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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。
Thirteen concrete filled steel tubular columns with a slenderness ratio of 4.67 were subjected to eccentric compression tests. The stress and strain distributions of the test steel pipes loaded to the core steel pipe, the concrete in the pipe, the concrete outside the pipe and the longitudinal reinforcement of the pipe were measured. , The bearing mechanism and failure characteristics of specimens were studied. Combined with the nonlinear numerical analysis of section, the regularity of bearing capacity of normal section of column with parameters such as eccentricity distance, steel pipe position coefficient and longitudinal reinforcement ratio was studied. The results show that the stress of normal section of short column of eccentric compression concrete filled steel tube is basically similar to that of reinforced concrete short column. The failure types are classified into large eccentric compression failure, small eccentric compression failure and boundary damage, The yield stress of the reinforced concrete and the ultimate compressive strain of the compacted edge concrete reach the limit failure criterion. The NM correlation curve is quadratic parabola. The cross-sectional strain of the composite column is in accordance with the distribution of the flat section. Regardless of the eccentricity, the yielding of the compacted steel always precedes The compressive strength of the concrete in the compressive zone is reduced. The bearing capacity of the composite pillars increases with the increase of the position coefficient of the steel pipe, but the increase rate is insignificant, so under the condition of keeping the steel content of the laminated pillars constant, For the concrete-filled steel tubular column, the formula of the ultimate bearing capacity of the composite column can be deduced with reference to the reinforced concrete structure using the sectional equilibrium theory.