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在实腹钢梁或钢桁架下部张拉预应力高强钢索形成预应力张弦梁结构,然而钢索的预应力对温度变化敏感,因此火灾是危及张弦梁结构安全性的重要灾害,求解高温下结构的力学特征解析解是进一步研究其火灾安全性能的理论基础。考虑高温下钢材材性的衰减、非线性热应变以及几何形变的耦合,建立张弦梁结构高温下梁单元与索单元建立基本平衡微分方程,分别推导出在均布荷载作用下张弦梁结构在均匀温度场及非均匀温度场中,结构跨中挠度、预应力索水平张力和撑杆轴力的解析解;并且基于张弦梁结构力学特征解析解,对比分析了张弦梁结构热力耦合数值分析模型的可靠性,可为后继设计张弦梁受火试验方案及研究其受火破坏机理提供参考。
However, the prestress of the cable is sensitive to the temperature change. Therefore, the fire is an important disaster that endangers the structural safety of the beam string girder and solves the structural problems of high temperature structure Analytical solution of mechanical characteristics is to further study the fire safety performance of the theoretical basis. Considering the decay of steel material, the nonlinear thermal strain and the coupling of geometric deformation under high temperature, the basic equilibrium differential equation of beam element and cable element is established under the action of uniform load. And the non-uniform temperature field, the structural mid-span deflection, the horizontal tension of the prestressed cable and the axial force of the brace were analyzed. Based on the analytical solution of the mechanical characteristics of the beam string structure, the reliability of the thermo-mechanical coupled numerical analysis model for the beam string structure was compared and analyzed. It provides a reference for the succession design of the beam string fire test program and its fire destruction mechanism.