What is the working principle of bridge bearings?

This question raises the core functional logic of bridge bearings, which can be summarized as "force transmission+adaptation to deformation". Essentially, it is a "buffer coordinator" between the upper and lower structures of the bridge.

The bridge bearings connect the bridge deck beam (upper structure) and the bridge piers (lower structure), mainly ensuring the safety and stability of the bridge through two key functions. The specific principle is as follows:

1. Core function one: Efficient transmission of loads

Undertake all the weight of the upper structure, including the weight of the bridge deck, vehicles, pedestrians, as well as temporary loads such as snow and water accumulation.

Distribute these loads evenly and then transfer them to the bridge piers, which in turn transfer them to the underground foundation to avoid excessive local pressure that may cause damage to the bridge piers or beams.

Simultaneously capable of transmitting horizontal forces, such as the impact force of vehicle braking and the pushing force of wind on the beam, ensuring that these external forces do not directly damage the bridge structure.

2. Core function 2: Adapt to structural deformation

Bridges may deform due to various factors during use, and the bearings need to "allow" these deformations through their own design while maintaining structural stability:

Adapt to expansion and contraction deformation: Temperature changes can cause thermal expansion and contraction of the beam body. Bearings (such as elastic plate rubber bearings+and sliding devices of bowl bearings *) can allow the beam body to move slightly longitudinally or transversely, avoiding the beam body from being pulled apart or crushed.

• Adapt to rotational deformation: When a vehicle passes by or the beam is subjected to force, the beam end will undergo slight bending and rotation. Bearings (such as elastic deformation of rubber or spherical contact of bowl shaped bearings) can allow for this rotation, preventing rigid collisions between the beam and the bridge pier.

• Adapt to uneven settlement: If there is a slight difference in settlement of the bridge pier due to foundation reasons, the support can also adjust itself to balance the relative position of the upper and lower structures and reduce structural stress.

Simply put, bridge bearings are like the "joints" of a bridge - they need to be able to "bear weight" while also being able to "move flexibly", so that the bridge can withstand loads without being damaged by deformation.