A new variation of fibre-reinforced polymer (FRP) confined concrete-steel double-skin tubular column (DSTC) shows more promise than its traditional form when steel stiffeners are provided on the inner steel tube. Stiffeners can provide better composite action between individual DSTC components, reduce local buckling, and potentially improve confined concrete behavior. The present study performs the first-ever experimental and analytical investigation to quantify the influence of stiffened steel tube on the confined concrete behavior of square-shaped DSTCs. First, a total of 18 DSTC specimens were tested by varying the steel stiffener properties, such as quantity, configuration for the similar total stiffener-rib area, effective placement, and rib cross-section dimensions and shape. Providing stiffened steel tubes in DSTCs showed a significant increase in axial load capacity (up to about 52% in this study) with enhanced ductility than unstiffened specimens. Then the test results were used to propose an analysis-based confined concrete model for square-shaped stiffened DSTCs. Detailed finite element analyses were performed for validation study using the proposed concrete model. The numerical results showed excellent agreement with tests (about 2–4% average errors at critical elastic, peak and ultimate axial loads) and captured well both the elastic and inelastic compressive behavior of stiffened DSTCs. Finally, this study proposed a simple analytical equation for accurately estimating the peak axial load-bearing capacity of square-shaped stiffened DSTCs.

当在内钢管上提供钢加强筋时，纤维增强聚合物 (FRP) 约束混凝土-钢双皮管柱 (DSTC) 的新变体比其传统形式显示出更多的希望。加强筋可以在单个 DSTC 组件之间提供更好的复合作用，减少局部屈曲，并有可能改善受限混凝土的行为。本研究首次进行了实验和分析研究，以量化加筋钢管对方形 DSTC 的受限混凝土行为的影响。首先，通过改变钢加强筋性能，例如数量、相似的加强筋肋总面积的配置、有效布置以及加强筋横截面尺寸和形状，总共对 18 个 DSTC 试样进行了测试。在 DSTC 中提供加筋钢管显示轴向载荷能力显着增加（在本研究中高达约 52%），与未加筋试样相比具有增强的延展性。然后根据测试结果提出了一种基于分析的方形加筋 DSTC 约束混凝土模型。使用建议的混凝土模型进行了详细的有限元分析以进行验证研究。数值结果显示与测试非常吻合（在临界弹性、峰值和极限轴向载荷下平均误差约为 2-4%），并且很好地捕捉了加筋 DSTC 的弹性和非弹性压缩行为。最后，本研究提出了一个简单的解析方程，用于准确估计方形加筋 DSTC 的峰值轴向承载能力。