The life of a bridge depends greatly on the installation of vital elements, specifically bridge bearings and expansion joints. These components help in proper maintenance and channel efficient functionality of the bridges.

As the bridges are exposed to environmental factors and self-imposed phenomena, they tend to suffer from structural movements in different ways. These movements results from many primary sources such as –

·          Thermal alterations

·          Prestressing causing creep effects

·          Concrete shrinkage      

·          Elastic post-tensioning shortening

The overall behavior of the bridge structure can hamper the performance and the installation of both bridge bearings and expansion joints help in controlling the structural behavior.

Keep reading more to find out the role of these components and their significance of installation in bridges.

Expansion Joints

The movements that are mentioned above must be limited or controlled for the proper functionality of bridge structure. Except for the elastic post-tensioning shortening that typically happens prior to the installation of expansion joints, the movements are calculated to determine the design and appropriate selection of expansion joints.

Other movements that induce different phenomena comprises seismic events, live loading (horizontal and vertical braking), foundation settlement and wind. These phenomena are not considered for calculation when deciding for expansion joints.

The seismic movement may cause some damage to the expansion joints, however, that is a tolerable impact which can be subsequently repaired. On the contrary, where the bridges have seismic bearing installations, the expansion joints must be able to accommodate the seismic movements for enabling proper functioning of seismic bearings.

Also, high-quality expansion joints are able to accommodate the long-term and cyclic structure movements in such a way so as to minimize the secondary stress imposition in the bridge structure. All in all, the primary purpose of expansion joints installation is to enable continuous traffic between bridge structures and the structures that are interconnecting.

Bridge Bearings

Bridge Bearings are another vital element that is installed for improving the performance of bridges. With the application of this device, it gets easier to facilitate vehicular transfer and other imposed environmental loads from the superstructure to the substructure and eventually to the ground.

In order to carry out this function, the bridge bearings must be able to accommodate the anticipated movements (essentially thermal expansions and contractions) while simultaneously restraining the undesired movements (e.g. seismic displacements). Since the movements are essentially enabled by the adjacent expansion joints, the movement restriction imposed is carried out by the bearings.

Both the bridge bearings and expansion joints play a side-by-side performance and therefore it is essential that the both the devices are designed interdependently and in consideration with the structural behavior of the overall bridge structure.

Therefore, for longer bridge life and efficient performance, the installation of high-quality bearings and expansion joints must be considered. To get the maximum benefit, it is recommended to select tailor-made bearings and expansion joints so that they fit to the different design requirements of the structure.

Make sure that all the necessary calculations are done beforehand when considering choosing bridge bearings and expansion joints.