方形钢管和钢管混凝土的性能研究

对方钢管和钢管混凝土的局部屈曲进行研究，主要分析不同的深厚比对钢构件的影响。通过对24个深厚比数值为50～125的构件进行试验发现，混凝土的存在会影响已有的屈曲模式，并显著增加钢管混凝土的屈曲承载力。采用ABAQUS软件建立数值模型，并与试验结果进行有效对比。从设计角度来看，当构件深厚比高于50时，计算钢构件对钢管混凝土承载力贡献的同时应包含局部屈曲效应。例如，对深厚比超过120的细长板，其后屈曲效应能明显增加其承载能力，所以在计算钢构件对承载能力的贡献时应考虑这一效应。最后，提出计算包括短粗和细长钢结构复合截面的承载力计算公式，并通过了大量试验结果的验证。

Behavior of Square Hollow Steel Tubes and Steel Tubes Filled with Concrete

This paper investigates the occurrence of local buckling in bare steel and concrete-filled tubes to study how different depth-to-thickness ratios affect the response of the steel component. The experimental set-up and results of 24 tests are presented in this paper. Specimens with values of depth-to-thickness ratios in the range of 50–125 have been considered. The presence of the concrete has been observed to affect the exhibited buckling mode and to significantly increase the buckling bearing capacity of the concrete-filled steel tubes. A numerical model has been developed using the commercial software ABAQUS and has been validated against the experimental results of this study. From a design viewpoint, it has been observed that local buckling needs to be included in the calculation of the contribution of the steel component to the bearing capacity of a concrete-filled tube when its depth-to-thickness ratio is over 50. For a slender plate, i.e., with a depth-to-thickness ratio over 120, its post-buckling behavior could be included in the calculation of the steel contribution as it evidently increases its bearing capacity. Finally, an equation for the calculation of the bearing capacity of composite sections with both stocky and slender steel elements has been proposed and validated against extensive experimental results available in the literature.