设置钢筋加劲肋薄壁方钢管混凝土短柱试验研究

Experimental research on concrete-filled square thin-walled steel tubular stub columns with steel bar stiffeners

对设置钢筋加劲肋薄壁方钢管混凝土短柱的受力性能进行了试验研究,分析了管壁内侧设钢筋加劲肋、管壁外侧设钢筋加劲肋、内置钢筋笼和加劲肋刚度对薄壁方钢管混凝土短柱的破坏特征、受力性能及破坏机理的影响,以及不同钢筋加劲肋形式对方钢管混凝土短柱静力性能的改善效果。试验结果表明,薄壁空钢管柱的承载力较低,仅为其名义承载力的37.7%,钢材未达到屈服强度,管壁就已经发生局部屈曲,钢材性能未得到充分发挥;相对于空钢管柱,钢管混凝土柱的承载力和延性得到显著的提高,但由于钢管截面宽厚比较大,管壁局部屈曲发生较早,极限承载力仍小于名义承载力,钢管对核心混凝土的约束作用不明显。钢筋加劲肋的设置可以有效延缓钢管壁局部屈曲,大幅提高薄壁方钢管混凝土柱的极限轴压承载力。在钢管混凝土柱内设置钢筋笼,可以提高其极限承载力,但不能延缓钢管局部屈曲的发生。

To understand mechanical characteristics of concrete-filled thin-walled steel tubular with steel bar stiffeners,monotonic loading tests were carried out.The influence of inside steel bar stiffeners,outside steel bar stiffeners,the inner reinforcing bar cage and the stiffness of stiffeners were investigated,which determine the failure characteristic,mechanical behavior and failure mechanism.The effect of stiffener's shape was also considered.In the experiment,local buckling of tube wall occurred prior to steel yielding due to the big width-thickness ratio,resulting in the bearing capacity of thin-walled steel tubular stub columns being only 37.7% of its nominal capacity.Compared with thin-walled steel tubular,the bearing capacity and ductility of concrete-filled square thin-walled steel tubular stub columns is greatly improved but is still smaller than the nominal capacity because of the early buckling of steel tube.Steel bar stiffeners can effectively delay the local buckling of steel tube wall and improve the ultimate axial bearing capacity.The inner reinforcing bar cage can improve the ultimate axial bearing capacity but can not delay local buckling.