| Reinforced concrete frame(RC frame)is the most commonly adopted structure system,which existed substantially in the area subjected to seismic activities.Some phenomena caused by seismic excitation can be seen,such as concrete cracking,local damage as well as residual deformation.However,not whole structure are damaged severely,since that only some stories are damaged badly.It will cost greatly to dismantle the whole structure after earthquake and highlight the problem of construction refuse disposal.Consequently,in this paper,the retrofitting design method of “combination of buckling-restrained braces(BRB)for strengthening and prestressed steel strip for retrofitting” is proposed,the earthquake-damaged RC frame structure retrofitted with this method can recover or even exceed the previous seismic performance and meet the requirement of seismic design.This retrofitting method can employ full benefits of structural components,reduce economic loss,construction refuse and resource waste,and accelerate recovery procedure after earthquake.In this paper,two experimental researches on the scaled RC frame of 1:2,one undamaged and the other earthquake-damaged,were conducted.First at all,low-cyclic pseudo static test of the reinforced concrete frame with single span and three stories was conducted and then retrofitted the damaged structure with BRBs to simulate the earthquake-damaged structure.The test on the earthquake-damaged structure was conducted again to investigate the seismic performance.Compared with the contrast test,the failure process,yield mechanism,failure mode were observed and seismic index such as hysteretic curve,skeleton curve,bearing capacity,deformability,ductility,energy-dissipation capacity,stiffness degradation and so on,were analyzed in detail.when the bearing capacity was dropped to 85% of the ultimate load bearing capacity,test ended.The results indicated that,of earthquake-damaged structure,BRBs served as the first seismic defensive line and could yielded prior to the main structure to dissipate a great deal of input energy,protecting the main structure,so the installation of BRBs could retrofit earthquake-damaged RC frame effectively.Furthermore,the shear force of beam-column joint of RC frame with BRBs was analyzed theoretically,and the influence factors of earthquake-damaged beam-column joint’s shear capacity were analyzed.Then,the calculation formula of shear capacity and relative design recommendation and method of beam-column joint of retrofitted earthquake-damaged frame were proposed. |
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