新型PEC柱(强轴)-钢梁(RBS)组合框架层间倒塌机理试验研究

Experimental study of inter-story substructure collapse mechanism of PEC column(strong axis)-steel beam(RBS) composite frame

结构抗倒塌性能是维系结构震后整体性和实现＂大震不倒＂设计标准的关键所在。为研究新型PEC柱（强轴）-钢梁（BRS）组合框架结构的层间子结构倒塌机理,按1∶2缩尺比例设计制作1榀组合框架层间子结构试件并进行拟静力抗震试验。基于试验现象记录和测试数据整理,分析了试件的破坏过程、滞回特性、水平抗侧刚度退化、耗能能力、水平侧移模式与塑性破坏机构等抗震性能。研究结果表明：对穿螺栓连接实现了节点区混凝土斜压带传力模式,且梁端截面削弱使梁端出现塑性铰远离节点区,较好满足了＂强节点弱构件＂的抗震要求;试件位移延性系数μu=4.36,最大等效黏滞阻尼比（ζeq）max=0.344,具有较好的抗震延性和耗能能力;试件水平抗侧刚度沿高度分布均匀,呈现理想倒三角形侧移模式;试件最终破坏模式为梁端削弱截面屈服形成塑性铰的理想塑性破坏机构,且其承载力下降到极限承载力85%时,对应层间相对侧移和节点转角均超过罕遇地震作用下层间侧移限值1/30,试件具有良好的抗倒塌能力。

Structural collapse resistance performance is the key to maintain structure integrity after earthquake and to realize the design target of collapse prevention at maximum considered earthquake level.In order to study the inter-story substructure collapse mechanism of an innovative PEC column（strong axis）-reduced section steel beam composite frame,a 1：2 scale specimen of composite frame inter-story substructure was designed and fabricated,then quasi-static experiment was carried out.Based on the experimental phenomena and measured data,the failure process,hysteretic behavior,horizontal lateral stiffness degradation,energy dissipation capacity,horizontal displacement mode and plastic failure mechanism of specimen were analyzed.Experimental results indicate that using penetrated bolt connection,the force transfer mode of concrete diagonal strut in panel zone was established,and the reduced beam end section causes the plastic hinge to form at the beam end is far away from the panel zone,which meets the seismic demand of ＂strong joint weak member＂.The specimen displacement ductility coefficient μu=4.36,the maximum equivalent viscous damping ratio （ζeq）max=0.344,which possesses good ductility and energy dissipation capacity.The horizontal antilateral stiffness of the specimen is uniformly distributed along the height,showing an ideal inverted triangle lateral displacement mode.The ultimate failure mode of specimen is an ideal plastic failure mechanism：yielding plastic hinge is formed at the end of reduced section steel beam.While the bearing capacity is not descending to 85% of its ultimate bearing capacity,the inter-story drift and connection rotations are all exceed the drift limit（1/30）at maximum considered earthquake level,correspondingly the specimen has sound collapse prevention capacity.