不同预制方式下大跨度组合梁桥受力性能分析

为了明确整体预制大跨度π形钢混组合梁与分离预制组合梁的受力性能，结合实际工程，采用板壳-实体有限元方法，计算了两种大跨度组合梁受力性能。计算结果表明：在成桥阶段整体预制组合梁的钢梁应力比分离预制组合梁的小很多，两种组合梁钢梁上缘的最大压应力分别为84.3 MPa和229.0 MPa，下缘的拉应力分别为167.3 MPa和196.0 MPa，两种组合梁中支点处混凝土上缘应力基本相同。钢梁在成桥十年时，两种组合梁钢梁上缘的最大拉应力增量分别为88.1 MPa和-4.0 MPa。整体预制组合梁的混凝土最大拉应力为分离预制组合梁的0.67倍。另外，在施工效率和施工质量方面，山区建造大跨度组合梁桥采用整体预制方式具有明显的优势。

Analysis on Mechanical Performance of Long-span Composite Girder Bridge under Different Prefabricated Methods

In order to clarify the mechanical performances of integral prefabricated long-span π-type steel and concrete composite girder and separated prefabricated girder, combined with an actual project, the shell-entity finite element method is used to calculate the mechanical performances of two types of large-span composite girders. The results of the calculations show that the stresses in the integrated prefabricated composite girders are much less than those in the separated prefabricated composite girders during the bridge finishing stage. The maximum compressive stresses at the upper flange of the steel girders of two composite girder are 84.3 MPa and 229.0 MPa respectively, and the tensile stresses at the lower flange are 167.3 MPa and 196.0 MPa respectively. The stresses at the upper flange of the concrete at the middle support position of the two composite girders are almost the same. At 10 years of completion, the maximum tension stress increment at the upper flange of steel girder of the two composite girder are 88.1 MPa and -4.0 MPa respectively. The maximum tension stress of concrete of the integrated prefabricated composite girder is 0.67 times of the separated prefabricated composite girder. In addition, from the aspects of construction efficiency and construction quality, the integrated prefabrication method has obvious advantages in the construction of long-span composite girder bridges in mountainous areas.