基础刚度对高层建筑抗震性能影响研究

STUDY ON THE INFLUENCE OF FOUNDATION STIFFNESS ON THE SEISMIC PERFORMANCE OF HIGH-RISE BUILDINGS

该文建立了可以同时考虑基础刚度与地下室周边土体约束影响的结构分析模型,给出了确定单桩竖向刚度的原则与计算周边土体弹簧刚度的方法。通过对21层、32层和43层剪力墙结构在7条地震波作用下的时程分析,考察基础刚度和地下室周边土体弹簧刚度对结构抗震性能的影响。计算结果表明,考虑基础刚度后,结构自振周期加长,层间位移角增大,楼层水平剪力与倾覆力矩略有减小,地下室外墙土体反力显著增大,桩顶反力变化幅度减小。对于矩形平面的建筑,考虑基础刚度对短边方向的影响远大于对长边方向的影响。随着建筑高度与高宽比增加,考虑基础刚度引起的各种结构效应随之增大。由于高层建筑的高宽比大,侧向刚度起控制作用,基础刚度对结构抗震性能的影响值得高度关注。

A structural analysis model, which considers the influence of both the pile foundation stiffness and the restraint provided by the soil around the basement, is established in this paper. The associated principles of determining the vertical stiffness of pile, as well as the method of calculating the stiffness of the springs for the soil around the basement, are proposed. Through the time-history analyses of three shear wall structures with different stories （i.e., 21, 32 and 43） under 7 ground motions, the effects of foundation stiffness and soil spring stiffness on the seismic performance of structures are investigated. The results indicate that if the foundation stiffness is taken into consideration, the vibration periods and the inter-story drift ratios of the structure increase, while the horizontal shear forces and overturning moments slightly decrease. The reaction force acting on the exterior basement external walls provided by the soil significantly increases, while the amplitude of the variation of the top reaction force for the piles decreases. For the buildings with rectangular plane, the influences of foundation stiffness on the short edge direction are much larger than those on the long edge direction. In addition, the influence of foundation stiffness increases with the increasing of the building height and aspect ratio. Due to the relatively high aspect ratio, the lateral stiffness is generally regarded as the critical control factor for tall building. Hence, the influence of foundation stiffness on the seismic performance of structures requires further attention.