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.

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.

Standard constitutive modeling of fiber-reinforced polymer composite laminates is typically based on uniaxial properties. The nonlinear in-plane shear behavior, of angle-ply laminates, is recognized long ago. This paper presents a model using test data generated from (±55o)ns symmetric angle-ply coupons to determine material response using an inverse mechanics approach. Nonlinear classical lamination theory is used to assemble the ply constitutive properties for global axial tensile response in terms of the secant shear modulus G12s values. The main objective of this study is to obtain the nonlinear in-plane shear stress-strain curves along the principal fiber-matrix direction. The resulting full-range material model is used to predict the response of (±55o)4s angle-ply FRP tubes used for stay in place form members manufactured by the filament winding process. The resulting analysis procedure accurately predicts the ultimate moment of the concrete filled tube and traces the deformation response reasonably well. In addition, the load-deflection analysis of the entire tube is performed and found to match well the experimental curve up to the limits of nonlinear material analysis when the large deformation of the tube is ignored.

A rapid repair or replacement method is developed for severely damaged concrete bridge columns due to cyclic loading. A carbon fiber-reinforced polymer (CFRP) shell and headed steel bars are used to relocate the column plastic hinge. The technique employs a steel collar with steel studs to increase bond of the original column to repair concrete inside the CFRP shell. Two bridge columns were damaged including concrete crushing and longitudinal steel bar pullout under quasi-static cyclic loads. One of the specimens required additional epoxy injection of the cracks; for the other specimen, the column and cap beam were decoupled before repair to simulate replacement of a column which sustained unrepairable damage. The technique successfully relocated the plastic hinge and restored strength and displacement capacity. Failure of the repaired specimens included concrete crushing and bar fracture. The technique is an accelerated bridge construction method and could be used to repair columns with repairable damage or replace columns with unrepairable damage.