Research On Behavior Of Eccentrically Braced Structures Installing Viscoelastic Damper

There are two systems of conventional tall steel buildings: moment-resisting frames and concentrically braced frames.Moment-resisting frames have good inelastic behavior and are easy in interior planning thanks to being without obstacle between columns. Being with great flexibility, however, it is not economical to meet the inter story drift limit when the building is high. Concentrically braced frames can provide high elastic stiffhess and are widely used. But the buckling of the brace can make the capacity drop.Eccentrically braced frames have the advantages of both moment-resisting frames and concentrically braced frames. This system can provide high elastic stiffness and large inelastic energy dissipation capacity in resisting lateral loads caused by seismic activity. But after the strong ground motion, every story of this system can appear great inelastic deformation so that this structural system sacrifices the main beam, although the structure avoids collapsing. The structure needs lots of restoration or replacement. And for active link fully developing its capacity of deforming, the load-carrying capacity of brace and column must be great so that brace and column don't yield before active link is up to the ultimate load-carrying capacity. So the sections of column and brace are enough huge. As a result, economic efficiency is not good enough.Through analysing the advantages and disadvantages of the eccentrically braced frames, The author has the thought that viscoelastic dampers are serially connected with brace in eccentrically braced frames. The author calls this kind of frames as energy dissipation eccentrically braced frames, having the function of "double fuse". But whether can this structure meet the thought ? This paper compares the internal force, displacement and relative displacement of eccentrically braced frames and energy dissipation eccentrically braced frames under the intensity of frequently occurred earthquake and intensity of seldomly occurred earthquake through an example and reflects the energy dissipationeccentrically braced frames having the better earthquake resistant behavior.Through the non-linear time-history analysis and arranging and analysing the conclusion, the displacement relative displacement and internal force of energy dissipation eccentrically braced frames are all reduced. And they have different changes under different seismic waves. Under El-Centro wave, the axial force of columns in story 1 and story2 increases a few.From an example of energy dissipation eccentrically braced structure of simple free degree, the author researches the fundamental principle and earthquake-response analysis of energy dissipation. In this paper, design thinking of energy dissipation eccentrical brace is presented. The whole design process is obtained in an example and its result is satisfying.