The Research On Floor Response Spectrum Of Isolated Structure-Equipment Composite System

Floor response spectrum is an important method for seismic analysis of equipment.At present,floor response spectrum is mainly aimed at non-isolation structure.If the floor response spectrum of non-isolation structure is directly analyzed for equipment in isolation structure,there may be a big error.The reason is that the dynamic characteristics of isolation structure are different from that of non-isolation structure,which makes the parameters of isolation layer,equipment parameters and even site characteristics different.The influence of these factors on floor response spectrum is also different from that of non-isolation structures.In addition,the existing research mostly regards isolation structure as linear elasticity,without considering the interaction between isolation structure and equipment,while isolation structure is a non-linear structure,and is mostly used in substations,hospitals,laboratory buildings and other buildings with higher requirements for use functions.These buildings usually place a large number of equipment,resulting in the coupling between equipment and structure can not be ignored.Therefore,considering the coupling of equipment and isolation structure,this paper establishes the floor response spectrum of isolation Structure-Equipment combination system,and gives the design method of equipment seismic response spectrum based on isolation structure floor design.The main research contents and conclusions are as follows:(1)The SIMULINK dynamic analysis model of isolation Structure-Equipment combination system is established.Two actual isolation structures are selected and the mean spectrum of floor acceleration amplification factor is obtained as floor response spectrum.The influence of equipment dynamic characteristics,isolation structure dynamic characteristics,building site and equipment location on floor response spectrum is discussed.The results show that the coupling effect of isolation Structure-Equipment is only related to that of isolation structure.When the mass ratio of the equipment to the floor is more than 1% or the damping ratio of the equipment is larger,the coupling effect between the equipment and the structure should be considered,while the parameters of the isolation layer,the site characteristics and the location of the equipment have no effect on the coupling effect between the isolation structure and the equipment.With the decrease of the pre-yielding stiffness and the yield force of the isolation layer,the spectral value of the floor spectrum decreases and the peak value of the spectrum corresponds.The equipment period increases,especially the equipment period corresponding to the second spectrum peak: the site type will affect the spectrum value of the floor spectrum,of which the category ? site is the smallest,while the category ? site is the largest;the influence of different locations of the equipment on the floor spectrum of the isolation structure is negligible.(2)Based on the spectral characteristics of acceleration response spectrum of isolated structure floor,the design response spectrum of isolated structure floor with bispectrum peaks is established.The least squares method is used to calibrate the response spectrum of floor design.Through orthogonal test statistics,the significant influencing factors of the control parameters in the response spectrum of floor design are analyzed,and then the calculation formulas of the parameters are fitted.The results are compared with the actual response spectrum of floor design.The results show that the response spectrum of the isolated structure designed in this paper is real,regardless of the spectrum shape or the spectrum value.The close inter-spectrum indicates that the response spectrum of the floor design of the isolation structure established in this paper is more reasonable.(3)Based on the floor design response spectrum of the isolated structure,the aseismic design method of the equipment in the isolated structure is given.The results show that the average error between the proposed method and the results of time-history analysis is 15%.The simplified method can be used for seismic design of ancillary equipment.