scholarly journals Bond-Slip Models for FPR-Concrete Interfaces Subjected to Moisture Conditions

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Justin Shrestha ◽  
Dawei Zhang ◽  
Tamon Ueda
Keyword(s):  
Fiber Reinforced Polymers ◽  
Experimental Investigations ◽  
Reinforced Polymers ◽  
Bond Slip ◽  
Exposure Effect ◽  
Pull Out ◽  
Proposed Model ◽  
Maximum Period ◽  
Moisture Conditions

Environmental related durability issues have been of great concerns in the structures strengthened with the fiber reinforced polymers (FRPs). In marine environment, moisture is one of the dominant factors that adversely affect the material properties and the bond interfaces. Several short-term and long-term laboratory experimental investigations have been conducted to study such behaviors but, still, there are insufficient constitutive bond models which could incorporate moisture exposure conditions. This paper proposed a very simple approach in determining the nonlinear bond-slip models for the FRP-concrete interface considering the effect of moisture conditions. The proposed models are based on the strain results of the experimental investigation conducted by the authors using 6 different commercial FRP systems exposed to the moisture conditions for the maximum period of 18 months. The exposure effect in the moisture conditions seems to have great dependency on the FRP system. Based on the contrasting differences in the results under moisture conditions, separate bond-slip models have been proposed for the wet-layup FRP and prefabricated FRP systems. As for the verification of the proposed model under moisture conditions, predicted pull-out load was compared with the experimental pull-out load. The results showed good agreement for all the FRP systems under investigation.

scholarly journals EMPIRICAL SHEAR BASED MODEL FOR PREDICTING PLATE END DEBONDING IN FRP STRENGTHENED RC BEAMS

2021 ◽  
Vol 27 (2) ◽  
pp. 117-138
Author(s):  
Ahmed K. El-Sayed ◽  
Mohammed A. Al-Saawani ◽  
Abdulaziz I. Al-Negheimish
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Failure Mode ◽  
Fiber Reinforced Polymers ◽  
Simplified Model ◽  
Rc Beams ◽  
Shear Cracks ◽  
Reinforced Polymers ◽  
Experimental Database ◽  
Proposed Model

This paper presents the development of a simplified model for predicting plate end (PE) debonding capacity of reinforced concrete (RC) beams flexurally strengthened using fiber reinforced polymers (FRP). The proposed model is based on the concrete shear strength of the beams considering main parameters known to affect the opening of the shear cracks and consequently affect PE debonding. The model considers also the effect of the location of the cut-off point of FRP plate along the span of the beam. The proposed model was verified against experimental database of 128 FRP-strengthened beams collected from previous studies that failed in PE debonding. In addition, the predictions of the proposed model were also compared with those of the existing PE debonding models. The predictions of the model were found to be comparable to the best predictions provided by the existing models, yet the proposed model is simpler. Furthermore, the proposed model was combined with the ACI 440 IC debonding equation to provide a procedure for predicting the governing debonding failure mode in FRP strengthened RC beams. The procedure was validated against 238 beam tests available in the literature, and shown to be a reliable approach.

Bond Behavior of CFRP Cured Laminates: Experimental and Numerical Investigation

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
M. Naser ◽  
R. Hawileh ◽  
J. A. Abdalla ◽  
A. Al-Tamimi
Keyword(s):  
Reinforced Concrete ◽  
Fe Simulation ◽  
Experimental Studies ◽  
Theoretical Work ◽  
Experimental Results ◽  
Fiber Reinforced Polymers ◽  
Experimental Investigations ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
Bond Behavior

The use of externally bonded carbon fiber-reinforced polymers (CFRPs) as strengthening systems to improve the condition and overall capacity of existing reinforced concrete structural members is found to be a promising scheme. This field has drawn the attention of many researchers in the past two decades through the implementation of much theoretical work as well as experimental studies. It was evident through many experimental investigations conducted by a number of researchers that the bond action between fiber-reinforced polymers and reinforced concrete members is considered one of the main factors affecting the performance and reliability of external strengthening systems and warrants further investigation. Debonding failure is a brittle mode of failure that may occur prematurely before strengthened members develop their full composite and expected capacities. This paper aims to investigate the bond behavior between the CFRP-concrete interface via experimental work and finite element (FE) simulations. The experimental study consisted in testing nine concrete prisms with different bonded lengths of the CFRP plates that vary between 25% (60 mm), 50% (120 mm), and 75% (180 mm) of the total length of the concrete prisms and instrumented with strain gauges. A FE simulation model was created and validated using the experimental results of the tested specimens, and a parametric study was carried out to investigate the effect of several parameters on the bond behavior between CFRP and concrete surfaces. The trend of the FE simulation results shows a good agreement with the experimental results and those available in the literature. It was observed that the optimum length of the CFRP plate is in the range between 150 mm and 160 mm when bonded to concrete surfaces. Other conclusions and observations were drawn based on the experimental and numerical results.

