FRC连梁联肢剪力墙数值模拟及设计方法:联肢剪力墙中连梁的主要作用
摘 要：运用有限元软件ABAQUS建立剪力墙数值模型，分别对2个对称双肢剪力墙试件和2个塑性铰区采用纤维增强混凝土(FRC)的悬臂剪力墙试件在低周反复荷载作用下的抗震性能进行数值计算，计算结果与试验结果比较吻合，表明该模型可较准确地分析FRC连梁联肢剪力墙构件在低周反复荷载作用下的抗震性能。利用所建立的数值模型，讨论了联肢墙中用FRC连梁替代普通混凝土连梁的优越性，并探讨了耦合率对FRC连梁联肢剪力墙抗震性能的影响。结果表明，用FRC替代普通混凝土作为连梁基体，可以显著提高联肢剪力墙结构的耗能能力和延性，增大其初始刚度，减缓刚度退化程度；随着联肢剪力墙耦合率的增加，联肢剪力墙的刚度和承载力提高，但当耦合率过大时，形成强连梁体系，结构的延性和耗能能力将显著下降。
关键词：纤维增强混凝土；联肢剪力墙；低周反复荷载；抗震性能；刚度；延性
中图分类号：TU973.16
文献标志码：A
文章编号：1674-4764（2012）04-0072-08
Numerical Simulations and Design Method of Coupled Wall System with FRC Coupling Beams
CHE Jialing, LIANG Xingwen, DANG Zheng，DENG Mingke
(Xian University of Architecture and Technology, Xian 710055, P. R. China)
Abstract:Using the software, ABAQUS, accurate simulations of seismic behavior of 2 coupled wall specimens and 2 cantilever structure wall specimens using high performance fiber reinforced concrete (FRC) in plastic hinge under quasi-static cyclic loading were carried out. The analysis model proves to be effective with the accordance between results of computation and experiment, then it can be used to analyze the seismic behavior of coupled wall system with FRC coupling beams. By using the verified numerical model, the ability of FRC coupling beams instead of RC coupling beams to provide acceptable performance was discussed. In addition, the impact of coupling ratio on seismic behavior of coupled walls was studied. The results show that coupled walls in which FRC coupling beams are used instead of traditional RC beams have good energy dissipation and ductility, and its initial stiffness is increased and stiffness degradation is slow. And as the coupling ratio of coupled wall structures increases, the stiffness and strength increase. But if the coupling ratio is too large, the ductility and energy dissipation capacity will be significantly reduced.
Key words:high performance fiber reinforced concrete (FRC); coupled wall; pseudo-static; seismic behavior; stiffness; ductility
联肢剪力墙是指当剪力墙沿竖向开有一列或多列较大洞口，其截面变形不再符合平截面假定的剪力墙，其水平力由各墙肢抗弯和墙肢轴力组成的力矩共同抵抗。联肢剪力墙中，连梁在相邻墙肢之间起的传递作用被称为连梁与墙肢的耦合作用，可用于抵抗部分由基底剪力引起的倾覆弯矩。已有震害及研究表明，在联肢剪力墙结构中，当墙肢底部的抗震抗剪能力得到充分保证时，强震作用下的屈曲后非弹性变形将主要出现在各层连梁端部，使墙肢整体发生能量耗散，而非集中于其塑性铰区。因此，合理设计连梁，可使联肢墙结构比悬臂剪力墙具有更高的强度、刚度和能量耗散能力，避免墙肢塑性铰区过早发生破坏，提高剪力墙的利用率和经济效益。
由于结构功能及设计要求，联肢墙结构中常用跨高比为0.5～2.5的小跨高比连梁，其主要受力特点是剪弯比偏大，在达到所需延性之前易发生剪切失效。20世纪70年代，Park等［1］提出了具有高延性和高耗能的交叉暗柱式配筋连梁，缺点是用钢量大，施工困难。针对交叉暗柱式配筋的缺点，各国学者又相继提出了菱形桁架式［2］、三层封闭约束箍筋［3］、复合斜筋［4］等配筋方案。另一种研究思路是采用高性能纤维增强混凝土（简称FRC）替代普通混凝土。FRC具有高延性和高可持续性，其主要特点是仅使用体积掺量约2%的纤维便可获得3%以上的拉应变，且拉伸时出现准应变硬化现象［5］。文献［6］通过试验研究了2个FRC小跨高比连梁试件的抗震性能，研究表明，采用FRC替代普通混凝土，可减少连梁箍筋和斜筋拉结筋的数量，经济效益良好。