应用改进非线性分层壳模型的超高层框架——核心筒结构强震响应分析

SEISMIC RESPONSE ANALYSIS OF SUPER HIGH-RISE FRAME-CORE TUBE STRUCTURE USING IMPROVED NONLINEAR LAYERED SHELL MODEL

该文开发了一种适用于模拟超高层建筑中钢筋混凝土剪力墙的分层壳模型。超高层结构中剪力墙的截面尺寸会随着高度的增加不断减小,因此底层墙体的厚度与顶层墙体存在较大差异,导致NLDKGQ壳单元模拟超高层剪力墙构件力学性能不足。基于广义协调理论构造的厚薄板通用元TMQ对四边形平板壳单元NLDKGQ进行了改进,使其可以有效地模拟超高层剪力墙平面外的性能,并结合自行编制的混凝土二维膜材料开发了适用于模拟超高层剪力墙构件的分层壳模型。将提出的分层壳模型集成到自行开发的程序平台中,对板元采用缩减积分来克服可能的剪切闭锁问题,并依次应用于混凝土板、剪力墙构件及框剪结构的计算分析,验证了提出模型的合理性和可靠性;通过分析得出,当结构中剪力墙构件的数量较多、厚跨比较大且剪切效应明显时,建议采用能够考虑面外剪切的壳元。最后,对超高层框架—核心筒结构模型进行动力时程分析得出,是否考虑剪力墙构件的剪切变形对于整体结构的宏观响应影响较小,但对底层重要位置剪力墙构件非线性行为影响较大,因此很有必要开展针对超高层剪力墙壳元的研究。

An attempt is made to develop a modified layered shell element model specialized in simulating reinforced concrete（RC） shear walls in super high-rise buildings. Due to its deficiency for shear walls with significant variation of thickness-to-length ratio from along the structural height of general super high-rise buildings, a quadrilateral flat shell element NLDKGQ is improved in the model by the replacement of a thin-thick plate element TMQ, which is based on the generalized conformation theory, as well as by a membrane concrete material developed previously. The improvement with the TMQ endows the NLDKGQ element by capability to simulate efficiently the out-of-plane performance of shear walls with variable thickness-to-length ratios. The shear locking is avoided by the utilization of reduced integration scheme and then its accuracy is demonstrated by the test results of a RC concrete slab, four in-plane RC shear walls, and a frame-shear wall structure. The adoption of shell elements with out-of-plane performance is recommended when the structure possesses obvious shear effect and large number of shear walls with relative large thickness-to-length ratios. Afterwards, the improved model is incorporated into a self-developed program to carry out a nonlinear dynamic time history analysis on a 250 m＋ frame-core tube super high-rise building. The significance of studying the shell elements for super high-rise building indicates itself as the shear deformation of shear wall components has little influence on overall structural responses but in-negligible impact on the shear walls in structural bottom stories.