复式薄壁方钢管混凝土柱的偏压力学性能研究

进行了9根带纵向加劲肋的复式薄壁方钢管混凝土柱的偏压试验.试验结果表明构件的承载力随着偏心距和长细比的增大而下降,但随着核心混凝土强度的提高而提高.基于充分验证的有限元模型,研究复式薄壁方钢管混凝土偏压柱的工作机理,并进行大量的参数分析.研究表明:外钢管的约束主要集中在角部,混凝土承担了大部分荷载,填充核心混凝土可改善组合构件的延性.钢材屈服强度、内钢管混凝土含钢率和径宽比越大,相对轴力-相对弯矩相关曲线的平衡点的横、纵坐标越小;但是随着混凝土强度的增大,相关曲线的平衡点的横、纵坐标均有增大的趋势;随着长细比的增大,轴力-弯矩相关曲线趋近于直线.最终建议了复式薄壁方钢管混凝土偏压柱的承载力简化计算式.

Study on Behaviour of Composite Concrete-filled Square Thin-walled Steel Tubular Columns under Eccentrical Compression

The tests of 9 composite concrete-filled square thin-walled steel tubular (CCFSTST) columns with longitudinal stiffeners under eccentric compression were carried out. The test results indicated that the load-carrying capacity decreased with the increase of eccentricity and slenderness ratio, but increased with the increase of core concrete strength. Based on the finite element model verified by the test results, the working mechanism of CCFSTST columns was studied and the parametric analysis was conducted. It can be found that the confinement of the outer steel tube is focused on the corners of the cross-section, the majority of the load is resisted by the concrete and the ductility of the composite column is enhanced by filling core concrete. With the increase of the steel yield strength, steel ratio of inner concrete-filled steel tube and diameter to width ratio, the abscissa and ordinate values of the equilibrium point in the relative axial compression versus relative moment relationship decreased, but they increased with the increase of concrete strength. Meanwhile, with the increase of slenderness ratio, the axial compression versus moment relationship trended to be a straight line. Finally, the simplified model was proposed to predict the load-carrying capacity of CCFSTST columns under the eccentric compression.