The Research Of Floor Response Spectrum Considered Vibration Characteristics Of Cabinet Equipment

The isolated structure is usually used in some buildings with high functional demand,such as hospitals,substations,laboratories,telecommunication control centers,etc.These buildings are usually placed a lot of expensive and sophisticated equipment,but the general structure design does not take into account the reaction of these equipment,simply think of fixed connection with equipment and structures completely,and put the weight of equipment into equivalent static load on structures,ignoring the dynamic response of the equipment.In fact,the reaction characteristics of equipment are closely related to equipment dynamic characteristics and the connection mode of equipment and structures.In addition,even if the isolation technology is used,the structure design method also can’t completely protect the safety of equipment and maintain buildings’ function.So the dynamic characteristics of equipment should be considered roundly to analyze the vibration characteristics of equipment with different support forms in earthquake,and the floor response spectrum of isolated structures to provide a reasonable simplified design method for unstructured components.Therefore,this paper takes the cabinet equipment as the research object,analyzes the vibration characteristics of this equipment,and gives the floor response spectrum for isolated structures.The main research contents and conclusions are as follows:(1)The connection forms of equipment and isolated structures can be divided into fixed and floating forms,and vibration form of floating equipment is divided into sliding and overturning.The motion equations of the three types of equipment,fixed,floating-sliding and floating-overturning are established respectively,and the relationship between the maximum response of three types of equipment and the geometric parameters of equipment was established.(2)Use OpenSEES to establish isolated structures and fixed equipment and elastic time history analysis to calculate the floor response spectrum of fixed equipment,analyze the influence of ground characteristics,equipment’s location,damping effect and the dynamic characteristics of the upper structure on floor response spectrum.The results show that high mode of isolated structure has the greatest influence on the floor response spectrum,principal mode and high mode of non-isolated structure has the greatest influence on the floor response spectrum.The equipment with large self-vibration period may be more affected by earthquake in isolated structure.The equipment placed in the middle stories of isolated structures and in the first story of non-isolated structures of the seismic structure are affected by a smaller earthquake.Improving the shock absorption effect and making structures "flexible" also take advantage to the equipment.(3)Based on the relationship between peak acceleration and sliding displacement of floating-sliding equipment,the constitutive model of link between structures and equipment can be built in OpenSEES.Then calculate response by elastic-plastic time history,set sliding displacement as ductility,calculate the floor response spectrum of floating-sliding equipment,and analyze influence on floor response spectrum of equivalent linearization method,ground characteristics,damping effect,ground motion strength.The results show that the peak value of elastoplastic floor response spectrum of floating-sliding equipment increases with the increase of friction coefficient.Due to the effect of equivalent period and equivalent damping ratio,the influence of the ground characteristics and the effect of shock absorption on the elastoplastic spectrum is different from that of the elastic spectrum.(4)Based on the relationship among peak acceleration,rotation angle and aspect ratio of floating-overturning equipment,the constitutive model of link between structures and equipment can be built in OpenSEES.Then calculate response by elastic-plastic time history,set rotation angle as ductility and elastic-plastic stiffness ratio as second stiffness coefficient,calculate the floor response spectrum of floating-overturning equipment,and analyze influence on floor response spectrum of equivalent linearization method,ground characteristics,damping effect,ground motion strength.The results show that the peak value of elastoplastic floor response spectrum of floating-overturning equipment increases with the increase of aspect ratio.The influence of these factors to this spectrum is basically the same as that of the floating-sliding floor response spectrum,indicating that the second stiffness coefficient has a very limited influence on the elastoplastic floor spectrum.(5)From comprehensive analysis of the three floor response spectrum above,floating-sliding equipment floor response spectrum of isolated structures of ? =0.5 has the best envelope,and value of the elastic floor response spectrum of non-isolated structures need to be slightly larger after the self-vibration structure period to increase the envelop of the floor response spectrum.