Cable-stayed bridge, also known as diagonal bridge, is a kind of bridge where the main beam is directly pulled on the bridge tower with many cables. It is a structural system composed of a pressurized tower, a strained cable and a bent beam body.

The cable-stayed bridge is mainly divided into three parts: main beam, cable tower and stay cable.

• The main beam generally adopts concrete structure, steel-concrete combination structure, steel structure or steel and concrete mixed structure.
• Cable tower - it adopts concrete, steel-concrete combination or steel structure. Most of them are concrete structures.
• Stay cable - is made of high strength material (high strength steel wire or steel strand).

The load transfer path of the cable-stayed bridge ensures that the main beam is supported by the various points of the cable, acting as a continuous beam with multi-span elastic support. This design:

• Greatly reduces internal bending moment of the beam
• Minimizes main beam dimensions (beam height is generally 1/50 ~ 1/200 of the span)
• Reduces structural weight while increasing crossing capacity

1. Twin tower three span: Ideal for crossing larger rivers due to its larger main span.

2. Single tower double span: Suitable for small and medium-sized rivers and urban channels with smaller main hole spans.

3. Three-tower four-span and multi-tower multi-span: Offers flexibility but requires careful engineering to prevent excessive deformation.

4. Auxiliary pier and side lead span: Improves structural stability and facilitates construction.

The cable tower is crucial for both structural integrity and aesthetic appeal. Common configurations include:

• Single column type (simple structure)
• A-shape (high stiffness)
• Inverted Y type (reduces negative bending moment)

The height to span ratio of the tower determines the stiffness and economy of the entire bridge.

Three primary cable plane positions:

• Single cable plane (requires box section with large torsional stiffness)
• Vertical double cable plane (resists torque through cable axial force)
• Oblique double cable plane (excellent wind resistance)

Cable surface shapes include radial, harp, and sector arrangements, each with distinct advantages.

Cable-stayed bridges can be classified by:

• Tower, beam and pier combination (floating, semi-floating, consolidated systems)
• Main beam continuity (continuous system vs T-structure system)
• Tower height (conventional vs low tower partial cable-stayed bridges)

• Exceptional crossing ability with minimized beam dimensions
• Superior wind stability compared to suspension bridges
• No need for centralized anchorage structures
• Facilitates cantilever construction methods
• Reduced material consumption and structural weight