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高速铁路桥梁对于徐变上拱度有着严格的限制。二次预应力组合梁结构既可以满足受力要求又可以减少徐变上拱,是一种值得推广应用的新型预应力结构。二次预应力组合梁由于施工工艺的原因,两期混凝土的恒载应力和龄期不同,徐变变形相互约束导致结合面上存在徐变引起的应力。用随龄期调整的弹性模量代替混凝土弹性模量,采用三角级数描述结合面应力,通过最小余能原理考虑结合面上的变形协调求得结合面徐变应力。由一个具体算例得到矩形截面二次预应力组合梁结合面徐变应力的分布形式,可为结合面抗剪设计提供参考。
High-speed railway bridges have strict limits on creep camber. The secondary prestressed composite beam structure can not only meet the requirements of stress but also reduce the creep upper arch, which is a new type of prestressed structure that is worth popularizing and applying. Due to the construction process reasons, the second-stage prestressed composite beams have different permanent load stress and age, and the creep deformation restrains each other and leads to the stress caused by creep on the joint surface. The modulus of elasticity of concrete is replaced by the modulus of elasticity adjusted with age. The triangular surface series is used to describe the joint surface stress and the minimum residual energy principle is used to calculate the surface creep stress. The distribution form of creep stress on the joint surface of rectangular prestressed composite beam with rectangular section obtained by a concrete example can provide reference for the shear resistance design of combined surface.