Important Definitions in Bridge Engineering

18. Bearings : The part of the bridge structure which bears directly all the forces from the structure above and transmits the same to the supporting structure.
19. Sliding Bearings : A type of bearing where sliding movement is permitted.
20. Rocker Bearing : No sliding movement is permitted but which allows rotational movement.
21. Sliding cum rocker Bearing: A type of bearing which in addition to the sliding movement either  the top or bottom plate is provided with suitable curvature to permit rotation.
22. Roller cum Rocker Bearing : A type of bearing, which permits longitudinal movement by rolling and simultaneously allows rotational movement.
23. Elastomeric Bearing : A bearing consisting of one or more internal layers of elastomer boarded to internal steel laminates by the process of vulcanisation. The bearing cateress for translation and/or rotation of the superstructure by elastic deformation.
24. Laminated Bearing : A bearing composed of alternate layer of elastomer and laminates integrally bonded during vulcanisation.
25. Fixed POT Bearing : A type of POT bearing which along with vertical load bears and transmits horizontal force in any director and allows rotation about any axis in horizontal plane without permitting any movement in horizontal plane.
26. True sliding type POT-cum-PTFE Bearing : A type of POT bearing which bears and transmit vertical load and  allows movement in any direction in the horizontal plane and accommodates rotation about any axis in horizontal plane.
27. Guided Sliding type POT cum PTFE Bearings : A type of POT bearing which along with vertical load bears and transmits horizontal force in one direction only and allows movement perpendicular to that direction and allows rotation about any axis in horizontal plane.
28. Free PTFE Sliding Assembly : A type of PTFE sliding assembly, which along with vertical load bears and transmits horizontal force in one direction and allows movement perpendicular to that direction.
29. Guided PTFE Sliding Assembly : A type of PTFE sliding assembly, which along with vertical load bears and transmits horizontal force in one direction and allows movement perpendicular to that direction.
30. Pin Bearing : A bearing consisting of a metal pin provided within a metal cylinder to bear and transmit horizontal free along any direction in the horizontal plane and accommodating rotational movement about any axis. Pin bearing cannot bear or transmit any vertical load.
31. Metallic Guide Bearing : A bearing consisting of a sliding assembly with restraint along a desired direction to bear and transmit horizontal force and capable of allowing movement in a direction and to the direction of horizontal force. Metallic Guide Bearings and capable of allowing rotation only about an axis perpendicular to the plane of sliding. Metallic Bearing cannot bear or transmit any vertical load.
32. Abutment : The end supports of deck of bridge, which also retains earth, fill of approaches behind fully or partly.
33. Box type Abutment and Return Wall : When the return walls on two sides are integrated with abutment and a back wall parallel to abutment is provided end of the returns with or without additional internal wall along or across length, this structure is called box type abutment and return wall or end block.
34. Spill through Abutment: An abutment where soil is allowed to spill through gaps along the length of abutment such as column structure where columns are placed below deck beams and gap in between is free to spill earth.