Rocking Response and Overturning of Equipment Under Horizontal Pulse-Type Motions

摘要

In this report the transient rocking response of electrical equipment subjected211u001eto trigonometric pulses and near-source ground motions is investigated in detail. 211u001eFirst the rocking response of a rigid block subjected to a half-sine pulse motion 211u001eis reviewed. It is shown that the solution to a half-sine pulse motion is 211u001ereviewed. It is shown that the solution presented by Housner (1963) for the 211u001eminimum acceleration amplitude of a half-sine pulse that is needed to overturn a 211u001erigid block is incorrect. In reality, under a half-sine pulse, a block overturns 211u001eduring its free vibration regime and not at the instant that the pulse expires, 211u001eas was assumed by Housner. Within the limits of the linear approximation, the 211u001ecorrect conditions for a block to overturn are established and the correct 211u001eexpression that yields the minimum acceleration required to overturn a block is 211u001ederived. Subsequently, physically realizable cycloidal pulses are introduced and 211u001etheir resemblance to recorded near-source ground motions is illustrated. The 211u001estudy uncovers the coherent component of some near-source acceleration records, 211u001eand the overturning potential of these motions is examined.