| Title | Cyclic Testing of Full-Size Unison Seismic Isolation Bearings |
| Authors | Kelly, James M.; Clark, Peter W.; Whittaker, Andrew |
| Publication | Report No. EERCL-STI/97-02, Earthquake Engineering Research Center - University of California, Berkeley, September 1997. |
| Objectives | To investigate the properties of Unison high-damping rubber bearings under a range of loading conditions including axial stress, loading direction, and temperature. |
| Abstract | This report summarizes a series of tests on full-scale, high-damping elastomeric bearings supplied by Unison Corporation, South Korea. All tests were performed in Building 420 of the Earthquake Engineering Research Center at the University of California's Richmond Field Station. A total of six full-size seismic isolation bearings were tested in the Center's Large Bearing Test Machine (LBTM). The test program was designed to investigate the properties of the bearings under a range of loading conditions including axial stress, loading direction, and temperature. In the cyclic shearing tests, the differences between the three pairs of bearings tested were less than 10 percent for both shear modulus and equivalent viscous damping. Similar results were obtained for the three pairs of bearings following testing at a rotation angle of 90 degrees. For the roll out tests, the horizontal displacements at the limit state increased with increasing axial compressive stresses. In the temperature tests, it was found that the shear modulus of the tested bearings, the rubber for which was compounded to minimize temperature effects, increased by less than 40 percent when tested at -20 C (-16 F). |
