REHABILITATION OF R. C. BEAMS FAILING IN SHEAR

Abstract

In last few decades lot of attempts in India and abroad have been made to study the strengthening problems of R.C. structural components. It is seen that in majority of cases, use of steel plate bonding techniques to the sides of the distressed member have been tried by several research workers with success. It is, however, to be seen whether steel plates can be effectively replaced by a layer of ferrocement. The present investigation deals with two objectives in view, one of which was to study the use and performance of ferrocement in strengthening beams in shear distress and secondly to investigate the relative efficacy of different bonding media used in bonding pre-cast ferrocement plates to the R.C. beams. The reinforced concrete beam specimens were tested to failure in shear. The same beams were rehabilitated by pre-cast ferrocement plates with different bonding media to the sides of the beams in five categories. The experimental results showed 20.50%, 19.40%, 35.02% and 24.80% increase in strength over the original beams strengthened with precast ferrocement plates bonded with "Epoxy bonding medium", "Bolting without medium", "Epoxy bonding medium with bolting" and "Cement-sand mortar bonding medium with bolting" respectively. However, cement-sand mortar bonding medium was found to be ineffective as it did not improve strength. This study showed that the shear strengthening with ferrocement can substantially increase their stiffness, reduce deflection, cracking and structural deformation. Provided the bonding medium is chosen carefully, the rehabilitated beams show beam action and composite behaviour right upto failure.