Abstract: The dynamic analysis model of isolated structure-equipment coupled system was established in SIMULINK environment. The dynamic responses of two actual isolated structure-equipment coupled systems were calculated by time history analysis with multiple ground motions, and the mean spectrum of the floor acceleration amplification factor was obtained as the floor response spectrum, and compared with the floor response spectrum of the isolated structure without considering the coupled effect. The effects of equipment dynamic characteristics, isolated structure dynamic characteristics, building site and location of equipment on floor response spectrum of isolated structure-equipment coupled system were discussed. The results show that with the increase of equipment mass and damping, the coupled effect between isolation structure and equipment becomes more obvious. Especially when the mass ratio of equipment to floor is more than 1%, the coupled effect between equipment and structure should be considered. The dynamic characteristics of isolated structure, equipment dynamic characteristics and site conditions all affect the spectrum value and spectrum shape of floor response spectrum, but the effect of different locations of the equipment on the floor spectrum is tiny and can be neglected.

Key words: isolated structure, equipment, coupling, floor response spectrum, SIMULINK