Effects of freeze-thaw cycling on anchorage of fibre-reinforced polymer sheets bonded to reinforced concrete beams.

摘要

The flexural and shear strengthening of reinforced concrete beams by the external bonding of composite plates and sheets is rapidly becoming a repair and rehabilitation technique of choice in the civil engineering industry. A wide variety of research has shown the technique to be economical, easily applied, and very effective. There are, however, a number of concerns related to the durability of this repair technique, especially in cold climates such as those found in Canada. This thesis presents the results of an experimental and theoretical investigation into the effects of freeze-thaw cycling, specifically on the composite-concrete bond. The results of flexural tests on a total of 42 small-scale flexural beams, reinforced in tension with externally bonded fibre reinforced polymer sheets and plates, are presented and discussed. Comparison between beams subjected to varying numbers of freeze-thaw cycles and plated with different composite materials indicates that little if any damage to the composite-concrete bond results from freeze-thaw cycling. Analytical methods for failure load prediction are presented and discussed, and a simple analytical model is developed that can be used to predict bond strains and stresses in the composite-concrete joint. An extension of the analytical model is used to derive expressions that predict the potential for bond damage with any variation in temperature for a given concrete-composite joint length.