Steel Box Girder Bridge with big loading capacity and high stiffness.

The steel box-girder bridge is generally composed of:

• Top plate (bridge panel)
• Beam web
• Bottom plate
• Longitudinal stiffener and transverse stiffener
• Diaphragm plate (cross beam)

The thickness of the top plate, beam web and bottom plate is generally 12~30mm, and the thickness of the secondary plate is 10~20mm.

Usually adopted manufacturing fragments in factory (section length is generally 10-30m, depending on transportation and hoisting conditions) and site welding.

To ensure the quality of welds, welding in factory should be adopted as far as possible, and should strictly check the weld quality.

Scope of application: when the bridge width is small (3 lanes) or width to span ratio <1/10.

For 4~6 lanes, double width single box girder bridge can be adopted.

Scope of application: when the bridge width is large or the single box size, production, transportation, installation is difficult or the effective width of a single box is small and uneconomical.

Scope of application: when the span is small and the bridge width is large.

Effect: When the main beam spacing is large, the span of the reinforced concrete bridge panel should be reduced; improves the stiffness of steel bridge panels.

Effect: For two or more boxes, made the main beam stressed evenly; supports longitudinal beams or bridge panels.

Two supports should be installed at the end of a single-box steel beam bridge to ensure structural stability and resistance to torque.

• Under the action of bending moment, the compression flange is partially unstable and occurs bending failure
• The box girder is distorted under the action of torque
• Under the action of concentrated force, the nearby beam web was crumpled failure

• Provide adequate transverse partitions to avoid distortion and lateral bending
• Provide enough stiffening ribs to prevent the local instability of the compression flange
• Arrange stiffening ribs to prevent local compressive stress or out-of-plane bending
• Set up transverse ribs and longitudinal ribs to prevent the buckling of web and local creasing

• Highway and road bridges
• Railway bridges
• Pedestrian and cycling bridges
• Urban infrastructure
• Overpasses and flyovers
• Emergency or temporary bridges

• The flange width is large, with great bending resistance and large span
• Large torsional stiffness, uniform lateral load distribution, suitable for curved bridge
• The transverse flexural stiffness is large, the horizontal resistance is strong
• The single box girder has good overall stability and fast construction
• Small beam height, suitable for overpasses and bridges with limited building height
• Beautiful appearance, transverse and stiffening structure are in the box
• The box is hollow structure, easy to arrange ancillary facilities, repair and maintenance

• Light weight, save steel
• Quick installation and easy maintenance
• Suitable for forming continuous beams
• Novelty structure, the shape is simple and beautiful