Types of Steel Box Girder Bridges

Steel box girder bridges use hollow, rectangular sections for load-bearing. They are classified by cross-section, function, and construction method.

1. By Cross-Section

• Single-Cell Box Girder: One enclosed chamber; good torsional resistance (e.g., urban viaducts).

• Multi-Cell Box Girder: Internal diaphragms improve strength (e.g., cable-stayed bridge decks).

• Twin Box Girders: Separate boxes for wide decks or wind stability (e.g., Akashi Kaikyo Bridge).

2. By Structural Function

• Simply Supported: Single-span, easy to erect (spans 20–50 m).

• Continuous Spans: Multi-span for smoother decks (spans >200 m).

• Variable Depth Girders: Optimized for bending moments (e.g., Chongqing Caiyuanba Bridge).

3. By Construction Method

• Full-Span Launching: Prefabricated sections lifted into place (for river crossings).

• Cantilever Assembly: Segments added symmetrically from piers (e.g., Humen Bridge).

• Incremental Launching: Pushed longitudinally into position (e.g., Ganter Bridge).

• Swing Erection: Rotated into place over obstacles (e.g., railway crossings).

4. Special Types

• Flat Steel Box Girders: Low-profile for aerodynamics (e.g., Great Belt Bridge).

• Composite Box Girders: Steel box + concrete deck (e.g., Shanghai Lupu Bridge).

• Corrugated Steel Web Girders: Reduces weight (e.g., Japan’s Tamagawa Bridge).

Advantages: Lightweight, long-span capability, fast construction.
Challenges: Corrosion protection, buckling risk in thin-walled sections.

Iconic Examples:

• Millau Viaduct (France): Multi-cell box girders.

• 1915 Çanakkale Bridge (Turkey): Suspension bridge with steel box deck.