The development of hysteretic dampers for the protection of structures against earthquake attack, carried out at the Physics and Engineering Laboratory over the past six years, is described.
Details of both steel and lead devices and their application to
bridges and base isolated buildings are given. Steel devices are designed to absorb energy by plastic deformation in torsion or
bending, while lead devices rely on plastic extrusion or shear.
The characteristics of PTFE sliding bearings are also described and the possibility of using this type of bearing to permit sliding on base isolated systems, and to allow dissipation of energy in joints in conventional structures, referred to. The most promising development is in the lead rubber bearing in which the properties of load-bearing and damping are combined in one unit.