scholarly journals Eddy current modeling in linear and nonlinear multifilamentary composite materials

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 183-187 ◽  
Author(s):  
Hocine Menana ◽  
Mohamad Farhat ◽  
Melika Hinaje ◽  
Kevin Berger ◽  
Bruno Douine ◽  
...  
Keyword(s):  
Composite Materials ◽  
Frequency Domain ◽  
Eddy Currents ◽  
Ac Loss ◽  
Fiber Reinforced Polymers ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Differential Formulation ◽  
High Anisotropy ◽  
Proposed Model

Abstract In this work, a numerical model is developed for a rapid computation of eddy currents in composite materials, adaptable for both carbon fiber reinforced polymers (CFRPs) for NDT applications and multifilamentary high temperature superconductive (HTS) tapes for AC loss evaluation. The proposed model is based on an integro-differential formulation in terms of the electric vector potential in the frequency domain. The high anisotropy and the nonlinearity of the considered materials are easily handled in the frequency domain.

Bond Behaviour between GFRP Reinforcement and Concrete Using a Pull-Out Test

2018 ◽  
Vol 272 ◽  
pp. 232-237
Author(s):  
Natalia Gažovičová ◽  
Juraj Bilčík ◽  
Ivan Hollý ◽  
Jaroslav Halvonik
Keyword(s):  
Test Methods ◽  
Steel Reinforcement ◽  
Fiber Reinforced Polymers ◽  
Mechanical Interlocking ◽  
Bond Behaviour ◽  
Reinforced Polymers ◽  
Rc Structures ◽  
Pull Out ◽  
Corrosion Of Steel ◽  
Gfrp Reinforcement

Corrosion of steel reinforcement is one of the most often deterioration reasons of RC structures. At present, the corrosion of steel reinforcement can be avoided by using non-metallic reinforcement from composite materials, especially in structures that are exposed to extreme environmental environment. These materials are durable and non-conductive. They are composited from two materials: fibres and matrix. The most commonly used FRP (Fiber Reinforced Polymers - FRP) reinforcement are glass fibre reinforced polymers (GFRP). The bar surface can be e.g. sanded, wrapped, with helically wound ribs. The bond between concrete and reinforcement is one of the basic requirements for the composite action of both materials. The transfer of forces between the steel reinforcement and the concrete is provided by the following mechanisms: adhesion, friction and mechanical interlocking. The bond between GFRP reinforcement and concrete is different and it is ensured by friction and mechanical interlocking of the rebar surface. The chemical bond does not originate between GFRP reinforcement and the surrounding concrete, so adhesion does not contribute to transfer of the bond forces. Some few test methods are used to determine the bond between GFRP reinforcement and concrete. The pull-out test were used to determine the bond behaviour between GFRP rebars and concrete. This paper describes the preparation, process, results and evaluation of the pull-out tests.

scholarly journals The Bond-Slip Relationship at FRP-to-Brick Interfaces under Dynamic Loading

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 545
Author(s):  
Di Zhang ◽  
Jun Yang ◽  
Li Yuan Chi
Keyword(s):  
Dynamic Loading ◽  
Slip Rate ◽  
Fiber Reinforced Polymers ◽  
Interface Debonding ◽  
Strain Rate Effects ◽  
Slip Rates ◽  
Reinforced Polymers ◽  
Bond Slip ◽  
Lap Shear ◽  
Dynamic Enhancement

Interface debonding between fiber reinforced polymers (FPR) and substrates is the principal failure mode for FRP-reinforced structure. To understand the bond–slip relationship at FRP-to-brick interfaces under dynamic loading, the influences of the dynamic enhancement of material performance on the bond–slip curve were studied. Single-lap shear tests under two different loading rates were performed, and the slip distribution curves at different loading stages were fitted to derive the bond–slip relationship. Then a numerical model considering the strain rate effects on materials was built and verified with test results. Further, the influences of brick strength, FRP stiffness and slip rate on the bond–slip relationship were investigated numerically. The research results show that FRP stiffness mainly influences the shape of the bond–slip curve, while brick strength mainly influences the amplitude of the bond–slip curve. The variations of the bond–slip relationship under dynamic loading, i.e., under different slip rates, are mainly caused by the dynamic enhancement of brick strength, and also by the dynamic enhancement of FRP stiffness, especially within a specific slip rate range. The proposed empirical formula considering dynamic FRP stiffness and dynamic brick strength can be used to predict the bond–slip relationship at the FRP-to-brick interface under dynamic loading.

