Response Spectrum Research Of Sliding Base Isolation Structure

Sliding base isolation structure is a new seismic type. It can extend natural period of structure and reduce eaithquake response by use of sliding story which separate base and top structure slides in the earthquake. It change traditionally active control model that improving stiffness and strength of structure reduce earthquake response. It show obviously seismic effect, boundless prospects and is being highly cared in seismic engineering domain.In the paper, based on the analysis of dynamic characteristics of the sliding base seismicisolation system on buildings, we build a model based on single degree of freedom kulun friction type. Though dynamic analysis for sliding base isolation structure, we calculate dynamic expressions and judgement expressions for all conditions and the response spectrum of sliding base isolation structure using FORTRAN program. Compared with the response spectrum of general structure, we can know effecting aspect of the response spectrum of sliding base isolation structure: characteristics of structure itself (friction coefficient between base and structure, damping ratio of the building and mass ratio on mass of sliding foundation and top structure) and three fundamental aspect of earthquake (earthquake intensity, characteristics of frequency spectrum and especial lasting time).we calculate the seismic response using the theory based on the response spectrum of sliding base isolation structure. Compared with general structure, sliding base isolation structure shows obvious reduction and control of seismic response. Main researches and conclusions are under:Friction coefficient is smaller, absolute acceleration and relative displacement is smaller. But friction coefficient reaches limitless maximum value, sliding base isolation structure change into base fixed structure, absolute acceleration obviously change larger.But relative displacement is not smaller than the fixed base structure. We can take the conclusion that friction coefficient exit an optimum value which make absolute acceleration and relative displacement smaller. Damping ratio of the building is greater, absolute acceleration and relative displacement of top structure is smaller. This conclusion is keep pace with that according to the fixed base structure. But the effect on absolute acceleration and relative displacement from damping ratio is reduced by period increasing. Mass ratio is greater, absolute acceleration value is greater and relative displacement value is smaller. Absolute acceleration and relative displacement are controlling object. Choosing suitable Mass ratio can make Absolute acceleration and relative displacement controlled in a credit range which is vital for seismic designment of structure. Friction coefficient, damping ratio, mass ratio all influence relative velocity of top structure in a range. But for overall natural period of structure. We can not take obvious conclusions. Earthquake intensity, characteristics of frequency spectrum and especial lasting time all influence response spectrum in a range. The influence mainly inflect on the maximum value of response spectrum. Contrast with the fixed base structure, choosing optional friction coefficient, damping ratio, mass ratio, sliding base isolation structure can effectively reduce absolute acceleration of top structure, especially T<3s.But displacement of sliding base isolation structure for large period is larger than that of the fixed base structure. By natural period increasing, absolute acceleration of sliding base isolation structure keep pace with that of fixed base structure. Even displacement of top structure exceed that of the fixed base structure. Reduction and control of seismic response for sliding base isolation structure is lost.