Flexural Strengthening of RC Beams with Lap Splices

Abstract

This paper presents results from an experimental study on the external strengthening of reinforced concrete beams having lap splice length less than that recommended by codes of practice for flexural tensile reinforcement. Six reinforced concrete beams having the same dimensions and reinforcement were considered in the experimental program. Firstly, two control beams were tested. The first control beam was made without any splice in the flexural tensile reinforcement whereas the second one had a mid span lap splice with a length of 240 mm which represents20 times the bar diameter. The other four beams had splices with length as that provided for the second control beam. These four beams were considered in order to investigate four different external strengthening techniques for beams having insufficient lap splice length compared as recommended by codes of practice. The external strengthening techniques included the use of near-surface mounted (NSM) bars or external bonding plates. Both carbon fiber bars and deformed steel bars were considered for the NSM technique. The external bonding plates included the use of carbon fiber laminate and anchored steel plate. The experimental results showed that all the techniques considered successfully restored more than the flexural capacity of the control beam without splice but with different ductility levels and different modes of failure. Also, an improvement in the beams stiffness was observed
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