矩形钢管混凝土柱-混凝土梁搭接式节点抗震性能研究

Research on Seismic Performance of Lap Connection Between Rectangular CFST Column and RC Beam

在现有钢管混凝土柱与混凝土梁连接形式基础上,提出一种新型搭接式钢管混凝土柱-混凝土梁节点,通过低周反复荷载试验和数值模拟分析,研究了节点的破坏形态、承载能力、刚度退化、延性及耗能能力等,分析了梁端纵筋和搭接牛腿翼缘的应变发展规律。结果表明:钢管混凝土柱-混凝土梁搭接式节点表现出典型的混凝土梁端塑性铰破坏模式,符合“强节点、弱构件”的抗震设防理念;节点的滞回曲线饱满,捏缩现象较轻,刚度退化明显,强度退化较小,具有较好的延性及耗能能力;梁纵筋及牛腿各测点中搭接牛腿端部截面应变最大,通过搭接连接方式可实现梁端弯矩和剪力的有效传递,但搭接牛腿长度不足会使节点发生锚固破坏;在节点设计时,应保证足够的搭接长度,以实现钢筋混凝土梁纵筋在弯剪复合受力状态下锚固性能的可靠性,充分发挥节点的抗震耗能能力;有限元计算结果与试验结果吻合良好,该模型能够准确反映节点在实际受力情况下的力学特性,所得结论可为此类新型搭接式节点工程应用提供技术支撑。

A new type lap connection between concrete-filled steel tubular(CFST)column and reinforced concrete beam was proposed on the basis of current connection forms of CFST column and reinforced concrete(RC)beam.The failure mode,bearing capacity,stiffness degradation,ductility and energy dissipation capacity of the connection were studied by low cyclic loading test and numerical simulation analysis.The strain development law of longitudinal reinforcement at beam end and lap corbel flange was analyzed.The results show that the lap connection of CFST column and RC beam shows a typical failure mode of plastic hinge at the end of concrete beam,which accords with the seismic fortification concept of“strong connection and weak member”.The hysteretic curve of the connection is full,the pinch phenomenon is light,the stiffness degradation is obvious,the strength degradation is small,and the connection has good ductility and energy dissipation capacity.The cross section strain at the end of lap bracket is largest among measuring points of longitudinal reinforcement and corbel.The effective transfer of bending moment and shear force at beam end can be realized by lap connection,but the insufficient lap corbel length will lead to anchorage failure.In the design of connections,enough lap length should be ensured to realize the reliability of anchorage performance of longitudinal reinforcement of reinforced concrete beam under the condition of bending shear composite force and give full play to the seismic energy consumption capacity of the connections.The finite element results are in good agreement with the experimental data.The model can accurately reflect the mechanical characteristics of the connections under the actual stress.The research results can provide technical support for the engineering application of this new type of lap connections.