Behaviour of equipment mounted over a torsionally coupled structure with sliding support

Behaviour of a light equipment system mounted over a torsionally coupled and sliding primary system, is studied under bidirectional ground excitation. A fictitious spring model is considered in the analysis to deal with the discontinuity nature of the sliding structural system. The rigid friction-force deformation characteristics of a sliding base are modelled as elasto-plastic with high elastic stiffness. The sliding structure behaves as an elastic system during the sliding phase and as a plastic system during the non-sliding phase. Responses of the equipment system are calculated by considering interaction and non-interaction between the primary system and the equipment system as well as non-interaction between the lateral and torsional resistances at the sliding support. The results presented here are of interest in the area of vibration isolation of important structural systems. (C) 1999 Elsevier Science Ltd. All rights reserved.