Gas insulated metal-enclosed switchgear（GIS） is usually arranged on the second floor of indoor substation.The floor electrical equipment is subjected to a strong dynamic response due to the ground motion amplification effect of the integrative building.Based on a 220 kV indoor substation structure

a finite element model of all floor electrical equipment is established.Then dynamic characteristics analysis and seismic time history response analysis are carried out for the overall model of integrative building-floor GIS electrical equipment and the model of integrative building without considering the floor equipment.The results show that:① The first 3 order frequency and the structural mode of the main structure model and the main-attached structure model are similar;②the peak acceleration amplification factor of second floor exceeds 2.0;the peak acceleration amplification factor of third floor exceeds3.0;③because of the vertical vibration of the GIS cantilever bushing

the stress response of the root of hanger and the end of the GIS cantilever bushing is large.It is suggested that the seismic analysis should consider the amplification effect of the integrative building structure on the ground motion

and appropriately increase the value of the dynamic response amplification factor of the floor.