An experimental study of the influence of plate end anchorage of carbon fibre composite plates used to strengthen reinforced concrete beams

摘要

Carbon fibre reinforced polymer (CFRP) materials are well suited to the rehabilitation of civil engineering structures due to their corrosion resistance, high strength-to-weight ratio and high stiffness-to-weight ratio. Their application in the field of strengthening is envisaged to expand due to the vast number of bridges and buildings in need of strengthening. In order to apply these materials effectively, it is necessary to understand the behaviour of members strengthened with externally bonded composite plates, one aspect of which is the response to the installation of anchorage at the ends of the plates to resist plate separation from the beam. A number of 1.0 m long plated beams were tested in four point bending and as cantilevers to demonstrate that the structural benefit of plate end anchorage diminishes as the shear span/depth ratio of the beam increases. Under a low shear span/depth ratio (3.00 in the present work), the anchorage improves the composite action between the plate and the beam, giving rise to greater structural stiffness after yield of the internal rebars. This beneficial influence can be achieved using a bolted anchorage system which provides the same improvement in composite action as a large plate end clamping force generated by trapping the plate under the beam supports. Although the plate end anchorage has most structural benefit under a low shear span/depth ratio, it is recommended that anchorage be applied in every case until long term practical experience suggests otherwise.