隔震结构由于其优越的抵御地震能力而在实际建筑工程中得到了广泛的应用。针对建筑隔震结构,我国GB 50011—2010 《建筑抗震设计规范》所推荐的水平向减震系数法,通过引入水平向减震系数修正未采取隔震措施结构的反应谱法结果,间接获得采取隔震措施后结构的地震响应。该法具有较强的操作性,但其合理性一直受到工程界的关注。针对隔震结构的局部非线性行为,建立隔震结构地震响应的时域显式表达式,利用其降维列式优势实现隔震装置局部非线性自由度的高效降维迭代计算。结合随机模拟方法,统计获得非线性隔震结构在地震作用下的层间剪力。在此基础上,针对等效线性隔震结构反应谱法得到的层间剪力进行校准,获得各楼层层间剪力校准系数,然后采用该系数调整反应谱法计算得到的等效线性隔震结构各楼层的构件内力。采用所提出的层间剪力校准系数法和规范推荐的水平向减震系数法,对两个基础隔震结构进行地震作用效应分析,结果表明所提出方法能有效提高隔震结构地震响应的计算精度。
Isolated structures have been widely used in engineering practice owing to their superior seismic performance. The seismic isolating coefficient method, recommended by the GB 50011—2010 ‘Chinese code for seismic design of buildings’, is used for seismic response analysis of isolated building structures, in which the seismic isolating coefficient is introduced to modify the seismic responses of the corresponding non-isolated structures obtained with the response spectrum method, and the modified responses are regarded as the seismic responses of the isolated structures. Though the above code method is of easy operability, considerable attentions have been paid to investigate its rationality by engineers. In view of the local nonlinear behaviors of isolated structures, a highly efficient dimension-reduced iterative algorithm was first developed for the calculation of the degrees of freedom related to the nonlinear isolators by use of the time-domain explicit expressions established for dynamic responses of the isolated structure. Then the proposed algorithm was used to conduct the repetitive sample analyses with Monte-Carlo simulation to obtain statistically the interstorey shear forces of the nonlinear isolated structure. On this basis, the interstorey shear force calibration coefficient for each storey could be defined as the ratio of the interstorey shear force of the nonlinear isolated structure to that of the equivalent linear isolated structure obtained by the response spectrum method. Thereafter, the structural member forces for each storey could be adjusted using the corresponding interstorey shear force calibration coefficient. The interstorey shear force calibration method and the seismic isolating coefficient method were carried out for the seismic analyses of two base isolated structures. The result indicates that the proposed method can effectively enhance the calculation accuracy for the seismic responses of isolated structures.
Journal of Building Structures
isolated building structure
explicit time-domain method
interstorey shear force calibration method
seismic isolating coefficient method