不对称连体双塔楼结构的动力分析

Dynamic analysis of an asymmetry double-tower connecting building

根据一不对称连体双塔楼实际工程建立了考虑楼板面内弹性变形的高精度有限元空间质点系计算模型,进行了采用BlockLanczos求解技术的模态分析和单点加速度响应谱分析.通过对有连体双塔楼结构和相应的无连体双塔楼、单塔楼的自振周期、振型、模态系数、有效质量等的比较,表明连体增强了结构的整体性,使各阶模态中既有两单塔楼各自的模态成分,也有连体、裙房对整体结构的贡献,在计算地震作用效应时所选用的振型数可比无连体的双塔楼选用的振型数少;同时连体也增大了结构刚度沿竖向分布的不均性,使两单塔楼在连体的交界处振动变形的变化率较大,出现大的内力.结构的不对称性会使扭转振型的出现提前,加大了各阶模态中扭转振动的成分,使振型更为复杂.

According to a construction project of an asymmetric double- tower connecting tall building,a three- dimension calculating model considering the in- plane elastic deformation of floor was built. The high- precision finite element method with beam and shell elements was used. Mode- frequency analysis with Block Lanczos solution and single- point acceleration response spectrum analysis were applied to study the structural dynamic performance. The first 20 periods,modal shapes,mode coefficients and effective mass fractions of the building with the connection were calculated and compared with those of a building without the connection and single- tower buildings. It was shown that the connection reinforces the whole structure. The modes contained not only the modes component of two single- tower buildings respectively, but also the contribution of the connection and the podium. Analysis of the seismic resistance capacity of a double tower connecting building shows that number of effective vibration modes of a building with the connection is less than that of a building without the connection. Also,the connection enlarges the non- uniform distribution of structural stiffness along the height. The rate of vibration shape change is large and the internal forces may be increased at the intersection of the connection. The twist mode shape occurred in advance and the twist component in every mode is increased because of the structural asymmetry.