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.

Flexural strengthening of reinforced concrete (RC) beams with fiber reinforced polymer (FRP) composites and two different bonding agents were investigated in this research. The bonding agents used in this research consisted of an epoxy paste and a sprayed polyurea. When polyurea was used as the bonding agent, it was sprayed to specific regions on the RC beams. Three RC beams were flexural strengthened with FRP composites according to the following techniques: (a) sprayed polyurea with and without glass FRP (GFRP) grid reinforcement, and (b) manual layup using one GFRP grid. Experimental results clearly indicate that flexural strengthening with the un-reinforced or reinforced polyurea technique is an effective strengthening scheme. Advantages of using polyurea over other epoxy based methods are that the application process requires significantly less time and the polyurea cures within minutes. Furthermore, no debonding of the un-reinforced or reinforced polyurea system was observed, suggesting a further benefit of this technique. Application of the polyurea system and key experimental results are presented and discussed herein.

This paper investigates experimentally the effect of sand coating bond enhancer on the flexural behavior of circular concrete-filled FRP tube (CFFT) by testing two full-scale CFFT cantilevers under lateral cyclic load. The full-bond between concrete and any kind of reinforcement is one of the main factors affecting on its flexural behavior. Limited research has investigated the bond effect on CFFT flexural behavior. The bond between the concrete core and the interior surface of the FRP tube is the main parameter of this study. Embedded-concrete strain gauges were used to measure the strain values inside the concrete core, then compared with the strain values measured from the electric strain gauges installed on the tube outer surface. The observed experimental results illustrate that the sand coating increases the flexural strength and stiffness of circular CFFT members. No slippage was observed on the sand-coated specimen; while 6 mm (0.24 in) slippage was measured on the specimen without sand coating. The internal and external strain curves are identical for the sand-coated specimen; while these curves are incompatible for the specimen without sand coating. The experimental results demonstrate the significance of investigating the bond effect and the sand coating contribution to improve the bond between the concrete core and the FRP tube, and assure a good composite action under flexural loads.

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.