Modifications in both lead and rubber properties of LRBs at low temperatures considering the size effect

Abstract

This study investigates the contribution of rubber and lead core to amplification in mechanical properties of lead rubber bearings (LRBs) when subjected to cyclic motion after low temperature exposure. In the experimental program, both large- and small-size LRBs were tested in order to observe the effect of bearing size on the results. For both sizes, tests were conducted with two identical bearings in terms of geometry. One of the bearings had a lead core while the other one did not. Displacement controlled cyclic tests were performed at a frequency of 0.1 Hz and a rubber shear strain of 100% after the bearings were conditioned at 0, −10 and −20 °C for a period of 24 h. Force-displacement loops recorded during the tests were used to compute hysteretic properties of bearings with and without a lead core. Comparison of hysteretic properties provides the contribution of the lead core to modification in post-yield stiffness of both large- and small-size LRBs. Test results showed that variation in post-yield stiffness of both large- and small-size LRBs has a similar trend which is to increase with decreasing temperature. It is also found that the contribution of lead core to post-yield stiffness depends on the size of LRB. In small-size LRB, the amount of lead core contribution to post-yield stiffness decreases with decreasing temperature while it remains almost unchanged for large-size LRB.