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.

Various techniques have been developed and applied to strengthen deteriorated RC (Reinforced Concrete) structures such as the EBR (Externally Bonded Reinforcements) and NSM (Near Surface Mounted) systems. However, NSM still suffers premature failure like EBR. Recent research tried to prestress the NSM but the prestressed NSM needs a special prestressing system. Accordingly, this study develops a new prestressing system for NSM using CFRP tendons. The field-applicability of the developed prestressing system is evaluated through an application on a full-scale PC girder of 20 m with the objective of improving the girder’s performance by 30%. The girder is strengthened using 5 NSM CFRP tendons with the introduction of a prestressing force of 100 kN in each of them. The test results demonstrated the applicability of the new prestressing system since the flexural capacity of the girder was successfully increased by 30%.

Strengthening of concrete members with external fiber-reinforced polymer (FRP) has become a common practice to in the consulting engineering industry. The deflection of reinforced concrete beams strengthened with FRP is well studied. Conversely, limited studies are available to address the deflection analysis of prestressed reinforced concrete (PRC) beams strengthened with FRP. Nonlinear sectional analysis, simplified by implementing a trilinear moment-curvature response, is used in this paper to obtain closed form analytical deflection expressions for simply supported girders subjected to different loading conditions. The complete load-deflection response of PRC and PRC-FRP beams studied in this paper are generated using the presented procedure and compared to their testing results. To establish the accuracy of the trilinear approach, the analytically assumed moment-curvature predictions were compared to the test results performed by Larson, Peterman, and Rasheed (2005) on T-girders. To verify this response, a fully nonlinear analysis of the same T-girders strengthened with CFRP are performed. A comparison between the analytical and numerical moment-curvature responses are made and presented. The comparison indicates the high accuracy of the analytically assumed moment-curvature function, which represents the foundation for establishing the short-term deflection expressions. The proposed method produced accurate predictions for moment-curvature and short term load-deflection responses of PRC flexural members with straight strands and a T-cross section strengthened with externally bonded FRP. As such, this method shows high promise for establishing short-term deflection expressions that can be universally used in a variety of applications.

The aim of this project is to develop the necessary design knowledge to implement GFRP reinforcement in concrete traffic barriers. Innovation lies in the use of GFRP closed continuous stirrups that became recently available. The design method relies on AASHTO-LRFD Bridge Design Specification and the latest development in specifications issued by the Florida Department of Transportation (FDOT) for Reinforced Concrete (RC) Traffic Barriers. After a review of design procedures for traffic barriers and understanding the mechanical characteristics of GFRP reinforcement, a modified design approach is proposed to reduce GFRP reinforcement amounts and complexity in construction. Supported on experience gained from designing FDOT 32” F–Shape (F32) GFRP RC used in the Halls River Bridge Replacement Project, this study also addressed the 36”–Single Slope (SS36) traffic barrier to be adopted by FDOT in coming years.

In order to ensure a continuous and reliable path for the lateral loads caused by earthquake or wind forces, FRP-strengthened masonry walls that are part of the lateral load resisting system of a building require the joint work of the FRP strengthening to resist tensile stresses in the masonry and anchorage to the boundary structural elements (foundations or beams) to transfer the loads. This article presents the results of an investigation on the assessment of anchorage methods and FRP strengthening configurations for unreinforced masonry (URM) walls subjected to in-plane loads. Fourteen masonry walls were constructed for this experimental program. All of the walls were built with hollow clay bricks, typical of URM structures in Colombia and other parts of the world. The specimens for this investigation included slender and squat walls. The dimensions of the slender walls were 1.20 m. [4 ft] long, 1.90 m. [6.2 ft.] high, and 120 mm [4.8 in.] thick. The dimensions of the squat walls: 2.50 m. [8.2 ft.] long, 1.90 m. [6.2 ft.] high, and 120 mm [4.8 in.] thick. The walls were strengthened using two configurations: (1) Layout ‘H’ involving horizontal CFRP laminates along on wall side, and vertical CFRP laminates at each wall toe on one side of the wall, and (20 Layout ‘X’ involving diagonal CFRP laminates oriented at approximately 45 degrees on one side of the wall. Four anchor systems were evaluated: (1) System 1 (CFRP anchors embedded in the base beam), (2) System 2 (CFRP bonded to the base beam), (3) System 3 (FRP bonded to grout blocks), and (4) System 4 (FRP wrapped around grout blocks). The walls were tested in two series: (1) Series 1 – Monotonic Loading, and (2) Series 2 – Cyclic Loading. The test results demonstrated that Anchor System 4 was the most effective anchorage system. The walls strengthened with Anchor System 4 failed due to rupture of the CFRP laminates wrapped around the grout block. In general, the largest increases in in-plane capacity, when compared to the control walls, were observed in the slender walls. The walls with the ‘H’ Layout showed more ductility and less degradation of the lateral stiffness than the walls strengthened with the ‘X’ Layout.