钢-混凝土组合梁负弯矩区畸变稳定性研究

The study of distortional stability of steel-concrete composite beams in negative moment zone is still in its early stage, while some key issues haven’t been well addressed. First of all, this project will be focused on the distortional stability test of steel-concrete composite beams in negative moment zone. The finite element numerical simulation model considering the residual stress and initial geometric imperfection will be established. Then the bending-torsional distortional instability mode and failure mechanism under complex loads will be explored. Furthermore, the rotational and lateral restraint stiffness mathematical model considering the coupling between external load and rigidity will be proposed, and the traditional variable axial force elastic foundation beam method will be improved on the basis of considering the finite deformation before buckling and coupling between external load and rigidity of bottom flange. As a result, a formula suitable for steel-concrete composite beams will be derived for practical calculation of distortional buckling critical load in the project. Also, the influence factors and the corresponding influence rules on ultimate bearing capacity of steel-concrete composite beams in negative moment zone will be investigated, which will be employed for developing a reduction factor computational formula. Finally, the practical calculation stability curve ultimate bearing capacity of steel-concrete composite beams in negative moment zone will be established. The research results will further provide theoretical foundation and technical support for engineering application of composite beam structure.

目前国内外对钢-混凝土组合梁负弯矩区畸变稳定性方面的研究尚不成熟，诸多关键科学问题亟待解决。本项目将开展钢-混凝土组合梁负弯矩区稳定性能试验，建立考虑残余应力和初始几何缺陷的弹塑性有限元数值仿真模型，探索复杂受力情况下钢-混凝土组合梁的畸变屈曲模态及失效模式。提出考虑外荷载-刚度耦合关系的下翼缘转动约束刚度及侧向约束刚度计算模型，在考虑外荷载-下翼缘刚度耦合关系和屈曲前有限变形影响基础上，对传统的变轴力弹性地基梁法进行改进，推导适合变轴力情况的钢-混凝土组合梁负弯矩区畸变屈曲临界荷载实用计算公式。考察钢-混凝土组合梁负弯矩区极限承载力的影响因素及其影响规律，提出相应的折减系数计算公式，最终建立钢-混凝土组合梁负弯矩区极限承载力实用计算稳定曲线。研究成果将进一步为钢-混凝土组合梁结构在实际工程中的应用提供理论依据和技术支持。

本项目建立了考虑残余应力和初始几何缺陷的弹塑性分析模型，探索了复杂受力情况下钢-混凝土组合梁的畸变屈曲模态及失效模式。提出了考虑外荷载-刚度耦合关系的下翼缘转动约束刚度及侧向约束刚度计算模型，在考虑外荷载-下翼缘刚度耦合关系和屈曲前有限变形影响基础上，对传统的变轴力弹性地基梁法进行改进，推导了适合变轴力情况的钢-混凝土组合梁负弯矩区畸变屈曲临界荷载实用计算公式。考察钢-混凝土组合梁负弯矩区极限承载力的影响因素及其影响规律，提出相应的折减系数计算公式，最终建立钢-混凝土组合梁负弯矩区极限承载力实用计算稳定曲线。研究成果将进一步为钢-混凝土组合梁结构在实际工程中的应用提供理论依据和技术支持。课题研究期间，发表论文17篇，其中SCI收录13篇,EI收录3篇，协助培养博士研究生2名，硕士研究生3名。

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