scholarly journals Hygrothermal Aging of Amine Epoxy: Reversible Static and Fatigue Properties

2018 ◽  
Vol 8 (1) ◽  
pp. 447-454 ◽  
Author(s):  
Andrey E. Krauklis ◽  
Abedin I. Gagani ◽  
Andreas T. Echtermeyer
Keyword(s):  
Fiber Reinforced Polymers ◽  
Fatigue Properties ◽  
Initial Water Content ◽  
Initial Water ◽  
Reinforced Polymers ◽  
Structural Applications ◽  
High Concern ◽  
Static Tensile ◽  
Aging Mechanisms

Abstract Fiber-reinforced polymers (FRP) are widely used in structural applications. Long-term properties of such materials exposed to water are of high concern and interest, especially for subsea and offshore applications. The objective of this study is to identify the mechanisms and to identify whether drop in properties of diamine-cured mixed DGEBA-HDDGE is reversible upon drying the material to its initial water content. The properties of interest are mechanical strength, elastic properties and fatigue performance, as well as changes in chemical structure. The effect of absorbed water on the properties of the resin is evaluated, and hygrothermal effects and aging mechanisms are discussed. Furthermore, it is shown experimentally that the tension fatigue S-N curve of a wet epoxy resin can be estimated by shifting the S-N curve of a dry material proportionally to a reduction in static tensile strength due to hygrothermal effects.

scholarly journals Durability of FRP Reinforcements and Long-Term Properties

2020 ◽  
Vol 28 (2) ◽  
pp. 50-55 ◽  
Author(s):  
Katarína Gajdošová ◽  
Róbert Sonnenschein ◽  
Stanislav Blaho ◽  
Simona Kinčeková ◽  
Ján Pecka
Keyword(s):  
Experimental Studies ◽  
Fiber Reinforced Polymers ◽  
Actual Behavior ◽  
Design Codes ◽  
Reinforced Polymers ◽  
Frp Composites ◽  
Impact Reduction ◽  
Long Term Behavior ◽  
Insufficient Knowledge

AbstractAlthough fiber-reinforced polymers (FRPs) have achieved increasing popularity in strengthening concrete structures and reinforcing new ones, there is to date insufficient knowledge about their long-term behavior. The long-term properties of FRPs specified in design codes lead to the low utilization capacity of these materials and are not supposed to be correct according to the actual behavior of structures reinforced with FRPs after 20 or 30 years of their use. Environmental impact reduction factors limit the mechanical properties of FRP composites in a range from 0.95 for CFRP to 0.5 for GFRP; the creep rupture factor is from 0.9 to 0.2. The paper summarizes previous research and experimental studies on the long-term properties of FRP reinforcements and also their comparison with the actual structures in which this reinforcement has been used; it presents the first part of an experimental investigation with comparative calculations.

scholarly journals Thermal and Fire Characteristics of FRP Composites for Architectural Applications

2021 ◽  
Author(s):  
Umberto Berardi ◽  
Nicholas Dembsey
Keyword(s):  
Cost Effective ◽  
Fiber Reinforced Polymers ◽  
Design Practice ◽  
Reinforced Polymers ◽  
Frp Composites ◽  
Design Fire ◽  
Current Design ◽  
Fire Loads ◽  
Fire Characteristics

This paper discusses the main challenges of using fiber reinforced polymers (FRPs) in architectural applications. Architects are showing increased interest in the use of FRPs in modern buildings thanks to FRPs’ ability to allow cost effective realization of unique shapes and flexible aesthetics, while accommodating architectural designs and needs. The long-term durability, weathering resistance, and the exceptional mechanical properties have recently suggested the adoption of FRPs for building façade systems in an increasing number of buildings worldwide. However, some challenges for a wider adoption of FRPs in buildings are represented by the environmental and thermal aspects of their production, as well as their resistance to the expected “fire loads”. This last aspect often raises many concerns, which often require expensive fire tests. In this paper, the results of cone calorimeter tests are compared with software simulations to evaluate the possibility of designing FRPs on the computer as opposed to current design practice that involves iterative use of fire testing. The comparison shows that pyrolysis simulations related to FRPs are still not an effective way to design fire safe FRPs for architectural applications.

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