Fiber-reinforced polymer (FRP) composite materials been widely used in civil engineering new construction and repair of structures due to their superior properties. 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 reports, guides, and specifications on the use of FRP materials for may reinforcement applications 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.

This volume represents the thirteen in the symposium series and could not have been put together without the help, dedication, cooperation, and assistance of many volunteers and ACI staff members. First, we would like to thank the authors for meeting our various deadlines for submission, providing an opportunity for FRPRCS-13 to showcase the most current work possible at the symposium. Second, the International Scientific Steering Committee, consisting of many distinguished international researchers, including chairs of past FRPRCS symposia, many distinguished reviewers and members of the ACI Committee 440 who volunteered their time and carefully evaluated and thoroughly reviewed the technical papers, and whose input and advice have been a contributing factor to the success of this volume.

In design of structures, both the ultimate limit state (ULS) and the serviceability limit state of the structure must be verified. Carbon fiber reinforced polymer (CFRP) materials have high strength, and large amounts of CFRP are not needed for ULS. On the other hand, CFRP may be needed to introduce enough stiffness for meeting the serviceability design criteria and reduce the crack of concrete. The effects of externally bonded composite plates on the mechanical behavior of a cracked RC beam, loaded in flexure, are obtained by an experimental approach. The problem of crack width prediction is addressed. The model values are compared to experimental data obtained using a digital image correlation method. The crack width and spacing is measured as a function of load to analyze crack propagation. Finally, the study focuses on the validation of the codes model for calculating crack widths and curvatures in strengthened beams.

This paper presents an extensive experimental study of the effect that the surface profile has on the bond behavior of FRP bars in concrete. Studied parameters include: concrete strength (~35 MPa (5075 psi) and ~66 MPa (9570 psi)), test type (pull-out, direct tension pull-out and beam pull-out) and surface profile of the FRP bar (helically wrapped, indented, two types of sand coated and two types of helically wrapped and sand coated. For comparison, ribbed steel bars were also used). It was found that the bond strength can vary considerably when different finishing of the same surface profile type are used (e.g., fine and rough sand coating) and that the concrete strength does influence the bond strength even if it is higher than the limit (~30 MPa (4350 psi)) stated in literature. Furthermore, the bond strength results of all FRP bars were consistently higher than those of steel bars. The highest slip value to reach the bond strength was observed for helically wrapped FRP bars, and the lowest for sand coated bars. Finally, the test setup was found to affect the bond strength, while no significant effect of bar diameter was observed in the results.

This paper summarizes the state-of-the-art on the topic of structural wall panels strengthened using fabric reinforced cementitious matrix composites (FRCM) composites. A systematic review of the literature is carried out to identify gaps in the available literature. A database of experimental tests, relevant for structural panels, was created and used to assess the influence of parameters such as test method, fiber type and material compressive strength, on the performance of FRCM strengthening. Since experimental investigations on walls strengthened with FRCM composites is still limited and mostly focused on shear, further investigations on walls as compression members can be considered timely, especially walls with openings, which have been overlooked. Experimental tests performed by the authors on reinforced concrete walls with openings are presented and assessed relative to the complete database. It was shown that FRCM composites are suitable repair solutions when new openings need to be created in existing walls.

In recent research, the use of the near-surface mounted (NSM) technique has been proven to increase the torsional strength of reinforced concrete (RC) members. In this paper, an investigation into the torsional deformation characteristics of the ten RC beams strengthened using the NSM technique is reported and evaluated using photogrammetry. The experimental results of two control beams and eight beams strengthened using CFRP laminate embedded into pre-cut grooves using epoxy and mortar are evaluated. The Digital Image Correlation Photogrammetry (DIC) is used to determine the three-dimensional displacement of targets placed on the north and south faces of the beams at selected load levels up to failure. The main aim of this study was to measure the propagation of torsional crack width with increasing torque for each beam. The torsional deformations of the beams are evaluated and verified with the photogrammetry measurements and the differences in the width of the large torsional cracks across the tested beams are highlighted and compared. The width of the torsional cracks for the strengthened beams was smaller than that that of the control beams at the same load level. Similar deformation mechanisms were observed for the strengthened and control beams.