Experimental investigation of the mechanical connection between FRP laminates and concrete

This paper presents the results of an experimental campaign aimed at investigating the interfacial behavior of Fiber Reinforced Polymer (FRP) laminates Mechanically Fastened (MF) to concrete members.The experimental program includes 34 direct shear tests (DSTs) performed on FRP laminates fastened to concrete prisms through either single or multiple screwed anchors arranged according to different layouts.In 17 tests a steel washer was interposed between the head of each fastener and the outer side of the laminate; in the remaining ones, instead, no washer was used.The performed tests allowed to evaluate the behavior of the MF-FRP connections mainly in terms of load-carrying capacity, FRP strain distribution and damage mechanism; the influence on the experimental response of both fastener configuration and washer presence was also investigated.Results of tests on specimens fastened by using a single screw were used for calibrating a possible force–displacement law to describe the interaction between MF-FRP laminate and concrete substrate.Finally, simplified FEM models were implemented and verified for better simulating the experimental results and estimating the strain and stress distributions within the laminate.