配筋PVA-钢混杂纤维增强水泥基复合材料梁柱边节点抗震性能试验研究

Experimental study on seismic performance of PVA-steel hybrid fiber reinforced cementitious composite exterior beam-column joints with steel bars

改善工程材料韧性和耐久性,提高框架梁柱节点抵抗变形和破坏的能力,是提高框架结构抗震韧性的有效途径之一。采用PVA-钢混杂纤维增强水泥基复合材料代替普通混凝土应用到梁柱边节点,考虑轴压比和加密区体积配箍率的影响,设计6个配筋PVA-钢混杂纤维增强水泥基复合材料、1个配筋单掺PVA纤维增强水泥基复合材料和1个钢筋混凝土梁柱边节点试件进行拟静力试验,分析其破坏形态、滞回曲线、骨架曲线、延性、耗能能力、钢筋应变和梁端塑性铰区转角,探讨混杂纤维的加入对梁柱边节点抗震性能的影响。结果表明:与钢筋混凝土节点和单掺PVA纤维增强水泥基复合材料节点相比,PVA-钢混杂纤维增强水泥基复合材料节点的承载力高、变形能力大、延性好、耗能能力强,抗震性能显著提升。当试验轴压比从0.12增加到0.24,梁端塑性铰区产生一定的外移,塑性性能发挥更充分,同时试件的变形能力、延性、耗能能力增加。在加密区体积配箍率减小的情况下,试件仍表现出良好的抗震性能。

One of the effective ways to improve the seismic resilience of frame structures is to increase the toughness and durability of engineering materials to improve the ability of frame beam-column joints to resist deformation and damage.PVA-steel hybrid fiber reinforced cementitious composites(HyFRCC)was used to replace ordinary concrete in exterior beam-column joints and the influence of axial compression ratio and volumetric ratio of intensified stirrups was taken into consideration to investigate the influence of the addition of hybrid fibers on the seismic performance of exterior beam-column joints.Six PVA-steel HyFRCC exterior beam-column joints with steel bars,an engineered cementitious composites(ECC)joint with PVA fiber only and a reinforced concrete(RC)joint for comparison were designed.Then quasi-static tests were conducted for all specimens.Failure modes,hysteresis curves,backbone curves,ductility,energy dissipation capacity,steel bar strain and plastic hinge rotation at beam end were analyzed.The results show that PVA-steel HyFRCC exterior beam-column joint specimens have high bearing capacity,large deformation capacity,good ductility and strong energy dissipation capacity comparing with RC joint and ECC joint specimens.The seismic performance of PVA-steel HyFRCC specimens is improved significantly.When the axial compression ratio in the experiment is increased from 0.12 to 0.24,the plastic hinges at beam end produce a certain external shift,and the plastic deformation develops more sufficiently,meanwhile,the deformation ability,ductility and energy dissipation capacity of the specimens become higher.The specimens with lower volumetric ratio of intensified stirrups still exhibit good seismic performance.