ANALYTICAL STUDY FOR DUCTILITY EVALUATION SUBJECTED TO SHEAR FAILING R/C COLUMN STRENGTHEND BY CARBON FIBER SHEETS

Carbon fiber sheet (CF sheet) is widely used in seismic strengthening for existing R/C buildings. But shear failure is considered to occur in R/C column even if it is strengthened by CF sheet. In the current seismic retrofit standard, effect of CF sheet is only evaluated if the increasing in ultimate strength is observed. However, some past experimental studies showed the ductility of RC column is improved by CF sheets even if the strength does not increase. This research is aiming to propose the rational evaluation for the improving in ductility of RC column by CF sheets which is failed in shear. FEM analysis was used in this examination, and the followings are obtained. 1) There is upper limitation between the amount of the total shear reinforcement(Σpw • σwy) and the ductility. 2) The improvement in ductility reaches upper limit when the ratio of the total shear reinforcement to upper bound shear strength ((Σpwσwy)/(υ σ B/2)) becomes unity.