煤矸石混凝土梁柱节点抗震性能试验

Experiment on seismic performance of coal gangue concrete beam-column joints

关键词:  煤矸石混凝土  拟静力试验  框架十字节点  抗震性能  骨架曲线

Key words:  coal gangue concrete  quasi-static test  beam-column cross joint  seismic performance  skeleton curve

摘要:

为研究煤矸石混凝土梁柱节点的抗震性能,对6个足尺试件进行低周往复加载试验。对各试件的破坏模式、滞回曲线、骨架曲线、刚度退化、耗能能力等抗震指标进行分析,研究煤矸石骨料取代率（0、30%、50%、100%）和梁纵筋配筋率（0.67%、1.34%、2.09%）对抗震性能的影响。结果表明:节点破坏模式分为梁端弯曲破坏和节点区受剪破坏,破坏现象主要表现为节点区出现大量裂缝和梁端混凝土大量剥落,煤矸石混凝土梁柱节点破坏较普通混凝土的破坏更剧烈；煤矸石取代率低的试件的滞回曲线饱满,刚度退化慢,延性好,有较好的抗震性能；随着煤矸石取代率的增大,试件的滞回曲线有明显捏缩效应,且刚度退化加快,延性及耗能变差。增大梁纵筋配筋率可改善梁端混凝土的损伤,提高承载能力,但过高的配筋率将诱发节点发生剪切破坏,降低耗能能力和延性。

Abstract:

To study the seismic performance of coal gangue concrete beam column joints, six full-scale specimens were prepared and subjected to low-cycle repeated loading tests. The analysis focused on various seismic indicators, including failure modes, hysteresis curves, skeleton curves, stiffness degradation, energy dissipation capacity. The effects of coal gangue aggregate replacement rates (0,0%, 50% and 100%) and beam longitudinal reinforcement ratios (0.67%, 1.34%, and 2.09%) on the seismic performance were studied. The results showed that the failure modes of joints are bending failure at the beam end and shear failure at the node area. The failure primarily manifests as extensive cracking in the joint area and significant spalling of concrete at the beam ends, with coal gangue concrete beam-column joints exhibiting more severe damage compared to ordinary concrete. Specimens with low coal gangue replacement rates displayed full hysteretic curves, slow stiffness degradation, good ductility, and good seismic performance. As the replacement rate of coal gangue increases, the specimens exhibits a pronounced pinching effect in the hysteretic curves, along with accelerated stiffness degradation and reduced ductility and energy dissipation. Increasing the longitudinal reinforcement ratio of the beam can improve the damage to the concrete at the end of the beam and enhance its bearing capacity. However, excessively high reinforcement ratio may induce shear failure of the nodes, reducing their energy dissipation capacity and ductility.