isolated large-span structure basically have no vertical damping effect. The vertical acceleration of the large-span grid shows slight decrease or even increase when the earthquake intensity is relatively small. However, the damping effect of vertical acceleration of the large-span grid increases with the earthquake intensity. The vertical displacement responses of the large-span grid subjected to rare earthquake have obvious damping effect. Finally, the numerical models of the large-span structures with and without isolation were established to optimize the parameters of isolation bearing. The numerical results show that, to minimize the base shear of the isolated large-span structure, the optimal yield ratio is 4%-6%.