The use of Fiber-reinforced polymer (FRP) composite materials in new construction and repair of concrete structures has been growing rapidly in recent years. FRP provides options and benefits not available using traditional materials. The promise of FRP materials lies in their high-strength, lightweight, noncorrosive, nonconducting, and nonmagnetic properties. ACI Committee 440 has published several guides providing recommendations for the use of FRP materials based on available test data, technical reports, and field applications. The aim of these document is to help practitioners implement FRP technology while providing testimony that design and construction with FRP materials systems is rapidly moving from emerging to mainstream technology.

A commonly reported failure mode through experimentation of fibre-reinforced polymer (FRP)-concrete bonded interfaces is premature debonding of the FRP. Such undesirable failure can occur at strains significantly lower than the strain capacity of the FRP and it can be sudden. Anchorage of the FRP is an intuitive means to delay and even halt debonding, and the addition of anchors can also lead to more deformable FRP-strengthened elements. The so-called FRP anchor has been shown to be an effective anchorage device and while there have been several experimental studies reported to date on FRP-strengthened RC elements anchored with such anchors, there has been decidedly less research on numerical modelling. This paper presents the details of a partial interaction model and a constitutive model for the FRP-to-concrete bonded interface as well as FRP anchors. The models are then used to simulate FRP anchors in single-shear FRP-to-concrete joints. The results of parametric studies on key variables such as plate geometry and plate material properties as well as anchor location and number of anchors are then provided. The parametric studies enable insights to be gained towards the contribution of FRP anchors in FRP-to-concrete bonded interfaces.

The development of fiber composite materials (FRPs) and their application to structural elements as externally bonded reinforcement is an effective means to increase the strength of existing bridge girders in flexure, shear and torsion. Despite the high strength of FRP materials, premature debonding of the FRP from the concrete substrate typically occurs well before the ultimate tensile strength of the material is reached. Recent research has found that the introduction of end anchorage systems such as bidirectional fiber patch anchors has been found to counteract the end peeling and interfacial shear stresses that occur at fiber ends, resulting in much higher material utilisation prior to debond. However, all of the research conducted on patch anchors to date has been based on near-end supported single shear pull tests and the performance of patch anchors when applied to large-scale beams remains to be investigated. The paper presents a finite element analysis of a large-scale bulb T beam which was calibrated using experimental results from the literature. The calibrated model was later modified by the addition of FRP shear strengthening and the inclusion of bidirectional fiber patch anchors which were found to significantly enhance the maximum laminate strains attained prior to beam failure.

The bond between external fiber reinforced polymer (FRP) reinforcement and concrete substrate is of critical importance for the effectiveness of this strengthening technology. As a result, the design of reinforced concrete (RC) members strengthened with FRP composites is to account for, among other failure modes, the debonding of the laminate from the substrate. Although analytical and experimental research conducted for over two decades has led to archival publications and guides, no standard test methodology is yet available for shear bond strength evaluation after aggressive environmental conditioning.

This paper aims at studying the durability of the bond strength between carbon FRP (CFRP) laminate and concrete substrate. The set-up consists of a small, plain concrete beam reinforced with an externally-bonded CFRP laminate that is tested under three-point bending. The force that the CFRP laminate can bear before detaching is easily calculated and the effect of accelerated conditioning is thus evaluated. Different environments and times of exposure are considered including 100% relative humidity, saltwater, alkali solution and dry heat. Statistical analysis are carried out to obtain statistical evidence on the effect of both the conditioning environment and the time of exposure on shear bond strength. The test methodology used in this work has the attributes of an effective standard.

This work presents an experimental investigation of composite girders consisting of precast Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) slabs placed on pultruded Fiber-Reinforced Polymer (FRP) Igirders. Two control girder specimens and seven large-scale composite girders were tested under static four-point bending. Two series of the FRP-UHPFRC composite girders were examined. H-series girders composed of hybrid carbon/glass FRP (HFRP) I-girders topped with either full-length precast UHPFRC slabs or segmental counterparts. G-series girders included segmental UHPFRC slabs placed on glass-fiber-reinforced polymer (GFRP) I-girders. Twelve precast UHPFRC segments were used in each slab of the segmental composite girders. Either high-strength mortar or epoxy adhesive were used to join the precast UHPFRC segments. The test results revealed that the flexural stiffness of the composite girder with the epoxy-connected segmental precast slabs is almost identical to that of the full-length precast composite girder. The mortar-connected girder exhibited slightly more ductile behavior than the epoxy-connected girder. The G-series girder with thick GFRP plate externally bonded to the soffit of the GFRP Igirder showed pseudo-ductile behavior. All the composite girders demonstrated significant improvements in flexural stiffness and moment-carrying capacity compared with the control FRP I-girders without the UHPFRC slabs.