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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.

The ACI440.2R document represents state-of-the-art design and construction guidelines for the strengthening of concrete structures using externally bonded FRP systems. A significant number of FRP field applications are related to seismic strengthening of existing reinforced concrete structures. The 2008 edition of ACI440.2R does not provide design guidance for the use of FRP in seismic applications. As such, ACI Committee 440 has developed seismic guidelines for inclusion in the newly released 2017 edition. The new seismic design guidelines include the most common applications observed in the industry, such as confinement of beam and column sections, as well as flexural and shear strengthening of concrete members. Since seismic retrofit can be based on a variety of codes and standards, these guidelines are intended to be compatible with the selected code or standard. The seismic guidelines are incorporated in a separate chapter within the ACI440.2R document but, where applicable, reference other chapters for design provisions. This paper summarizes common deficiencies found in existing reinforced concrete buildings and the mitigation of some of these deficiencies using FRP and the provisions of the 2017 edition of ACI 440.2R.

In order to establish a numerical analysis method to provide an improved estimate of the dynamic response characteristics of reinforced concrete (RC) beams strengthened with near-surface mounted (NSM) Aramid FRP (AFRP) rods under impact loading, a method using fictitious tensile strength of the concrete elements based on an equivalent tensile fracture energy concept (Gf) was proposed. Applying this concept for the concrete elements, an elasto-plastic dynamic response analysis of the RC beams under impact loading was carried out using a fine mesh for a more accurate evaluation of the crack patterns and for a more realistic consideration of the strengthening effects of AFRP rods. The applicability of the method was investigated comparing with the experimental results. Here, configurations of the time histories of the impact force, the reaction force, the mid-span deflection, and crack patterns occurred in the RC beams were used for this investigation. From this study, it was seen that the RC beams strengthened with NSM AFRP rods under falling-weight impact loading can be better simulated using fine meshes with fictitious tensile strength for concrete elements following proposed Gf concept. Here, the case of using a fine mesh having a length of about 6 mm gave appropriate results.

Structural retrofitting of flat slabs is often required mainly due to corrosion of reinforcement, change of use and design errors. Punching shear failure is a common type of failure in flat slabs in the area of connection with the column, which could lead to progressive collapse. The slab-column connection is critical as it exposes to bending moments and significant shear stresses in RC flat slabs. Utilization of FRP attachment as strengthening method for concrete structures is becoming the most popular approach for improving their characteristics. CFRP laminates are already well established structural strengthening material and the further optimisation of their application in case of punching shear strengthening will allow for developing of effective solution for this problem. The research comprises testing of seven small scale reinforced concrete slabs (550x550x75 mm) (21.7x21.7x3 inch) with a column stud (80x80x75 mm) (3.1x3.1x3 inch) at the centre to simulate the slab-column connection. One control sample and six CFRP strengthened samples were prepared and tested against punching shear failure. The primary variable of the experiment was the positioning, layout and configuration of the CFRP laminates. The total width and thickness of the CFRP laminates were kept constant and the objective was to determine the most efficient layout. It was found out that using CFRP laminates as externally bonded reinforcement significantly enhances the punching shear capacity and results in improved stiffness of the slabs. The result shows a significant increase in ultimate load and stiffness.

The use of Externally Bonded Fiber Reinforced Polymer (EBR-FRP) systems is an established technique for the structural improvement of existing buildings but the technique features disadvantages. Premature FRP-to-concrete debonding has been commonly highlighted as one of the main problems, together with the difficulty of fully wrapping the structural element when the structure presents complex geometries. FRP straight anchors are used to transfer the forces from the FRP sheet into the structural element, ameliorating these two problems, but a comprehensive design method for FRP anchors has not yet been established despite the increased use and research attention given to FRP anchors. A research project was undertaken involving monotonically testing single-anchors in tension to investigate the behavior and capacity of isolated FRP anchors. However, a number of factors that may have a significant influence on the capacity of the anchors could not be investigated such as the behavior of the anchors when subjected to tension-compression cycles and the effect of dynamic loads. To address some of the aspects not covered within the single-anchor tests, six full-scale reinforced concrete columns were tested using pseudo-static loading, with the aim being to verify that the peak moment developed during testing was forecasted accurately.