| As a relatively mature seismic control means,isolation technology can effectively decrease upward transmission of seismic force and reduce seismic response of superstructure by setting the stiffness of isolation layer less strong.However,if the horizontal stiffness of the isolation layer is designed too soft,the structure will be very sensitive to external excitation,which is undesirable in design.In this paper,the concept of negative stiffness is introduced to ensure structure have enough initial stiffness to resist wind load or environmental excitation.When the earthquake happens,the isolation layer with negative stiffness device(NSD)can achieve the seismic response similar the lower stiffness of isolation layer.This paper is based on characteristic that NSD reduces lateral stiffness of structure.The main contents can be summarized as follows:(1)Based on deducing constitutive of NSD,account for the working principle of NSD.Then,studying the influence of component parameters to the constitutive of NSD.(2)Based on a numerical model with only three parameters,the constitutive equation of the negative stiffness device is simplified.And the relation between the constitutive of NSD and the structural characteristics is established.Based on this,parametric design for NSD.(3)Based on an adaptive negative stiffness structure system,the dimensionless parameters of adaptive negative stiffness system are derived through rigorous dimensionless analysis.In the elastic and plastic stage of structures,studying the effect of yield displacement,damping ratio of damper and three parameters of NSD on response of structures.(4)Taking three-layer frame structure as research object,by comparing and analyzing unisolated structures,isolation structures with and without NSD,and study the initial stiffness of isolation layer with NSD.By properly increasing the stiffness of isolation layer,the sensitivity of structure to external excitation can be reduced,and seismic response of isolated structures with NSD can be effectively reduced and achieve the isolation effect similar the lower stiffness of isolation layer. |
