轴压PVC-FRP管混凝土中长柱试验研究

Experimental Study on PVC-FRP Confined Long Concrete Column Subjected to Axial Compression

通过10根PVC-FRP管混凝土中长柱轴压性能试验研究,探讨PVC-FRP管混凝土中长柱受力性能以及PVC-FRP管对核心混凝土承载力的提高效果,分析长细比对试件承载力、变形以及破坏形态的影响.试验研究表明:PVC-FRP管混凝土中长柱的受力过程经历弹性阶段、裂缝开展阶段和强化阶段;试件破坏形态表现为中部多条FRP条带被拉断,PVC管被压碎;随着长细比的增加,试件的承载力、轴向极限应变和环向极限应变逐渐减少,轴向极限应变降低的幅度比承载力降低幅度要大.PVC-FRP管混凝土中长柱的应力-应变关系曲线可以分为两个阶段:第一阶段的应力-应变曲线为抛物线,与素混凝土柱基本相似;第二阶段的应力-应变曲线为强化段,不同长细比试件强化段的斜率基本相同,试件破坏前,其应力和应变一直处于增加状态.在试验研究基础上,提出PVC-FRP管混凝土中长柱承载力和轴向极限应变的计算公式,建立PVC-FRP管混凝土中长柱应力-应变关系模型.研究结果为PVC-FRP管混凝土柱的研究和应用提供了参考.

This paper presents an experimental study on 10 PVC-FRP confined long concrete column subjected to axial compression, the mechanical behavior and the increasing ratio of bearing capacity due to the confinement of PVC-FRP tube were studied, the effect of the slenderness ratio on bearing capacity, deformation and failure mode were analyzed.Experimental results show that the loading processes of PVC-FRP confined long concrete column include the elastic stage, crack development stage and strengthening stage;The performance of failure is that the FRP strips in the middle height of specimens is fractured and the PVC tube is crushed;The bearing capacity, the axial strain and lateral strain gradually reduce with the increment of the slenderness ratio, the decreased degree of the axial strain is greater than that of the bearing capacity.The stress-strain relationship curves of PVC-FRP confined long concrete column may be divided into two sections：In the first section, the stress-strain relationship curves is parabola, which is similar to that of unconfined concrete; in the second section, the stress-strain relationship curves take on the strengthening stage, the strengthening slope keeps constant for the specimens with different slenderness ratio, and the axial stress and strain are in increment condition all along before the failure of the specimens. Based on the experimental results, the calculating formula of the bearing capacity and axial strain of PVC-FRP confined long concrete column are proposed, and the stress-strain model of PVC-FRP confined long concrete column are also established.The research results may provide reference for further study and application of PVC-FRP confined concrete column.