Study On Flexural Behavior Of Steel Reinforced Concrete Slabs Strengthened With FRP Sheet

Strengthening concrete structure with Fiber Reinforced Polymer Plastic (FRP) sheet is a new structural repair method emerged in the developed countries since 1990s. Carbon fiber reinforced Plastic (CFRP) sheet and Glass Fiber Reinforced Plastic (GFRP) sheet are used the most widely. Because of its lightweight, high-strength, excellent corrosion and fatigue resistance, and nonmagnetic, the method has been used in the strengthening of existing structures, and found to be economical and efficient for application.Based on the experiment of 10 steel reinforced concrete slabs with size of 500mm×100mm×2000mm, the flexural behavior of sluice bridge deck strengthened with GFRP sheet or CFRP sheet is imitated to study. The main contents are as follows:(1)The influences of strengthening quantity and manners, species, the mixing of steel fiber on cracking and ultimate load of slabs are studied. It is shown that the cracking and ultimate load are increased significantly with the quantity of FRP sheet strengthened with; the strengthening effect is better when the layer number of FRP sheet is single than double, while the strengthening quantity is the same; the cracking and ultimate load are larger when the slabs strengthened with CFRP sheet than with GFRP sheet; the cracking and ultimate load are increased significantly when the slabs are reinforced by steel fiber, but the effect of the volume fraction of steel fiber is not obvious.(2)The influences of strengthening quantity and manners, species, the mixing of steel fiber on short-term stiffness of slabs are studied. It is shown that the short-term stiffness is improved obviously with the increase of strengthening quantity of FRP sheet strengthened with; there is no influence of the layer number of FRP sheet on the short-term stiffness, while the strengthening quantity is the same; the short-term stiffness is improved obviously is greater when the slabs strengthened with CFRP sheet than with GFRP sheet; and there is no influence of the mixing of steel fiber on the short-term stiffness.(3)Compared with the experimental results, a lot of problems of the calculating method in current codes were found. The calculating formulas of normal section bearing capacity of reinforced concrete slabs strengthened with FRP sheet are proposed, according to the basic flexural theory based on the plane section assumption.