ASSESSMENT OF SLIDING MATERIALS FOR PENDULUM ISOLATION BEARINGS

An experimental procedure is proposed for assessing the frictional behavior of selflubricating materials used in the primary sliding surfaces of pendulum isolation bearings under both service movements and seismic loading. The sliding properties are characterized in small scale tests on a custom jig, and the dependence on pressure, ambient temperature and velocity is investigated. The methodology has been used for the assessment of two novel thermoplastic materials with different sliding characteristics and friction coefficients. To validate the proposed procedure, prototypes of pendulum isolators incorporating such materials have been then tested according to AASHTO widely used specifications and the dynamic properties determined from the hysteretic force – displacement loops. The prototype tests have confirmed the reliability of the results of the small scale characterization when extrapolated to real working conditions