某超限高层建筑箱形基础抗震性能分析

Seismic performance analysis of box-shaped foundation of an out-of-code high-rise building

利用有限元分析软件ANSYS对地震激励下的土-结构动力相互作用体系进行了数值计算,分析了高层建筑箱形基础的抗震性能。将静态分析结果与工程实测数据对比,结果吻合较好,确保了模型的计算精度;输入El Centro波、Kobe波和上海人工波作为激励,进行非线性时程分析,研究箱形基础不同测点的水平方向位移以及与土的接触压力。结果表明：箱形基础两侧对应测点的位移时程曲线的趋势基本保持一致,表明箱形基础的各部分在地震过程中的振动是整体有序的,从而解释了箱形基础抗震性能良好的根本原因;核心筒的存在,平衡了箱形基础由形状不规则而引起的各方向刚度的差异,提高了箱形基础的抗震性能;箱形基础与土脱离和再接触的现象表明,基础在振动过程中是不断摇摆的,从而解释了地震时高层建筑倾斜、倾覆的原因,证实了基础抗倾覆能力的重要性。

The numerical calculation of soil-structure dynamic interaction under seismic excitation was carried out by using the finite element analysis software ANSYS,and seismic performance analysis of the box-shaped foundation of a high-rise building was analyzed. The data of static analysis were compared with the real measurement data in project and the result shows they are in good agreement to ensure the calculation accuracy of the model. Nonlinear time-history analysis was carried out by inputting El Centro wave, Kobe wave and Shanghai artificial wave as excitations. The horizontal displacements and the contact pressures on soil of different measuring positions of the box-shaped foundation were researched. Results show that the tendency of the displacement time-history curves of the corresponding measuring points on both sides of the box-shaped foundation are basically the same,indicating that the vibration of each part of the box-shaped foundation during the earthquake is overall and orderly,thus revealing the root cause of good seismic performance of the box-shaped foundation. The existence of the corewall balances the difference of stiffness in all directions caused by the irregular shape of the box-shaped foundation and improves the seismic performance of the box-shaped foundation. The phenomenon of separation and re-contact of the box-shaped foundation with the soil shows that the vibration of foundation in the process is constantly swinging,which explains the reasons for high-rise buildings tilt and overturning during the earthquake,confirming the importance of anti-overthrow ability of foundation.