矩形截面二次预应力组合梁结合面徐变应力分析

CREEP STRESS ON THE CONTACT SURFACE OF TWICE-PRESTRSSED COMPOSITE BEAM WITH RECTANGULAR SECTION

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。

The creep camber of a high-speed railway bridge should be carefully considered.In the case of satisfying the mechanical performance,a twice-prestressed composite beam has the advantages of reducing the creep camber and is worth popularizing.Due to different construction technology,the dead-load stresses and concrete ages of two periods are different.Creep deformations have restraints on each other,which causes a stress on the contact surface.This paper adopts an age-adjusted effective modulus instead of modulus of concrete,and uses trigonometric progression to describe the stress on the contact surface to get the stress by the minimum excess principle based on deformation compatibility.The distribution of the stress obtained from a material example,which can provide references for the shear resistance design of the contact surface.