Roaby, leading the technical revolution of bridge expansion joint worldwide! Its RB unit finger expansion joint with multi-directional displacement capability (RB finger joint) is a breakthrough product which reaches a high level of expansion joint technology, solving the technical difficulties of expansion joint in large-scale and long-span bridges.


I.History of Bridge Expansion Joint

Along with the economic development, the public has higher expectation on driving comfort, safety, and reliability. As one of the major components of the bridge structure related to driving safety and comport, the bridge expansion joint has gained growing attention. Its major role is to accommodate the bridge longitudinal, transverse and vertical movements and rotations caused by thermal, wind, traffic and seismic loads without any compromises to structural performance and rider's comfort.


Cantilever finger joints with popularity in Europe and America from 1970s to 1980s have the advantages of relatively low initial cost, compact design with few components and low maintenance costs, but they have very limited movement capacity, which limit their applications in long bridge structures.


After 1980s, with the trend of bridge construction in China to build longer and larger bridges, modular joints have been imported from western countries. These products are still being widely used due to the advantages of large movement capacity and easy installation. The major components of this type of expansion joint are: lamella beam, supporting beam, bearing and rubber seal.


Although this type of joint has been widely used for many projects, there are growing concerns about its long-tem performance. The major defects reported are profile steel rupture, bearing fall off and rubber seal break, which may cause sufficient damage to led to serious traffic accidents. In addition, its small transverse, vertical movement and rotation capacity and large block-out space requirement needed for installation make it not suitable for large scale bridges such as suspension bridge, cable stayed bridge and long continuous span type of bridge.