When did they start putting rocker bearings on bridges?
In the 1920s, rocker bearings were introduced into highway bridges. After World War II, rocker bearings were also used for bridges with longer span lengths. To accommodate longitudinal thermal expansion and contraction of those spans, taller rocker bearings with adequately sized rocker plates were required.
How tall should the bearings be on a bridge?
The minimum heights of bearings were described by the National Cooperative Highway Research Program ( NCHRP, 1977: p. 8): ‘Bearings should be arranged with at least 152 mm (6 in.) clearance between the pier and the soffit of the beams. This clearance is a minimum to allow for cleaning or jacking when bearings must be repaired.
What are the two states of rocker bearings?
This paper concerns rocker bearings which are non-redundant components and have two states: stable and toppled over. When these bearings topple over, no alternate load paths exist, which results in a failed superstructure.
Why are the bearings on my Bridge not working?
The lack of maintenance of bearings, however, tends to be more the rule than an exception; thus, debris in bearings is often present, decreasing the ability of the bearings to accommodate thermal movement. As such, even ‘movable’ bearings transfer significant horizontal forces, frequently causing damage on the super- or substructure.
What happens to rocker bearings in a bridge?
This paper concerns rocker bearings which are non-redundant components and have two states: stable and toppled over. When these bearings topple over, no alternate load paths exist, which results in a failed superstructure. As such, rocker bearings are critical bridge components.
The minimum heights of bearings were described by the National Cooperative Highway Research Program ( NCHRP, 1977: p. 8): ‘Bearings should be arranged with at least 152 mm (6 in.) clearance between the pier and the soffit of the beams. This clearance is a minimum to allow for cleaning or jacking when bearings must be repaired.
This paper concerns rocker bearings which are non-redundant components and have two states: stable and toppled over. When these bearings topple over, no alternate load paths exist, which results in a failed superstructure.
Is the rocker a part of the wheel?
The rocker is in fact nothing but a section of a wheel, the weight being carried on the axle and the wheel rolling on its circumference. There are two objections to a rocker bearing: the great weight that must be carried on the axle and the friction on this axle.