Bridge bearings are devices for transferring loads and movements
from the deck to the substructure and foundations.
In highway bridge bearings movements are accommodated by the basic mechanisms of internal deformation (elastomeric), sliding (PTFE), or rolling. A large variety of bearings have evolved using various combinations of these mechanisms.
Plane Sliding Bearing
Multiple Roller Bearing
The functions of each bearing type are :
The designer has to assess the maximum and minimum loads that the deck will exert on the bearing together with the anticipated movements (translation and rotation). Bearing manufacturers will supply a suitable bearing to meet the designers requirements.
Bearings are arranged to allow the deck to expand and contract, but retain the deck in its correct position on the substructure. A 'Fixed' Bearing does not allow translational movement. 'Sliding Guided' Bearings are provided to restrain the deck in all translational directions except in a radial direction from the fixed bearing. This allows the deck to expand and contract freely. ' Sliding' Bearings are provided for vertical support to the deck only.