公路工程

为提高组合梁负弯矩区桥面板抗裂性能，提高结构耐久性，提出一种钢-UHPC-NC组合梁结构形式，即在传统钢混组合梁的基础上，负弯矩区域采用薄层超高性能混凝土(UHPC)替代部分普通混凝土(NC)。以主跨80 m钢混组合梁桥为背景，介绍了钢-UHPC-NC组合梁的构造特征，并借助有限元软件对该桥梁进行结构计算，重点分析了钢梁和桥面板在施工阶段和运营阶段的受力性能，结果表明：(1)钢梁在施工阶段和运营阶段各部位应力均小于钢材强度设计值，结构受力安全；(2)桥面板采用UHPC的区段最大拉应力为4.58 MPa,小于UHPC轴心抗拉强度设计值5.2 MPa;桥面板采用普通混凝土的区段最大裂缝宽度为0.07 mm,小于规范限值0.20 mm。

In order to improve the crack resistance of the bridge deck in the negative bending moment area of the composite beam and improve the structural durability, this paper proposes a steel-UHPC-NC composite beam structure, that is, on the basis of the traditional steel-concrete composite beam, the negative bending moment area is thin Layer Ultra High Performance Concrete(UHPC) replaces part of ordinary concrete(NC).Taking a steel-concrete composite girder bridge with a main span of 80 m as the background, the structural characteristics of the steel-UHPC-NC composite girder are introduced, and the structure calculation of the bridge is carried out with the help of finite element software, focusing on the analysis of the construction and operation of the steel girder and bridge deck the mechanical performance of the stage, the results show:(1)The stress of each part of the steel beam during the construction and operation phases is less than the design value of the steel strength, and the structure is safe;(2)The maximum tensile stress of the UHPC section of the bridge deck is 4.58 MPa, which is less than the UHPC axial tensile strength design value of 5.2 MPa; the maximum crack width of the bridge deck using ordinary concrete is 0.07 mm, which is less than the specification limit of 0.20 mm.