Evaluation Of Seismic Performance For Unsymmetric-plan Buildings With Viscoelastic Dampers

Following the fast development of high-rise, there have appeared a large of irregularbuildings in pursuit of the type and function diversity Because the mass and the stiffnesscenter does not coincide, structure will produce large torsion under earthquake, in some caseseven become the main factors that lead to the destruction of buildings. With the developmentof the structure control theory, the application of energy dissipated technology will be moreand more popular, the combined between energy dissipated technology andperformance-based seismic design has gradually become important, but most of it is for theplane symmetric structure, the study of plane asymmetric structure is relatively less,researchers only verify that energy dissipation device can effectively reduce the torsionresponse of structures through experiments, but the relevant design theory is less. For thoseexisting problems, the research work of this paper is done in below parts：(1) The first important question is the pushover analysis of plane asymmetric structurewith energy dissipation device. Because of the influence of torsion model and higher model,the deformation of asymmetric structure is more complex. According to the theory of Choprastructural dynamics, with considering the torsion model and higher model and the additionaleffect of damper stiffness, the pushover analysis will use two "modal" pushover analysis toget the pushover curve. The fundamental model include the first translation model and thefirst torsion model, the residual model is mainly transformed from the first translation model.(2) Considering the changes of the period and model in the structure before and afterstructure yield, this paper will calculate viscoelastic damper，s damping ratio in the structurebefore and after structure yield, after that it will be extended to the asymmetric plan structure.According to the definitions of the fundamental mode and residual mode, the constantassumed that the structure of damper and the yield of mode shape, the damping ratio ofdamper under residual model will be calculated.(3) Based on Chopra modal pushover analysis theory, using capacity spectrum method tocalculate performance point. The first step is to determine the performance objectives, afterthat the assessment of the seismic performance of the original structure by using capacityspectrum method will be done, if it is not meeting performance objectives, now it will be adding energy dissipation device, the seismic performance of the structure with dissipationdevice will be calculate by two "modal" pushover analysis method, using the capacityspectrum method to determine the performance point of each "mode", the reaction of thestructure will be calculated by SRSS or CQC rule. Finally, the evaluation of the accuracy ofthis method will be done by compared with the results of nonlinear dynamic analysis.