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为研究钢柱负载状态下加固后的受力性能及破坏特征,进行了7根负载下外包钢筋混凝土加固的工字形钢柱和1根未加固钢柱的轴压静力试验。通过改变初始负载大小、混凝土强度、配箍率3个参数,观察加固前后轴压柱受力的全过程和破坏形态,分析负载下加固前后轴心受压柱的荷载-挠度曲线、轴压承载力及型钢、钢筋、混凝土的应变分布变化,并对试验结果和规范计算结果进行了对比。结果表明:加固后组合柱的承载力、稳定性较单独钢柱均有所提高;加载至最大荷载的75%,试验柱控制截面均满足平截面假定;加固后钢-混凝土组合试件的承载力随着初始应力水平指标的增大而减小;相同负载状态下,随着混凝土强度或配箍率的提高,加固柱承载能力和刚度均有明显提高。
In order to study the mechanical properties and the failure characteristics of steel columns under load, the axial compression tests of seven steel I-beams and one unreinforced steel column reinforced with steel-encased concrete under load were carried out. By changing the initial load size, concrete strength and stirrup ratio, the whole process and failure mode of the axial compression column before and after reinforcement were observed. The load-deflection curves of the axial compression column before and after consolidation under load were analyzed. Force and steel, steel, concrete strain distribution changes, and the test results and normative calculations were compared. The results show that the load-bearing capacity and the stability of the composite columns are higher than those of the steel columns alone. The load-bearing capacity of the composite columns increases to 75% of the maximum load. The control sections of the test columns satisfy the assumption of flat section. The force decreases with the increase of the initial stress level index. Under the same load condition, the load-bearing capacity and stiffness of the reinforced column increase obviously with the increase of concrete strength or stirrup ratio.