Structural System Selection for Steel-Concrete Composite Girder Bridges of Shiziyang Link

The Shiziyang Link, totaling 35 km, is a double-deck river crossing that accommodates highways and urban roadways. Of which, the section over the pearl river consists of double-deck bridges where the upper decks carry highways and the lower decks bear urban roadways. Multiple main line bridges contain spans of 50 to 80 m long, fitted with steel-concrete composite main girders. The simply-supported and continuous types of bridges were compared, and a simply-supported structure with continuous deck system, featuring hidden cap beams, was finally selected. Five composite girder types were compared, including the composite girder with I steel plates and concrete slabs, the composite girder with integral steel box girders and concrete slabs, the composite girder with corrugated steel webs, the composite girder with steel truss webs and the composite girder with split small box girders and concrete slabs, and the composite girder with split small box girders and concrete slabs was finally chosen. To make a better balance between various factors, including the load bearing performance of the structure, economy, ease-of-construction, transportation access and adaptation to width-varying sections, it was determined to adopt four small steel box girders along bridge width, which would facilitate the standardized design, manufacture, and construction, allow the load bearing performance of the bridge to be more rational and greatly reduce the engineering costs. Considering the construction space, facilities available, construction schedule and safety, the steel components were manufactured with stipulated standards, concrete slabs were prefabricated in the factory, and the steel girders and the concrete slabs were assembled to be composite girders via cast-in-situ stitches, concentrated prestressing tendons and shear studs. © 2023 Wuhan Bridge Research Institute. All rights reserved.