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.

Fiber reinforced polymer (FRP) has been extensively used in civil infrastructure in recent decades. The uncertainty of its unidirectional tensile strength is of great importance for analysis and design with respect to structural safety. In this work, a large database comprising 40 data sets of carbon- and glass-fiber reinforced polymer tensile tests is fitted by the Normal, Lognormal and Weibull distributions. The observed significance level (OSL) which is based on the Anderson-Darling statistic is used for determining the goodness-of-fit. Fitting results show that all three distributions can be used for the tensile strength of FRP composites from the perspective of experimental justification. However, the Weibull distribution is preferred as it reveals the weakest link hypothesis of failure and is the most commonly used distribution for composites.

This paper investigates the behavior of short concrete columns strengthened with externally bonded longitudinal carbon fiber-reinforced polymer (CFRP) laminates combined with transverse basalt fiber-reinforced polymer (BFRP) wraps. A total of eighteen 500 mm-long [19.69 in-long] concrete column specimens with a square cross section (150 mm [5.91 in] width) were tested with different longitudinal and transverse reinforcement combinations under concentric and eccentric axial loadings. For eccentric loading, three end eccentricity to width ratios of 0.1, 0.2, and 0.3 were applied symmetrically at both ends of each simply supported column specimen to provide single curvature condition. The compressive longitudinal CFRP strips, in average, experienced 38% of their tensile rupture strain. The experimental results showed debonding of longitudinal CFRP laminates from concrete surface and buckling of bonded specimens as the dominant mode of failure, and revealed that transverse wrapping system is efficient in postponing the buckling/debonding failure.

The bond between external bonding (EB) of fiber reinforced polymer (FRP) composite materials to concrete is the weakest link in the strengthened concrete flexural members. There are three mechanisms to transfer the interfacial shear between FRP and the concrete substrate, i.e., adhesion, interlocking and friction. This paper proposes a new approach by grooving on the concrete surface before applying epoxy to make epoxy ribs to increase interlocking. An experimental program was conducted to verify the effectiveness of the proposed epoxy ribs. Six grooves perpendicular to the fiber direction were cut on the bonding surface of the concrete blocks. The grooves were filled by wax in the unfilled specimens and with epoxy primer in the epoxy filled specimens before CFRP plate was installed. The experimental results show that epoxy-filled grooves can significantly improve the bond between FRP and concrete.

Anchorage devices can enhance the strength and deformability of reinforced concrete (RC) structures strengthened with fiber-reinforced polymer (FRP) materials. Anchorage can also result in a higher utilization of the desirable strength properties of the FRP. FRP anchors are commonly used in practice as such anchors are particularly well-suited to a wide range of structural forms and FRP applications. While there have been numerous experimental studies reported to date concerned with FRP anchors applied to FRP-strengthened RC structures, the limited amount of associated design rule development has inhibited the rational design and practical application of anchors. An overview of selected FRP anchor design models that have been reported in the literature is presented herein, as well as a commentary on the applicability and limitations of the models. A potential anchor design methodology is developed to illustrate how the different models can be combined towards the rational design of such anchors in FRP strengthening systems. Design examples are also included to demonstrate the enhancement of strength due to anchors and the design of the anchors in common strengthening applications currently available in ACI 440.2R (2008). Finally, shortcomings in the current state of knowledge and topics meriting further research are discussed.