​Introduction of Bridge expansion joints:

The expansion joint of highway bridge is a specially reserved structure when building highway bridge, mainly to prevent temperature change and other factors from affecting the safety of highway bridge.

Bridge expansion joint is a structure connecting two adjacent piers, used to buffer the expansion deformation of the bridge caused by temperature change, vehicle load and other factors.

Bridge expansion joint: refers to the expansion joint between two beam ends, between beam ends and abutment, or on the hinge position of the bridge to meet the requirements of bridge deck deformation. In parallel and perpendicular to the bridge axis, firm and reliable, the vehicle should be smooth and outdated without jump and noise; and it can prevent rainwater and garbage soil from infiltration and blocking; the installation, inspection, maintenance and dirt elimination should be simple and convenient. At the expansion joint, the railing and the bridge deck pavement should be disconnected.

Expansion joint material refers to the material used in the expansion joint of the bridge, and its performance directly affects the safety and service life of the bridge.

The role of the bridge expansion joint: it is to adjust the displacement and connection between the superstructure caused by the vehicle load and the bridge building materials. Once the expansion device of the inclined bridge is damaged, it will seriously affect the speed, comfort and safety, and even cause traffic safety accidents.

Classification of Bridge expansion joints : butted type, steel support type, combined shear type (plate), modular support type and elastic device.

Butted type
Butt joint expansion joint device, according to its structural form and stress characteristics, can be divided into filling butt joint type and embedded butt joint type two kinds.

Modular support
When the expansion deformation of the bridge exceeds 50mm, steel expansion devices are often used. When the vehicle passes by, the telescopic device is often caused by the rotation or deflection of the beam end and produces a clap effect, which is loud and easy to damage the structure. Therefore, it is necessary to use a device with bolt springs to fix the sliding steel plate to reduce flapping and noise, and the structure of the expansion joint is relatively complex.

Shear type
The device is a telescopic device using various rubber belts with different section shapes as filling materials. Because rubber is elastic and easy to paste, it can meet deformation requirements and has waterproof function. It has been widely used in bridge engineering at home and abroad.

Elastomer
Elastomer expansion device is divided into zinc sheet expansion joint and TST gravel elastic expansion joint, elastomer expansion device is a simple expansion joint device, for small and medium-sized span Bridges, when the expansion amount is within 20mm-40mm can be used TST gravel elastic expansion joint device, is the special elastomer plastic material TST heating and melting, Injected into the cleaned and heated gravel, that is, the TST gravel elastic expansion joint is formed, the gravel is used to support the vehicle load, and the TST elastoplastic body can meet the requirements of the expansion amount under the condition of 25℃ ~ 60℃.

Common types of bridge expansion joints include:

• Finger joints
• Sliding plate joints
• Modular expansion joints
• Elastomeric expansion joints
• Compression seal joints

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