Stability of rocking structures

Previous studies on the stability of rocking structures subjected to earthquake motions have focused on the development of numerical tools to estimate dynamic response. These tools have not been successful in reproducing the response of a rocking structure to earthquake motions. The sensitivity of the numerical results to small variations in the input parameters is the main reason cited by researchers to explain unsuccessful simulations. This study examines the use of an alternative method to estimate the stability of rocking structures subjected to earthquake motions. Since its proposal, no experimental work has been done to test the method systematically. This study will attempt to fill that gap in the current literature on rocking structures. An experimental program was conducted including 312 tests of concrete blocks subjected to simulated earthquake motions. The experimental results presented here support the hypothesis proposed that a block, not fastened to the ground, may overturn during an earthquake if its aspect ratio (ratio of dimension parallel to the direction of motion to height) is less than:[special characters omitted] where [special characters omitted] Sv is the spectral velocity for a given earthquake motion. The experimental results suggest that Sv should be computed as the mean spectral velocity for linear oscillators with periods ranging from 0.5 to 3.0 sec. and a damping ratio of 2%