M A ELGAWADY, Q MA, J BUTTERWORTH, and J M INGHAM
Department of Civil and Environmental Engineering, The University of Auckland
The rocking response of rigid blocks with aspect ratios of 3 and 5 was investigated, with particular focus on the possible effects of interface material. The blocks were allowed to rock on reinforced concrete and rubber bases. Preliminary results showed that the interface material exerted a significant influence on the rocking response. Blocks tested on a rubber base exhibited smaller coefficient of restitution. In addition, the rocking characteristics of the blocks were calculated using simple mathematical models based on fundamental principles of mechanics. The models were generally found to overestimate the coefficient of restitution. In the case of blocks having an aspect ratio of 5, the measured coefficients of restitution were approximately 0.95 and 0.67 of the predicted values for concrete and rubber bases, respectively. In the case of blocks having an aspect ratio of 3, the measured coefficients of restitution were approximately 0.97 and 0.82 of the predicted values for concrete and rubber bases. For tests on reinforced concrete base, the vibration energy dissipated in a step pattern. For tests on rubber base, the energy of the system followed closely the potential energy of the rocking block. In addition, part of the energy of the system is stored in the rubber due to rubber hysteretic deformations. Then, when the transition happened and the block rock around the other pivot, the pad restored (inject) part of the energy again into the system.