The Earthquake Engineering Online Archive

Mechanics of low shape factor elastomeric seismic isolation bearings

Aiken, Ian D.; Kelly, James M.; Tajirian, Frederick F.

UCB/EERC-89/13, Earthquake Engineering Research Center, University of California, Berkeley, 1989-11, 179 pages (515/A354/1989)

The results are presented of an experimental and analytical study of low shape factor (LSF) elastomeric seismic isolation bearings. The test bearings were designed to provide horizontal and vertical isolation. This dual requirement led to a bearing design with a shape factor smaller than usual for bearings designed to provide horizontal isolation only. An extensive series of tests was undertaken to investigate the performance characteristics of different types of bearings. One particular objective was to evaluate the merit of the standard cyclic shear test (with constant axial load) as a representative test for more generalized loading conditions. On the basis of the test results, a number of comparisons were made of the different bearings, with particular emphasis on evaluating the consequences of a low shape factor. Design equations for elastomeric bearings were reviewed for their particular suitability to LSF bearings. A previously developed analytical model for the prediction of bearing behavior was reviewed and extended for application to LSF bearings. The suitability of the model was evaluated in light of the experimental results.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-89-13.pdf (7 MB)