偏心结构双向水平地震反应谱输入问题研究

Study on bidirectional horizontal seismic response spectrum inputs of eccentric structures

选择了一定数量有代表性的偏心结构,首先在水平方向与形心主轴成一定角度输入反应谱,逐渐改变输入角度,寻找反应谱输入的最不利方向,并将其最大地震反应结果作为标准值,然后采用目前国内外常用的4种反应谱输入方法分别对这些算例进行计算,并将其结果与标准值进行了比较。结果表明:对于偏心率较小的结构,4种输入方法给出的反应值,误差都很小;因此可采用其中任何一种方法。对于偏心率较大的结构,除方法1外,其余3种方法给出的结果,有多项反应值的误差远超出工程的允许误差范围。因此应采用方法1,即在结构的两主轴方向同时输入反应谱,并将其反主谱值的比例调至1∶0.3。如此求得的反应值可相似于反应谱从结构的最不利方向输入时的值。

In this paper, several representative eccentric structures are selected as analyzed examples in order to investigate bidirectional seismic input problems. First, each structure is excited by response spectrum of given in- tensity from various directions to look for the maximum response values, and then these values assumed as response standard values are compared with those response results from four different bidirectional seismic input methods, which are currently used at home and abroad. The comparison shows that for the structues with small eccentricities, the errors of response values obtained by all four input methods are small. So any one of the four methods can be used for response analysis. Howevrer for the structures with large eccentricities, except method 1, other three methods give several response values with errors exceeding remarkably the allowable error range of engineering. Thus the method 1 must be adopted, that is, the response spectrum should be inputted in two major axis directions of the structure simutaneously with intensity scale of 1： 0. 3. Therefore obtained response values can simulate ones by in- putting the response spectrum in the most unfavorable direction of the structure.