Many existing building in korea, constructed according to an out-date standard, were found to be inadequate to withstand major earthquake. Accordingly, significant research effort has been devoted to develop and evaluate different strengthening techniques to increase to seismic resistance of R/C structure. In our previous research[1], the galss fiber sheet and carbon fiber brace system for seismic strengthening was developed. In the study, a three-story R/C building that represent a typical Korean school constructed in 1980s was selected, and its seismic performance before and after strengthening was evaluated based on the seismic capacity evalution method.