负载下外包钢筋混凝土加固钢柱轴压性能试验研究

Experimental study of axial compression behavior on steel columns strengthened by enclosed reinforced concrete under load

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 mechanism of force and failure patterns of axially loaded steel columns strengthened by enclosed reinforced concrete( SRHC) while under load,seven reinforced steel columns and an un-reinforced steel columns were designed,and three parameters were considered,which were the initial load magnitude,the concrete strength and volumetric percentage of stirrups. Failure patterns,load-deflection curve of the composite column,strain performance of steel,steel rebar and concrete were analyzed. The bearing capacity was obtained. In addition,the test results were compared with the theoretical results calculated by codes. The results show that the SRHC columns have better stability and bearing behavior than the steel columns. From the start of loading to 75% of ultimate load,the control section of specimen can meet the plane section assumption. The bearing capacity increases with the increase of the concrete strength or the volumetric percentage of stirrups,but decreases with the increase of the initial load magnitude.