Study On The Retrofitting Technology Of Existing RC Frame For Self-centering Performance

The RC frames are usually damaged severely during an earthquake.They show story failure mechanism,which causes that seismic behaviors can't be fully utilized.A lot of RC frames can't continue to be used and have to be pushed over because of large residual deformation,which causes the interruption of buildings' function.Therefore,it is very important to viod story failure mechanism of the RC frame and reduce the residual deformation of structure.Earthquake resilient structure is a new seismic structure,including rocking structure,self-centering structure and replaceable structure.Most of existing RC frames don't have self-centering ability.In view of this situation,A method to retrofit them for the self-centering ability,self-centering energy dissipation light rocking steel frame(EDLRF)is proposed.By this method,RC frame will have self-centering ability and better seismic behaviors,voiding story failure mechanism.According to this method,the main research contents:(1)An important component of EDLRF,self-centering energy dissipative brace(SCED)is introduced,including concept,structure,mechanism under axial force,axial stiffness formula of each stage.(2)The existing six-story RC frame located in Northwest area of China is taken as an example.According to the RC frame(the basic structure),the rocking frame(the substructure)and SCED are designed.According to the design results,the element and material are selected,constitutive parameters of material are calculated.OpenSEES is adopted to model the basic structure,rocking frame and EDLRF.(3)The pushover analysis is carried out for the RC frame,the rocking frame and the EDLRF,and the seismic bearing capacity of the three kinds of structures are compared.Based on the capacity spectrum method,the seismic behaviors of the RCframe,the rocking frame and the EDLRF are analyzed.The RC frame,the EDLRF are analysed by time history analysis.According to performance based seismic design,the seismic behaviors level are evaluated.(4)The residual displacement and the residual story drift are compared between the RC frame and the EDLRF.The self-centering ability of EDLRF is analyzed.Hysteretic curves of SCED in the 8(0.2g)and 8(0.3g)seismic intensity are compared.Self-centerting ability and energy dissipation of SCED are analyzed.The study results show: the method to add EDLRF can improve the seismic bearing capacity of RC frame.The RC frame shows global yield mechanism rather than story failure mechanism.The displacement of RC frame is reduced remarkably.The seismic performance level is also improved.The residual displacement and the residual story drift are reduced,so the RC frame has good self-centering behavior.The hysteretic curve of SCED is double banners,showing good energy dissipation and self-centering behavior.