Performance-based Seismic Design Of Structures With Added Viscous Dampers

The passive energy dissipation systems is a new technology of seismic design researchfield in recent years, it dissipates energy of horizontal earthquake action and wind actionthrough the energy dissipator attached to the structure, so as to achieve the purpose ofseismic.Performance-based seismic design means the maximum deformation structuresgenerated by no more than a pre-set limit(The performance target), though the selection ofreasonable target, it can make the cost of building structure more reasonable. Combined withenergy dissipator and it is used for the idea of performance-based seismic design, this papercombines the two, and conducts some research on unsymmetrical plan.The mechanical characteristics of viscous damper are introduced in this paper, it gives avariety of mechanical model of viscous damper, and makes comparisons between nonlinearviscous dampers and linear viscous dampers, introduces the principle of equivalentlinearization of nonlinear damper. Derivation of the linear viscous damper and nonlinearviscous damper additional damping ratio formula. And carries on the simple introduction tothe other common dampers.Performance-based seismic design about added nonlinear viscous dampers has beenstudied. Introduced direct displacement-based seismic design method about plane symmetricstructure. MDOF system han been transferred to SDOF system, and the total damping ratio ofSDOF to satisfy the effect of specific earthquake wave is calculated through displacementspectrum, this total damping ratio of SDOF can be considered as the damping ratio demand tomeet required performance of the original structure, then the supplemental damping ratio ofdampers are determined, finally, the dampers can be designed. Capacity spectrum method canbe used on unsymmetrical plan structure, establishing the demand curve and capacity curve,the required supplemental damping ratio can be obtained by comparison between targetdisplacement and intersection of the two curves.The mode of distribution in two directions ofstructure has been introduced, the final design of capacity spectrum method is proved throughtime history analyses of three earthquake waves.Calculation method of structure response has been explored, firstly assuming thestructural displacement of top point, the total damping ratio of structure added viscousdampers can be estimated,, establishing the demand curve and capacity curve, comparingbetween intersection of the two curves and the assumed structural displacement of top point,re-assuming structural displacement of top point if comparison result does not close, repeating iterative calculation until top displacement is close to the intersection of demand curve andcapacity curve. The top point displacement of multiple modes can be calculated like this,finally using CQC combination to obtain final structural displacement of the top point. Theproposed method is validated by time history analyses of three earthquake waves.