What are the types of bridge expansion joints?

Bridge expansion joints are a crucial component of bridge structure, mainly used to cope with the expansion and contraction deformation of bridges caused by temperature changes, vehicle loads, concrete shrinkage creep and other factors, and ensure the safety and driving comfort of the bridge structure.

According to different structures and materials, bridge expansion joints are mainly divided into the following types:

Modular expansion joints

Structure: It is composed of special-shaped steel beams, sealing rubber belts, anchoring systems, etc., and adapts to different telescopic amounts through the combination of multiple sets of modulus units.

Features: Strong bearing capacity, good deformation adaptability, suitable for large-span bridges or heavy-duty traffic sections.

Application: Highways, urban expressways and other large bridges.

Comb plate expansion joints

Structure: It is made of combed toothed steel plates that are staggered and interceded, and adapts to deformation through the sliding between steel plates.

Features: Simple structure, smooth driving, but weak dustproof and waterproof performance.

Application: Medium and small span bridges or pedestrian bridges.

Rubber expansion joints

Structure: Made of rubber material (such as neoprene), adapted to expansion and contraction through elastic deformation.

Features: Good sealing, low noise, but poor durability, need to be replaced regularly.

Applications: Lightweight bridges or noise-sensitive areas.

Seamless expansion joints（TST expansion joints）

Structure: Fill the bridge seams with elastomeric materials such as TST thermoplastic elastomers to create a continuous surface.

Features: No mechanical parts, comfortable driving, but limited ability to adapt to deformation.

Application: Small and medium-span bridges or old bridge renovation.

How it works:

Bridge expansion joints perform the following functions through elastic materials or mechanical structures:

Longitudinal telescopicity: allows the beam body to expand and contract along the axis of the bridge when the temperature changes.

Lateral displacement: adapt to lateral swing caused by earthquakes, wind loads, etc.

Vertical Angle: Compensates for the corner deformation caused by uneven settlement or load of the beam body.

Sealed and waterproof: Prevent rainwater and debris from penetrating inside the structure through rubber bands or elastic materials. 

Modular expansion joints are composed of side beams, middle beams, beams, displacement control boxes, rubber sealing belts, anchoring systems (such as anchor bars, pressure-bearing bearings, and compression bearings). Part Functions:

• Side and middle beams: Steel profiles are used to directly bear the load on the wheels and transmit the force to the beams.

• Beam: Supports the middle beam to form a stable load-bearing structure.

• Displacement control box: ensure that the gap between each beam body is uniform during the expansion and contraction process to avoid stuttering.

• Rubber sealing belt: waterproof and dustproof, reducing noise and vibration while protecting the internal structure.

• Anchoring System: Securely attaches expansion joints to the bridge body, preventing loosening.

Features:

• It is suitable for large span bridges, with a maximum displacement of up to 2000mm (such as multi-set modular seams).

• Reliable transmission, strong waterproof performance, smooth driving.

• Representative models:GQF-MZL type(connecting rod chain type),GQF-C type(Vertical bearing type) and so on.