RETROFITTING OF CONCRETE CIRCULAR COLUMNS USING CFRP

Structures of architectural importance present a number of challenges in restoration and retrofit, which limit the application of modern codes and building standards. Recommendations are desirable and necessary to ensure rational methods of analysis and repair methods appropriate to the cultural context. Retrofit specifically aims to enhance the structural capacities (strength, stiffness, ductility, stability and integrity) of a building that is found to be deficient or vulnerable. In the specific context of enhancing the resistance of a vulnerable building to earthquakes, the term seismic retrofit is used. The building need not be deteriorated or damaged. The retrofit is intended to mitigate the effect of a future earthquake. This paper is an attempt to show how retrofitting increases the strength of concrete columns. It is essential to identify the deficiencies in a building before undertaking retrofitting measures. Identification of the deficiencies is also expected to create awareness for future construction. For experimental purpose, the sizes of the testing specimens are scaled down to one-fourth the size of a standard reinforced concrete column. Nine concrete specimens of the scaled dimension are cast and cured. The specimens are cast in PVC moulds (cut longitudinally for convenience during removal of specimens). Post curing, retrofitting is carried out using epoxy primer. Three concrete specimens are retrofitted at their centers, three at their ends and the other three are not retrofitted. The retrofitted specimens are dried for a day. Initially, these retrofitted concrete specimens are subjected to non-destructive testing i.e., rebound hammer test and their values are observed. Subsequently, these specimens are tested for their ultimate strength using a universal testing machine and the values for the corresponding cases are observed. The cracking patterns are observed and the variation in ultimate strengths due to retrofitting are studied and reported