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 bi-directional 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.