The steel truss bridge is a structural system between beams and arches. It is a structure in which a bent upper beam structure and a pressure-bearing lower column are integrated together. Due to the rigid connection between the beam and the column, the beam is unloaded due to the flexural rigidity of the column. The entire system is a compression-bending structure as well as a thrust structure.

The rigid truss beam bridge consists of:

• Main girder
• Bracing
• Bridge deck system
• Bridge floor

According to the different position of the bridge floor, it is divided into:

• Upper bearing steel truss bridge: The bridge floor is located in the upper part of the main truss
• Lower bearing steel truss bridge: The bridge floor is located in the lower part of the main truss

(1) Main Girder: The main load-bearing structure that bears vertical loads. Composed of upper chord, lower chord and belly rod (divided into diagonal bar and vertical bar). Nodes are divided into large nodes and small nodes. Pitch refers to the distance between nodes.

(2) Bracing:

• Classification: Longitudinal connection and horizontal connection
• Function: Connects the main truss, making the bridge span structure become a stable space structure that can withstand various lateral loads
• Longitudinal connection system: Divided into upper and lower horizontal systems, mainly withstands transverse horizontal loads
• Transverse connection: Divided into bridge frame and crosslink, increases torsional stiffness of steel girder

(3) Bridge Deck System: Composed of the longitudinal beam, beam and the connection between them. Load transmission path: load → longitudinal beam → beam → main truss.

(4) Bridge Deck: The part for vehicles and pedestrians to walk on, with forms similar to steel beam bridges and combined beam bridges.

• Beautiful building appearance
• Good seismic performance
• Large span capability
• Fast construction speed
• Wide application range
• Customizable designs
• Energy efficient
• Economical with simple structure
• Easy to standardize, manufacture and install

Steel truss bridges have diverse applications depending on span length, load requirements, site conditions, and architectural considerations:

• Emergency or Temporary Bridges
• River and Waterway Crossings
• Industrial Bridges (for transportation of goods and materials)

Triangular Truss: Simple structure, fixed design, easy to install and manufacture.

Diagonal Bar Truss: Features many bar specifications, large internal force of the vertical rod, and all large nodes.

K-shaped Truss: The shear force is borne by two diagonal rods, which are small and short in section. Features many specifications, nodes, and connections. Suitable for small/medium spans (complex structure) or large spans (lightweight for mounting/dismounting).

Double-vented Bar Truss: Shear force borne by two diagonal rods (small/short sections). Ideal for large spans with short compression rods (good buckling stability). Fewer connecting pins make joint arrangement easier.