Abstract Nowadays concrete-filled steel tubes (CFTs) are used in many types of structures. In spite of significant advances, the application of this system has not widely adopted in marine structures. While due to the presence of hydrostatic pressure on the body of the tube, outward buckling, which may be considered as one of the weaknesses of the system, could be delayed. Therefore, theoretical and experimental studies were performed to investigate the effects of external pressure on the compressive behavior of circular concrete-filled steel tubes. In this paper, CFT columns with three different diameter-to-thickness (D/t) ratios of 50, 100 and 200 filled with three concrete compressive strength grades of 15, 30 and 45 MPa. The external pressure and axial load were applied to the specimens simultaneously by tri-axial testing set up designed and constructed by the authors. Based on the test results, the external pressure can effectively increase the load-carrying capacity, as well as the ductility of the specimens. Minimum and maximum improvement in ultimate strength were 67% and 308% respectively. Generally effect of external pressure on specimen filled with lower concrete strength was more than others. Finally, a nonlinear finite element (FE) numerical model using the commercial software package ABAQUS is also developed to predict the performance of such columns. The results show that the proposed FE numerical model provides good agreement with experimental data.

中文翻译：

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外压对钢管混凝土短柱抗压性能影响的试验与分析研究

摘要 如今，钢管混凝土（CFTs）被用于多种类型的结构中。尽管取得了重大进展，但该系统的应用尚未广泛应用于海洋结构中。而由于管体上存在静水压力，可能被认为是系统弱点之一的向外屈曲可能会延迟。因此，进行了理论和实验研究，以研究外部压力对圆形钢管混凝土压缩行为的影响。在本文中，具有 50、100 和 200 三种不同直径与厚度 (D/t) 比的 CFT 柱填充了三个混凝土抗压强度等级 15、30 和 45 MPa。外压和轴向载荷通过作者设计和建造的三轴试验装置同时施加到试件上。根据试验结果，外压可有效提高试件的承载能力和延展性。极限强度的最小和最大改进分别为 67% 和 308%。一般外压对低强度混凝土填充试件的影响大于其他试件。最后，还开发了使用商业软件包 ABAQUS 的非线性有限元 (FE) 数值模型来预测此类柱的性能。结果表明，所提出的有限元数值模型与实验数据具有良好的一致性。外压能有效提高试件的承载能力和延展性。极限强度的最小和最大改进分别为 67% 和 308%。一般外压对低强度混凝土填充试件的影响大于其他试件。最后，还开发了使用商业软件包 ABAQUS 的非线性有限元 (FE) 数值模型来预测此类柱的性能。结果表明，所提出的有限元数值模型与实验数据具有良好的一致性。外压能有效提高试件的承载能力和延展性。极限强度的最小和最大改进分别为 67% 和 308%。一般外压对低强度混凝土填充试件的影响大于其他试件。最后，还开发了使用商业软件包 ABAQUS 的非线性有限元 (FE) 数值模型来预测此类柱的性能。结果表明，所提出的有限元数值模型与实验数据具有良好的一致性。还开发了使用商业软件包 ABAQUS 的非线性有限元 (FE) 数值模型来预测此类柱的性能。结果表明，所提出的有限元数值模型与实验数据具有良好的一致性。还开发了使用商业软件包 ABAQUS 的非线性有限元 (FE) 数值模型来预测此类柱的性能。结果表明，所提出的有限元数值模型与实验数据具有良好的一致性。