Rocking and overturning response of rigid bodies to earthquake motions: A report of an analytical and experimental study on the rocking and overturning response of rigid blocks to simultaneous horizontal and vertical accelerations

A fundamental study of the rocking and overturning response of massive concrete blocks (with relatively high aspect ratio) to simultaneous horizontal and vertical earthquake ground motions is presented. This problem occurs when large concrete blocks are used as radiation shields in particle accelerators or similar nuclear installations. The results of this study also offer insight into the response of the rigid bodies (such as are approximated by some electrical machinery and mechanical equipment) which are not anchored to the ground. The mathematical model used was based on the assumption of a constant coefficient of restitution. A computer program was written to predict the rocking and overturning behavior of rigid rectangular blocks under simultaneously applied horizontal and vertical ground accelerations. Using the computer program, the response of rigid blocks of various aspect ratios and sizes was studied under the accelerograms of various strong motion earthquakes.