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.

Utilization of fiber-reinforced polymers (FRPs) in concrete structures, particularly bridges, has promised a safe and satisfactory performance. However, the structural performance of FRP-reinforced bridges can be affected by occurrence of various types of damage. This paper presents structural damage identification in FRP-reinforced bridge truss girders tested under static and fatigue loading. The proposed technique combines discrete wavelet transforms (DWTs) and spectral entropy in a relative procedure to detect and quantify the damage-induced disturbances in the measured vibrational signals of the girders. Various types of test-induced damage were identified using the vibrational signals obtained only from the damaged state of the girders. Results of damage identification were verified by data obtained through instrumentations and by visual inspection of the actual state of damage in the girders during and after the tests. The results show that the technique can be implemented in a protective structural health monitoring (SHM) system to identify imminent failure. It can also help with the decision-making process regarding maintenance of FRP-reinforced concrete bridges. The technique is a practical means for damage identification in in-situ cases, where the normal operation of bridges cannot be interrupted, and the data obtained from a reference state of bridges are not available.

The elastic nature of fiber-reinforced polymer (FRP) reinforcement raises concerns about the feasibility of using this type of reinforcement in reinforced concrete (RC) structures in seismic regions. To date, no studies have been conducted to investigate the seismic response of GFRP-RC slab-column connections. This paper presents the results of an experimental program carried out to assess the lateral displacement deformability of slab-column edge connections reinforced with GFRP reinforcement. Two full-scale connections were tested under gravity and reversed-cyclic lateral loading. One connection was reinforced with steel reinforcement, while the other one was reinforced with the same reinforcement ratio of GFRP reinforcement. The GFRP-RC connection was able to sustain a 2.5% drift ratio, which is higher than the 1.5% minimum drift ratio for the steel-RC counterpart. This indicates the ability of GFRP-RC edge connections to undergo or exceed the suggested seismic drifts while maintaining their gravity load carrying capacity.