AASHTO-LRFD Bearing Types:

AASHTO-LRFD Bearing Types tutorial is about common bearing types and bearing suitability. First of all we need to know, bearings transfer horizontal and vertical forces from superstructure to substructure. Also, designer can decide bearings to restrain or allow movements in any direction.

Firstly, common bearing types are;

Cylindirical bearing,
Spherical bearing,
Rocker bearing,
Pot bearing and,
Elastomeric bearing.
First type is cylindirical bearing; it can be damaged under high rotations due to seismic events. Because of this, it is not good to use at skew bridges.

Second type is spherical bearing; it can carry very high axial loads while allowing movements.As a result, it can have special lubricated sliding surface at interfaces.

Other type is rocker bearing; it can be used at steel arch or truss bridges. Also it can be damaged during seismic event.

Another type is pot bearing; it can carry  high axial loads while allowing movements. Also, it can have special lubricated sliding surface at interfaces.  It has a confined rubber that allows rotation.

Last type is elastomeric bearing; it can not carry high axial loads and appropriate for short girders allowing certain amount of movements.

Finally, plain elastomeric pad and steel reinforced elastomeric bearing are suitable for movement in both longitudinal and transverse axis. Curved silinding spherical and cylindrical bearing , double cylindirical bearing and pot bearing may be suitable, but requires special considerations of additional elements such as sliders or guideways. Rocker bearing is suitable for movement in longitudinal axis. But, it is not suitable in transverse axis.