Parametric Analysis of Earthquake Isolation for Long-Span Spatial Structure Roof Systems

ZHOU Yuhang; HUANG Xiangyun; ZHANG Ying; HOU Jifan

doi:10.13512/j.hndz.2026.01.11

Abstract：Aiming at the problem that the large-span space structure with roof isolation design may lead to an in-creased response of the lower frame structure to increase,this paper utilizes the simplified three-mass model and its equations of motion to derive the transfer function of the structure via Laplace transform,and compares the re-sponses of the conventional seismic-resistant structure,the roof-isolated structure,and the Tuned Mass Damper(TMD)structure under different excitation frequencies.Furthermore,by adjusting the mass of the upper roof struc-ture,the seismic response of the ground vibration roof isolation structure under different mass ratios was compared and analyzed.When the mass of the roof structure is relatively small,with mass ratio μm3 of 3%,5%,and 6%,optimal damping cannot be achieved if the natural frequency of the roof structure is deviates from the first-order nat-ural frequency of the main structure.Moreover,the insufficient mass cannot effectively lengthen the structural pe-riod,resulting in increased seismic demands on the lower frame structure.However,for these small mass ratio(μm3 for 3%,5%,6%),adjusting the stiffness of the roof structure so that its frequency approaches the first-order natural frequency of the main structure can reduce the seismic demands on the lower frame stucture,achieving a tuned damping effect analogous to that of a TMD.Nevertheless,this approach simultaneously increases the seis-mic demands on the roof structure itself,which is unfavorable for the grid structure.In contrast,by significantly increasing the mass of the roof structure to a mass ratio μm3 of 30%,the response of the lower frame structure can be reduced,primarily realized through period elongation.