不同配筋形式钢筋混凝土框架变梁节点抗震性能试验研究

Experimental study on seismic behavior of interior joints with different types of reinforcement arrangement in reinforced concrete frame structures

完成6个1/3比例钢筋混凝土框架变梁中节点试件低周反复荷载试验,重点研究了小梁交叉弯折纵筋(即"X"筋)、梁垂直加腋等配筋构造措施对变梁节点抗震性能的影响。研究结果表明:增加节点区配箍率和小梁采用交叉弯折纵筋后节点组合体仍发生了核心区剪切破坏,表明此种配筋方式对该类非常规节点抗震性能的改善不明显;小梁底部垂直加腋后,在小梁与加腋界面处发生破坏,避免了节点区的剪切破坏,从而改善了变梁节点的抗震性能。此外,轴压比变化对变梁节点抗震性能的影响不显著,增加核心区配箍率则可以增大节点组合体剪力、减小核心区裂缝间距和宽度,从而改善变梁中节点的抗震性能。

Six specimens of interior joints were tested under reversed cyclic loading.The experimental study was conducted,which focused on the effect of low beam with X-shape reinforced bars and vertical haunched beam on seismic behaviour of interior joints.Test results indicate that the seismic behavior of beam-column joint subassemblage is improved little by the construction measures of X-shape bars in the low beam,and the failure modes of those specimens are still joint shear failure.On the contrary,the joint shear failure process of the specimen is delayed by the application of vertical haunched beam,and the behavior of this new type joint is improved greatly due to the flexural failure formed in the connection between the low beam and the expanded joint core.In addition,the seismic behaviour of the tested specimens is not influenced by the axial compression ratio but influenced by the joint hoop percentage.With the increasing of joint hoop percentage,the shear strength of the beam-column joint subassemblage increases,the width and space of diagonal cracks become smaller than that of the control specimens.