Flexural retrofitting of RC beams using external bars at soffit level – An experimental study

Abstract

Throughout the globe, huge stock of buildings become vulnerable to damage due to aging, rebar corrosion, and natural hazards, particularly earthquake. Section enlargement, bonded steel plating, external post-tensioning and FRP composites wrapping are some of the techniques being widely followed to retrofit various structural elements. Each technique has at least one or more number of limitations. High cost, difficulty in execution, reduction in headroom, loss of aesthetic value, increase in self-weight, careful surface preparation, de-bonding failure are some of the innate limitations of these techniques. A maiden attempt has been made by the authors to devise a new technique to retrofit RC beams with external reinforcement. The proposed method overcomes most of the drawbacks of the above said existing methods. Some work has already been reported on external reinforcement by keeping the reinforcement at the sides of the beam using deflectors, mechanical anchoring devices and strengthening end anchorage zones. The reported technique in the present work overcomes all the drawbacks of the above method. The authors propose the external bars to be kept at the soffit level of the beam section, thus eliminating the use of deflectors, mechanical anchoring devices and making it amenable, simple and effective. Additional advantages of the present technique are the enhanced moment carrying capacity, reduced deflection and crack width and improved ductility.