Testing of friction pendulum seismic isolation bearings for bridges

Friction Pendulum bearings have been extensively tested for different environmental conditions and loadings applicable to bridges. Data are presented from various test programs, spanning six years, and including several hundred shake table and compression-shear tests. Shake table tests of bridge models were used to verify dynamic performance of the seismic isolation system. Results are reported for models of bridge decks mounted on flexible piers and rigid abutment supports, and for various types of ground motions, including standard Caltrans ground motion spectra and near fault pulse motions. Comparisons between experimental results and dynamic analysis results are presented. Compression-shear test results are reported for the effects of temperature variations from minus 20°F to 90°F, 20,000 cycles of thermal movements, simulated aging, scragging, compression overloads, and tension loads. The test results show the effect of these factors on the properties of the bearing. Results for bearing ultimate strength and factors of safety are shown. The implications for the design and application of seismic isolation to bridges are discussed. Stable and predictable responses are observed over a wide range of conditions and loadings, lending support and confidence for the application of seismic isolation to reduce earthquake hazards for bridges.