Abstract: To optimize the design parameters of the steel shell-concrete composite pylon (SSCCP) section, an ideal matching relationship between steel shell and concrete was proposed for the composite pylon without longitudinal reinforcement, which was based on the principle of fully utilizing materials. The analytical expression of the ideal matching relation was derived through sectional strain distribution and axial force equilibrium. Considering the compound confinement effect provided by stiffeners and hook bars, a confinement model for the core concrete of the pylon was established, and the design strain of concrete was defined as the constrained peak strain. Parametric analysis reveals that the ideal steel ratio increases linearly with concrete strength, confinement effect, and axial compression ratio. When the axial compression ratio increases from 0.05 to 0.25, the required minimum confinement strength ratio rises from 1.00 to 1.50. Based on this matching relation, formulas for calculating the yield moment and ultimate moment of the section were derived. Compared with finite element results, the error for the ultimate moment was within 2%, and the error for the yield moment was within 8%. It is recommended in the design to achieve material matching under a high steel ratio by enhancing the concrete strength or strengthening the confinement effect, and to keep the axial compression ratio within 0.20 to ensure the ductility of the section.

Key words: bridge engineering; steel-concrete composite structure; finite element analysis; composite pylon; bearing capacity

摘要： 为了优化钢壳-混凝土组合索塔截面设计参数，针对无纵筋组合索塔，基于材料充分利用原则，提出了钢壳-混凝土的理想匹配关系。通过截面应变分布与轴力平衡，推导出理想匹配关系的解析表达式。考虑加劲肋和钩筋的复合约束效应，建立了索塔核心混凝土的约束模型，明确了混凝土设计应变为约束峰值应变。参数分析表明：理想含钢率随混凝土强度、约束效应及轴压比的增大而线性增加；当轴压比由0.05增至0.25时，所需最小约束强度比从1.00提高至1.50。基于该匹配关系，推导出截面屈服弯矩和极限弯矩的计算公式，与有限元结果对比，极限弯矩误差小于2%，屈服弯矩误差小于8%。设计中建议通过提高混凝土强度或增强约束效应来实现高含钢率下的材料匹配，并将轴压比控制在0.20以内以保障截面延性。

关键词: 桥梁工程；钢混组合结构；有限元分析；组合索塔；承载力