The most recent report by ACI Committee 440 on externally bonded fiber reinforced polymer (FRP) strengthening systems states that systems designed to mechanically anchor FRP should be studied in detail and substantiated by physical testing. To select and design an appropriate anchorage system for use in an FRP strengthening system, it is important that findings from previous research studies be known. This paper presents a comprehensive literature review of the performance of different mechanical anchorage systems used in FRP strengthening applications. Each anchorage system is discussed in terms of its purpose and performance. Advantages and disadvantages of each system are discussed, and areas in need of future research are explored.

Rapid and effective repair methods are desired to enable quick reopening of damaged bridges after an earthquake occurs, especially for those bridges that are critical for emergency response and other essential functions. This paper presents results of tests conducted as a proof-of-concept in the effectiveness of a proposed method using externally bonded carbon fiber reinforced polymer (CFRP) composites to rapidly repair severely damaged RC columns with different damage conditions. The experimental work included five large-scale severely damaged square RC columns with the same geometry and material properties but with different damage conditions due to different loading combinations of bending, shear, and torsion in the previous tests. Over a three-day period, each column was repaired and retested under the same loading combination as the corresponding original column. Quickset repair mortar was used to replace the removed loose concrete. Without any treatment to damaged reinforcing bars, longitudinal and transverse CFRP sheets were externally bonded to the prepared surface to restore the column strength. Measured data were analyzed to investigate the performance of the repaired columns compared to the corresponding original column responses. It was concluded that the technique can be successful for severely damaged columns with damage to the concrete and transverse reinforcement. For severely damaged columns with damaged longitudinal reinforcement, the technique was found to be successful if the damaged longitudinal reinforcement is able to provide tensile resistance, or if the damage is located at a section where longitudinal CFRP strength can be developed.

The shear strength of reinforced concrete (RC) elements can be improved by applying externally bonded (EB) fiber-reinforced cementitious matrix (FRCM) composites. FRCM composites are generally U-wrapped around the cross-section of RC beams and completely wrapped around the cross-section of RC columns. When the U-wrapped layout is employed, composite debonding usually occurs before the tensile strength of the composite can be attained. However, depending on the specific FRCM adopted, different failure modes can be observed. Although the use of FRCM composites to strengthen existing RC members is gaining popularity, limited work has been done to formulate a reliable design procedure for FRCM shear strengthening of RC members. In this paper, a model is proposed to compute the shear strength contribution of FRCM composite U-wrapped around RC members. The model, which is an extension of the model used for fiber-reinforced polymer (FRP) shear strengthened beams, is based on mechanical considerations, does not contain empirical coefficients, and can be applied to any FRCM composite provided that the bond behavior and tensile strength are identified. The model is validated by comparing the analytical predictions with the experimental results of RC beams strengthened in shear with polyparaphenylene benzobisoxazole (PBO) and carbon FRCM composites found in the literature. Finally, an example of the evaluation of the shear capacity associated with the FRCM reinforcement is provided to illustrate the use of the model.

In this study, a new type of composite comprised of steel cords embedded in a mortar matrix—referred to as steel-reinforced grout (SRG)—is explored for use in the confinement of masonry columns. This paper presents the results of an experimental study carried out to understand the behavior of solid clay brick masonry columns confined by single-layer SRG jackets. Thirty-one confined and three unconfined columns with a square cross-section were tested to failure under a monotonic concentric compressive load. Test parameters considered were the SRG matrix type, column corner condition, and steel cord sheet density (i.e., steel cord spacing) in the SRG jacket. SRG confinement improved the compressive strength, ultimate strain, and energy absorption of masonry columns relative to the unconfined condition. Models from the literature for FRP-confined masonry were examined for their applicability to predict the strength increase from the SRG jacket, with certain models predicting the confined compressive strength within 9% of the test values.