Tension stress in steel-concrete composite is widely observed in engineering design. Based on an experimental program on tension performance of three square concrete-filled tubes (SCFT), the tension theory of SCFT is proposed using a mechanics-based approach. The tension stiffening effect, the confining strengthening effect and the confining stiffening effect, observed in tests of SCFTs are included in the developed tension theory model. Subsequently, simplified constitutive models of steel and concrete are proposed for the axial tension performance of SCFT. Based on the MSC.MARC software, a special fiber beam-column element is proposed to include the confining effect of SCFTs under tension and verified. The proposed analytical theory, effective formulas, and equivalent constitutive laws are extensively verified against three available tests reported in the literature on both global level (e.g., load-displacement curves) and strain level. The experimental verification proves the accuracy of the proposed theory and formulations in simulating the performance of SCFT members under tension with the capability to accurately predict the tensile strength and stiffness enhancements and realistically simulate the fractal cracking phenomenon.

钢-混凝土复合材料中的拉应力在工程设计中被广泛观察到。基于三个方形填充混凝土管 (SCFT) 拉伸性能的实验程序，使用基于力学的方法提出了 SCFT 的拉伸理论。在 SCFT 测试中观察到的拉伸硬化效应、约束强化效应和约束硬化效应都包含在开发的张力理论模型中。随后，针对 SCFT 的轴向拉伸性能，提出了钢筋和混凝土的简化本构模型。基于MSC.MARC软件，提出了一种特殊的纤维梁柱单元来包含SCFTs在张力下的围压效应并进行验证。提出的分析理论、有效公式、和等效的本构定律根据文献中报告的三个可用测试在全局水平（例如，载荷-位移曲线）和应变水平上得到了广泛验证。实验验证证明了所提出的理论和公式在模拟 SCFT 构件受拉性能方面的准确性，能够准确预测抗拉强度和刚度增强，并真实地模拟分形开裂现象。