带约束拉杆L形钢管混凝土短柱的偏压承载力

BEARING CAPACITY OF L-SHAPE CFT STUB COLUMNS WITH BINDING BARS SUBJECTED TO ECCENTRIC COMPRESSION LOAD

在钢板中部位置设置具有约束钢板外凸变形作用的水平拉杆,是改善异形钢管混凝土柱力学性能的有效方法。该文介绍了8个带约束拉杆L形钢管混凝土偏压短柱试件的试验,结果表明约束拉杆的设置延迟钢管局部屈曲的发生,有助于L形钢管混凝土偏压短柱承载力的提高;偏心受压下该柱的截面应变符合平截面假定。采用带约束拉杆L形钢管的管内核心混凝土本构关系,利用纤维模型法对试件偏压极限承载力进行数值计算,计算结果与试验结果吻合良好。利用该数值方法对带约束拉杆L形钢管混凝土偏压短柱进行参数研究,分析了钢材屈服强度、截面含钢率、混凝土强度、拉杆约束系数及荷载角对N/Nu-M/Mu曲线的影响规律,在此基础上提出带约束拉杆L形钢管混凝土偏压短柱双向压弯承载力的简化计算公式。

It is an effective method to improve the mechanical behavior of special-shape concrete-filled steel tubular columns by setting binding bars in the middle position of steel plates which constrain outer convex of the steel plate. A total of 8 L-shape concrete-filled steel tubular （L-CFT） stub columns with binding bars subjected to eccentric compression were tested. The test results demonstrate that the local buckling of the steel plates is delayed and the bearing capacity and ductility of eccentric-loaded specimens are improved by setting the binding bars. The assumption that plane section remains plane is also proved for the specimens. The fiber model was applied to predicting the bearing capacity of the specimens, where the concrete is assumed to follow the constitutive relationship of L-CFT with binding bars. The predicted results agree well with experimental ones. An extensive parameter study is conducted to investigate the effects of steel yield strength, sectional steel ratio, concrete cube strength, constraining factor of binding bars and load angles on N/Nu —M/Mu curves. A simplified method is put forward to predict the bearing capacity under biaxial bending .