既有铆接钢桁梁桥拓宽改建时的主桁构件加固设计

为针对原位拓宽的铆接钢桁架桥中不同受力特点的桁架构件采用合理的加固方法,以松浦大桥拓宽加固工程为例进行分析。松浦大桥主桥上部结构采用两联(96+112)m的连续铆接钢桁梁,根据拓宽后的结构荷载,按照现行规范计算确定承载力不足的主桁构件,并根据这些构件的受力特点分3类进行加固。对抗拉强度不足的构件,采用在其翼缘或腹板增贴钢板的方法进行加固;对稳定不足的构件,采用增贴角钢的方法进行加固,此外,可增设侧向约束构件以减小杆件的计算长度;对抗压强度与稳定均不足的构件,采用填筑混凝土形成组合构件的方法进行加固。按照所提出的方法对松浦大桥主桁构件进行加固后,其主桁构件的承载力均能够满足现行规范要求。

Reinforcement Design of Main Truss Members of Existing Riveted Steel Truss Bridge in a Widening and Reconstruction Project

In order to adopt reasonable reinforcement methods for different truss members of the riveted steel truss bridge in in-situ reconstruction, the widening and strengthening project of the Songpu Bridge is analyzed as an example. The main bridge superstructure of the Songpu Bridge consists of two (96+112) m continuous riveted steel truss girders. Based on the load of widened structure, the main truss members with insufficient bearing capacity are determined according to current codes, and these members are reinforced in 3 categories based on their mechanical features. For members with insufficient tensile strength, steel plates are added to the flange or web. For those with insufficient stability, angle steels are added to reinforce them. In addition, lateral restraint components can be installed to reduce the effective length of compression members. Members with insufficient compressive strength and stability are reinforced by filling concrete to form composite members. The results show that the load bearing capacity of this bridge reinforced according to the proposed reinforcement methods can meet the requirements of current standards.