International Concrete Abstracts Portal

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.

This article presents the results of a research program on the behavior of masonry walls reinforced with FRP bars subjected to out-of-plane loads. The article also proposes a preliminary protocol for the flexural design of masonry walls reinforced with FRP bars. The objectives of this investigation were: (1) evaluate the flexural behavior of masonry walls reinforced with FRP bars subjected to out-of-plane loads, and (2) develop preliminary design recommendations. Ten masonry walls, 2 m [6.6 ft] high, were subjected to out-of-plane loads, tested under quasi-static loading cycles. The test specimens included walls constructed using concrete and clay masonry units, reinforced with Glass FRP (GFRP) and Carbon FRP (CFRP) bars in different configurations. All the FRPreinforced masonry walls showed a bilinear moment-deflection curve with one steep slope up to cracking of masonry and a decrease in stiffness after cracking. The majority of the walls failed due to crushing of masonry in the compression side. After failure occurred and as the out-of-plane load was progressively removed, the walls returned to a position close to the initial vertical position. In general, the approaches used to calculate flexural strengths and deflections provided good agreement with the experimental results.

Fiber reinforced cementitious matrix (FRCM) composites have gained popularity for strengthening of concrete structures due to their capacity to overcome some drawbacks of fiber reinforced polymer (FRP) composites, mainly related to the use of epoxy resins. Research on the topic has shown that FRCM composites can increase the axial, flexural, shear, and torsional capacity of concrete elements. However, experimental studies are still limited, and an important effort is required to develop accurate and reliable design models to predict the contribution of the system to the capacity of strengthened elements. In this paper, a quantitative review of experimental studies of axially loaded concrete elements confined with FRCM composites is presented. The influence of selected variables on the increase in axial capacity of the strengthened specimens is evaluated. Three available design models for predicting the increase in axial capacity of FRCM-strengthened concrete are assessed using a database compiled by the authors. Results show that confinement with FRCM composites can provide a significant increase in axial strength for both cylindrical and prismatic concrete specimens. Further efforts are needed to improve the performance of models to predict the axial strength and behavior of FRCM-confined concrete.

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.