America standard AWS D1.5 Steel Box Girder Bridge by Incremental Launching Method

Steel box girder bridge, with steel box girder as its main load-bearing structure, is a type of bridge. Its core structure is a closed or open box-section beam body composed of top plate, bottom plate, web plate, internal stiffening ribs, and diaphragms, resembling a huge hollow "box" in appearance.

Structural Features and Advantages:

    High torsional rigidity: The enclosed box-shaped cross-section provides exceptional torsional resistance, effectively resisting torques generated by vehicle eccentric loads, lateral wind loads, etc. It is particularly suitable for curved bridges and skew bridges.

    Lightweight and High Strength: Due to the lightweight and high-strength characteristics of steel, steel box girders are approximately 30% to 50% lighter than concrete girders with the same load-bearing capacity. This significantly reduces the workload of the substructure (pier, foundation), making steel box girders suitable for large-span bridges, high seismic fortification zones, or sites with poor foundation conditions.

    Low building height: With the same span, the beam height of steel box girders can be lower than that of concrete beams, which is conducive to meeting the clearance or landscape requirements under the bridge and achieving a visually "thin" yet "rigid" effect.

    Fast construction speed: Steel box girders can be prefabricated in sections in the factory and then transported to the site for rapid installation using methods such as lifting, jacking, or cantilever assembly. This process causes minimal interference to the traffic or existing facilities beneath the bridge, making it particularly suitable for projects involving urban renewal, crossing existing roads, or rivers.

    High degree of industrialization: standardized design, factory production, on-site mechanized assembly, easy quality control, and recyclable steel materials, all of which align with the concept of green construction.

Application Scenario:

    Long-span bridges: Highway and railway bridges with a main span of over 200 meters, such as river-crossing and sea-crossing bridges (commonly featuring steel main beams as composite beams).

    Urban interchange and viaduct: They are required for urban expressways with small curvature radii, crossing complex intersections, or dense underground pipelines.

    Pedestrian overpass: Lightweight and aesthetically pleasing, it can blend with modern designs, reducing the sense of oppression on the street space.

    Reinforcement and replacement of old bridges: Leveraging their advantage of light self-weight, old concrete beams can be replaced without disrupting traffic or significantly reinforcing the substructure.