Due to the presence of composite action between steel and concrete, applications of concrete-filled tubular structures have increased rapidly in bridges, high-rise buildings and other infrastructures. In this study, a total of 15 square concrete-filled welded cold-formed steel columns were tested under concentric loading. Failure modes, ultimate strength and ductility of test specimens were analyzed on several parameters, including concrete compressive strength (f^′_c  = 27, 35 and 44 MPa), cross-sectional slenderness ratio (B/t = 25, 31 and 42) and global slenderness ratio (L/B = 3, 5 and 10). The results show that increasing the concrete compressive strength improved the ultimate strength, but decreased ductility of the test specimens. On the other hand, columns with higher slenderness ratio (B/t or L/B) showed lower ultimate strength and less ductile behavior. Failure appearances of the test columns include: outward buckling of the steel tube, crushing of in-fill concrete and welding failure at the joint. Meanwhile, no cracks were found at the corners of the test specimens due to the use of round corner cold-formed built-up steel sections. Finally, the design approaches adopted in (Eurocode-4, AISC-360-10 and Wang et al. 2017) are compared with the ultimate strength of the test columns, which shows satisfactory agreement between the predicted and experimental capacities.

由于钢和混凝土之间存在复合作用，因此在桥梁，高层建筑和其他基础设施中，混凝土填充管状结构的应用迅速增加。在这项研究中，在同心荷载下总共测试了15个方形混凝土填充焊接冷弯型钢柱。故障模式，极限强度和测试样品的延展性于几个参数，包括混凝土的抗压强度（分析˚F ^' _Ç  = 27，35和44兆帕），横截面的长细比（乙/吨 = 25，31和42）和全球纤细比（L / B = 3、5和10）。结果表明，提高混凝土的抗压强度可以提高极限强度，但会降低试样的延展性。另一方面，细长比更高的列（B / t或L / B）显示出较低的极限强度和较少的延展性。测试柱的失效外观包括：钢管的向外弯曲，填充混凝土的压碎和接头处的焊接失效。同时，由于使用了圆角冷成型的组合钢型材，因此在试样的角部没有发现裂纹。最后，将（Eurocode-4，AISC-360-10和Wang等人2017）中采用的设计方法与测试柱的极限强度进行了比较，这显示了预测能力与实验能力之间的令人满意的一致性。