基于伸臂桁架多尺度模型的超高层建筑地震灾变评估

Evaluation of Seismic Collapse Resistance of Super-Tall Building Based on Multi-Scale Model of Outrigger

针对伸臂桁架斜腹杆在地震灾变过程中发生塑性屈曲,而宏观梁单元很难模拟塑性屈曲引起的承载力和刚度退化这一问题,以典型伸臂桁架试验为基础,在兼顾计算效率和精度的前提下,提出了基于梁单元和壳单元的伸臂桁架多尺度有限元模型;建立了典型超高层建筑的多尺度有限元模型,研究伸臂桁架塑性屈曲对地震灾变全过程的影响.结果表明,伸臂桁架多尺度模型能较好地预测初始刚度、屈服承载力以及塑性屈曲引起的承载力和刚度退化,且具有较高的分析效率;在进行超高层建筑地震灾变模拟时,不考虑伸臂桁架的塑性屈曲,会高估伸臂桁架的耗能能力,低估核心筒和巨柱的损伤程度,最终影响结构的倒塌模式并高估抗倒塌能力.

Plastic buckling of diagonal chords in outriggers has often been observed.The macro beam element has a limited capacity to simulate the strength and stiffness deterioration caused by plastic buckling.Based on the typical component seismic tests of outrigger,the multi-scale finite element(FE)model of outrigger combined with the beam and shell elements is proposed considering both accuracy and efficiency.And then the whole FE model of one typical super-tall building is built up with the proposed multi-scale model.Finally,the whole process of earthquake-induced collapse of super-tall building is discussed considering the plastic buckling of outriggers.The results indicate that the proposed multi-scale model of outrigger can accurately and efficiently predict the initial stiffness,yielding strength and the strength and stiffness deterioration caused by plastic buckling.During the earthquake-induced collapse simulation of super-tall building,the seismic energy dissipation capacity of outriggers will be overestimated and the damage of shear walls and mega-columns will be underestimated if the plastic buckling of outrigger is not considered.Consequently,these will affect the potential collapse mode and overestimate the collapse resistance of super-tall buildings.