Influence of FRP width-to-spacing ratio on bond performance of externally bonded FRP systems on one way concrete slabs

摘要

Debonding of externally bonded fiber reinforced polymer (FRP) composite materials used for repair of reinforced concrete elements is commonly observed and is often the critical limit state for such systems. The FRP geometry, as quantified by the ratio of FRP width-to-substrate width, bf/b, (or FRP width-to-FRP spacing, bf/s, for slabs) is expected to affect the ultimate bond performance. Factors accounting for this effect are included in many design guides. An experimental program using concrete slab specimens having identical reinforcement ratios, strengthened with CFRP strips having different bf/s ratios is reported. The focus of the study is the strain in the CFRP and its eventual debonding. Thinner (lower bf/s) CFRP strip are observed to have greater strains at a given load level and to have a higher strain at debonding. The effect of the transverse strain gradient in the CFRP - the CFRP "edge effect" - is also investigated.