地震作用下大底盘双塔结构层剪力分布研究

Seismic analysis on the distribution of story shear of two-tower structures with large base

针对地震作用下某多塔结构工程实例中出现的层剪力"内缩"现象,利用SATWE软件构造一个简化的多塔大底盘结构模型,并在模型中重现了该现象。对多塔模型进行了时程分析和反应谱分析,时域上各塔振动的不同步、频域上各塔底部剪力在某些振型下存在相位差是导致层剪力内缩的主要原因。研究了水平地震作用下带裙房楼层的剪力分布,结果表明裙房顶层竖向构件分担的剪力与其抗侧刚度不成比例,两塔之间的柱剪力显著偏大。分析了裙房对塔楼的嵌固作用对塔楼层剪力产生的影响,并解释了塔楼发生剪力突变的原因,提出设计建议。

A simplified two-tower structure was established in SATWE where story shear reduction was intentionally created under seismic action, exemplifying an actual project in which the same phenomenon was detected. Time history analysis and response spectrum analysis were carried out, indicating that non-synchronization in time-domain and phase difference in frequency-domain were the main reasons to this phenomenon. Shear force distribution within the skirt building under horizontal seismic action was studied, revealing that shear forces of the columns were not in proportion to their lateral stiffness-columns between the two towers bear much larger shear force. Fix-end effect of the skirt building to the tower was studied to account for the radical change of shear force of the towers.