二次受力下自密实混凝土加固框架节点抗震性能试验研究

通过对3个自密实混凝土加固框架中节点和1个未加固的对比框架节点进行二次受力下自密实混凝土框架节点的拟静力试验，研究不同初始受力对自密实混凝土加固节点抗震性能的影响。柱轴压比为0.3，梁端初始力为0、0.25、0.50倍的被加固试件预估梁端开裂荷载。通过对试件破坏过程、新老钢筋应变、荷载位移滞回曲线等试验结果的分析得出：采用自密实混凝土增大截面法加固框架节点，新老混凝土的协同工作性能良好；考虑初始受力的影响，加固节点的极限荷载、极限位移、梁端位移延性系数等都会降低，且降低的程度随梁端初始荷载的增大而增大，在加固设计中应予以考虑。

Experimental study on seismic performance of frame joints strengthened by self-compacting concrete under secondary load

Three frame joints strengthened by self-compacting concrete and one unstrengthened joint were produced for comparison.Static tests using MTS servo loading system on the frame joints under secondary load were carried out to study the influence of different initial forces on the seismic performance.The initial column axial load ratio was 0.3,and the initial forces of the beam were 0,0.25 and 0.50 times the estimated cracking load of the unstrengthened specimen beam end.The results of the damage process,strain of the old steel and new steel,the load-displacement hysteretic loops were analyzed.It is found that the interactive performance of the old concrete and new concrete is good when using self-compacting concrete to strengthen the frame joints.Considering the impact of the initial load of the beam end,the ultimate strength,displacement,and beam end displacement ductility coefficient of the reinforced joints etc.are reduced.The degree of reduction increases with the initial load,which should be considered in the design of strengthening.