Shear strengthening of high strength lightweight SCC beams internally reinforced with GFRP bars and external CFRP strips

Abstract

Last few years have seen a substantial growth in the development and application of lightweight concrete (LWC) due to its enhanced mechanical properties and economic benefits in comparison to conventional normal weight concrete (NWC). The use of LWC in infrastructure has been popularised, especially in long-span bridges and high-rise bridges due to its lower density, which significantly reduces the dead load on the structure. Carbon fibre reinforced polymers (CFRP) and glass fibre reinforced polymers (GFRP) have rapidly gained acceptance in the infrastructure industry for their desirable characteristics over traditional steel. Extensive experimental research has been carried out over to years to investigate the shear performance of externally strengthened NWC beams with CFRP (carbon fibre reinforced polymer) strips. However, very limited research has been conducted on the shear performance of GFRP reinforced LWC beams externally strengthened with CFRP strips. Therefore, the main objective of this experimental study is to investigate the shear performance of high strength lightweight self-compacting concrete (HLWSCC) beams reinforced with internal GFRP bars and strengthened with external CFRP strips. HLWSCC is the latest development in concrete technology that combines the benefit of LWC and self-compacting concrete (SCC). One control specimen and two shear deficient HLSCC beams were strengthened with CFRP strips in the shear span. The test variable studied was the strip orientation (u-wrap and 45°) and all beams subjected to static four-point bending test. Load-deflection response and failure modes were observed and recorded for all the tested specimen. CFRP strips has considerably increase the load carrying capacity of HLWSCC strengthened beam specimen. The percentage increase in nominal shear strength ranged from 58.7% to 73.4% over unstrengthened control specimen.