轴压比和面承板厚度对混合节点抗震性能的影响

Effects of axial compression ratio and face-bearing plate thickness on seismic performance of hybrid joints

为了研究新型柱全截面隔板式钢筋混凝土柱-钢梁(RCS)混合框架节点形式的抗震性能,考虑不同轴压比和面承板厚度的影响,对2组共6个3/4比例的梁柱节点进行低周往复加载试验研究.试验中所有试件均发生设计预期的节点剪切破坏,滞回曲线呈弓型,表明节点具有良好的抗震性能.试件最终因节点区的混凝土开裂剥落而丧失承载力.试验结果表明,当轴压比为0~0.25时,随着轴压比的增大,RCS节点开裂荷载有所增大,峰值荷载前斜裂缝数量减少、宽度减小,试件的承载力、刚度和耗能能力均有所提高.节点域柱纵筋黏结应力随轴压比增大而减小,表明节点域内黏结状况有明显改善.相较于单向面承板试件,双向面承板试件在承载能力、延性和耗能能力方面均表现出显著提高;当双向面承板厚度由6 mm增加至10 mm时,试件峰值承载力和刚度的提升幅度相对有限.

The influence of different axial compression ratios and face-bearing plate thicknesses was considered,in order to investigate the seismic performance of a new whole column-section diaphragm type reinforced concrete column-steel beam(RCS)hybrid frame joint.Two groups of six 3/4 scaled beam-column joints were subjected to low-cycle reversed loading tests.All specimens experienced the expected joint shear failure,and the hysteresis curve showed a bow shape which indicated that a good seismic performance was available for the novel joints.Eventually,the specimens lost their bearing capacity due to concrete cracking and spalling in the joint region.The test results showed that,within the range of axial compression ratios from 0 to 0.25,the cracking load of the RCS joints increased with the increase of the axial compression ratio.The number of diagonal cracks appearing during the phase preceding the peak load diminished,accompanied by a reduction in their width,and the bearing capacity,stiffness,and energy dissipation capacity of the specimens all improved.The bonding stress within the joint region also diminished as the axial compression ratio increased,indicating a pronounced enhancement in the bonding condition within the joint.Compared to the unidirectional face-bearing plate specimens,the bidirectional face-bearing plate specimens exhibit significant improvements in bearing capacity,ductility,and energy dissipation capacity.The increase in the thickness of the bidirectional face-bearing plate from 6 mm to 10 mm has a relatively limited effect on the peak bearing capacity and stiffness of the specimens.