“板—桁模型”计算预应力混凝土复合受力构件抗扭强度

弯、剪、扭复合受力下混凝土构件的受力特性非常复杂,准确计算构件的抗扭强度对构件的设计及工作性能的分析都非常重要。在钢筋混凝土构件的板-桁模型理论基础上,以预应力混凝土构件在复合受力下的板—桁模型理论为基础,以箱形截面预应力混凝土构件为例,由力及力矩的平衡、变形关系、材料本构关系及构件的破坏准则,建立了在小扭弯比情况下复合受力构件抗扭承载力的计算方法。所建立的计算模型及公式理论基础强、概念清晰,经试验值与理论计算值对比,符合情况较好,证实了板—桁模型理论分析复合受力构件抗扭性能的正确性。

THE CALCULATION OF TORSIONAL STRENGTH OF PRE-STRESSED CONCRETE MEMBERS UNDER COMBINED FORCES BASED ON PLATE-TRUSS MODEL

The mechanical characteristics of pre-stressed concrete beams under combined forces of bending, shear and torsion are complicated. Accurate calculations for the purpose of the structural design and functional analysis require precise knowledge of the torsional strength of each concrete structural member. This paper proposes a formula to calculate the torsional strength of structural members under conditions of small torsion-bending ratio, using the plate-truss model of pre-stressed concrete beams under combined forces of bending, shear and torsion. The calculations focus on the case of the pre-stressed concrete box-section beam. These calculations are based on the equilibrium conditions of forces and moment, and the deformation and constitutive relationships, as well as the failure criteria of the materials. Results agree well with experimental data. Therefore, the plate-truss model theory of pre-stressed concrete beams under combined forces is verifyied.