Pamela J. Romano
MCEER REU 2001
July 30, 2001
As a participant in the REU program sponsored by MCEER at the University at Buffalo, I worked with a couple graduate students testing low and high-damping and also lead core rubber bearing isolators. All of the bearings are cylindrical with a height of 5.02” and a diameter of 7.25”. Encased in the rubber are steel shims, which provide vertical strength. The elastomer of the low damping and the lead core is identical, and the high damping bearing has a stiffer elastomer. All bearings have a one-inch diameter hole bored through the middle, with the lead core bearings filled with lead.
Through testing and analysis of the rubber bearing isolators, characterization of these bearings can be achieved. The bearings tested are the same as those tested two years prior by a graduate student. Using the results from these tests and also the previous tests, a better understanding of the behavior (recovery rate, stiffness and damping) of the bearings will be attained.
Using the Small Bearing Testing Machine and the following schedule (fig. 1), the low damping and one of the lead core bearings have been tested. The testing of the high damping and second lead core bearings is scheduled for this week. The tests ran subsequent to the previous, except the recovery, which was run the next day.
These test are similar to the ones run previously on the same bearings. Since the only difference in the testing is the bearings being previously scragged and allowed to recover for two years, similar results should be seen.
These bearings are needed in buildings where considerable amounts of seismic activity occur. By isolating the structure from the ground movement, less force and acceleration is transmitted. These tests will allow for a greater understanding of how the bearings will withstand shear forces and also vertical loads over a greater period of time.