宜宾盐坪坝长江大桥为主跨480 m的混合梁斜拉桥, 中跨为钢混组合梁、边跨为预应力混凝土梁, 钢混结合段设置在索塔附近中跨侧10.5 m处, 中跨桥面宽度为40 m, 双向6车道.钢混组合梁由钢主纵梁、钢横梁、小纵梁、预制桥面板、现浇桥面板几部分构成.通过分析研究, 钢混组合梁采用双钢箱梁+混凝土桥面板断面型式, 外侧腹板处高度为3.5 m, 桥轴线处高度为2.9 m;节段长度为10.5 m、11.1 m, 合龙段长7 m, 钢横梁间距为3.5 m、3.7 m;混凝土桥面板厚度为26 cm, 索塔附近加厚至28 cm, 腹板附近局部加厚至40 cm;索梁锚固采用钢锚箱, 设置在钢箱梁内部.空间计算结果表明:钢主纵梁、混凝土桥面板、钢横梁的应力均控制在合理范围内;汽车荷载作用下, 主梁竖向挠度最大值为-340 mm, 刚度满足要求.%Yibin Yanpingba Changjiang River Bridge is a 480 m-span composite beam cable-stayed bridge. Its middle span is a steel-concrete composite girder. Its side span is a pre-stressed concrete beam.The steel-concrete combined section is set up at 10.5 m of the middle span side near the cable pylon. The deck of middle span is 40 m wide with double-way six lanes. The steel-concrete composite girder is composed of main steel longitudinal girder, steel cross girder, small longitudinal beam, prefabricated deck slab and cast-in-situ deck slab. According to the analysis and study, the steel-concrete composite girder adopts the section type of steel double-box girder + concrete deck slab. The height at the outside web is 3.5 m. The height at the bridge axis is 2.9 m. The segment length is 10.5 m and 11.1 m. The closure section is 7 m long. The spacing of steel cross girder is 3.5 m and 3.7 m. The thickness of concrete deck slab is 26 cm.The thickness near the cable pylon is to 28 cm and the local thickness near the web is to 40 cm. The anchorage of cable girder adopts the steel anchor box, which is set up in the steel box girder. The space calculation result shows that the stresses of main steel longitudinal girder, concrete deck slab and steel cross girder are all controlled in the reasonable range, the maximum value of vertical deflection of main girder is-340 mm and the rigidity meets the requirements.
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