The steel box-girder bridge is a high-strength structural solution composed of top plate (bridge panel), beam web, bottom plate, longitudinal stiffener, transverse stiffener, and diaphragm plate (cross beam).

This hollow, rectangular or trapezoidal-shaped steel box structure provides exceptional strength, stiffness, and durability, making it ideal for long-span applications and heavy load-bearing requirements.

• Top plate, beam web and bottom plate thickness: 12-30mm
• Secondary plate thickness: 10-20mm
• Manufactured in factory fragments (10-30m sections) with site welding
• Orthotropic steel bridge panels with open/closed longitudinal rib sections

Ideal for bridges with width ≤3 lanes or width-to-span ratio <1/10. Features effective flange width with main beam web interval ≤Le/5 and cantilever length ≤Le/10.

Used when bridge width makes single box impractical due to size, transportation, or installation constraints.

Optimal for small-span, wide bridges with uniformly spaced main beams for even load distribution.

Proper support configuration is critical for stability and load distribution:

• Single-box bridges require two end supports for torque resistance
• Multi-box bridges use one support per steel box
• Temporary fulcrum supports with jacks strengthen during construction

• Lightweight construction with steel savings
• High flexural and torsional stiffness
• Rapid installation and easy maintenance
• Excellent for continuous beam formation
• Aesthetic, streamlined appearance
• Large span capabilities exceeding other bridge types
• Superior wind resistance and stability
• Hollow structure facilitates maintenance access