钢管混凝土叠合柱偏心受压性能试验研究

对长细比为4.67的13个钢管混凝土叠合柱试件进行偏心受压试验，测试柱承载至破坏全过程中核心钢管、管内混凝土、管外混凝土以及管外纵筋的应力、应变分布规律，研究试件的承载机理和破坏特征，同时结合截面非线性数值分析，研究柱正截面承载力随偏心距、钢管位置系数、纵筋配筋率等参数变化的规律。结果表明：偏心受压钢管混凝土叠合短柱正截面的受力过程与钢筋混凝土短柱基本相似，破坏类型分为大偏心受压破坏，小偏心受压破坏和界限破坏3种，以受拉钢筋屈服，同时受压边缘混凝土达到极限压应变为界限破坏准则，其N-M相关曲线为二次抛物线；叠合柱横截面应变符合平截面分布，不论偏心距大小，受压钢筋屈服总是先于受压区混凝土压碎；叠合柱承载力随钢管位置系数的增大而增加，但增幅不大，故在保证叠合柱含钢率不变条件下，可以梁柱节点施工便利为主选择钢管直径；对于钢管混凝土叠合柱可参照钢筋混凝土结构采用截面极限平衡理论推导叠合柱的偏压承载力计算公式。

Experimental study on eccentric compressive property of steel tube-reinforced concrete columns

Eccentric loading experiments of 13 steel tube-reinforced concrete columns (STRC), whose slenderness ratio was 4.67, were completed. Through testing the distribution of strain and stress of every part (including core steel pipes, concrete inside and outside of pipes, longitudinal reinforcements) in the whole loading process, the bearing mechanism and failure feature of STRC were studied. Furthermore, using numerical nonlinear analysis, the influences of position coefficient, eccentricity and longitudinal reinforcement ratio upon bearing capacity were obtained. The study shows following conclusions. STRC columns subjected to eccentric compression are similar to reinforced concrete columns (RC), and the failure types are divided into large eccentric failure, small eccentric failure and limitation failure where the demarcation criterion is that the edge strain of concrete compression reaches the ultimate compressive strain as soon as the tensile steel yields. And its N-M curve is parabolic. STRC adheres to plane cross section assumption and its compressive reinforcements can always yield before the columns’ failure without reference to its eccentricity. The bearing capacity of STRC is enhanced with the increase of position coefficient, but not by much, so the steel pipe can be selected only by considering its cross-sectional area and for the convenience of joints construction. Based on the test results, limit equilibrium theory can be used to deduce the normal section capacity formula of STRC columns by referring to that for RC columns.