scholarly journals Experimental Study on FRP-to-Concrete Bonded Joints with FRP Sheet Anchor System

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Weiwen Li ◽  
Wei Liu ◽  
Xu Yang ◽  
Feng Xing
Keyword(s):  
Design Guidelines ◽  
Reinforced Concrete Beams ◽  
Constitutive Relationship ◽  
Bond Slip ◽  
Anchor System ◽  
Concrete Members ◽  
Cfrp Sheet ◽  
Externally Bonded ◽  
Anchor Systems ◽  
Frp Sheet

Fiber-reinforced polymer (FRP) has been widely used for retrofitting and strengthening concrete structures over the past two decades. Because concrete members retrofitted by externally bonded FRP sheets can fail prematurely in debonding because of the fracture between FRP and concrete, FRP tensile strength cannot be fully utilized in engineering practices. Numerous useful investigations have been conducted to develop effective anchor systems to restrict FRP debonding. Thus, an FRP sheet-anchor system was developed and observed to be one of the most effective and convenient anchor systems. The FRP sheet-anchor system is applied to reinforced concrete beams strengthened with U-wrapping and side-bonded FRP configurations in few design guidelines. However, only a few investigations have focused on the failure mechanism of the FRP sheet-anchor system in the existing literature. Therefore, the main objective of this study is analyzing the effect of the carbon FRP (CFRP) sheet-anchor system on the bonding behavior of the CFRP-concrete interface, particularly the effect of the width and stiffness of the CFRP sheet-anchor system. In addition, the anchor-strengthened stage is defined by the load-slip response, which is different from that of specimens without the CFRP sheet-anchor system. Based on the experimental results, three linear stage models of the bond-slip constitutive relationship are proposed in this study.

Numerical Tracking of the Behavior of Repaired Reinforced Concrete Beams by CFRP Sheets against Shear

2020 ◽  
Vol 1002 ◽  
pp. 604-614
Author(s):  
Hayder Hussein H. Kammona ◽  
Muhammad Abed Attiya ◽  
Qasim M. Shakir
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Cfrp Sheets ◽  
Shear Span ◽  
Concrete Members ◽  
Suggested Technique ◽  
Cfrp Sheet ◽  
Failure Loads

This study simulates a procedure of rehabilitation of reinforced concrete beams with the aid of ANSYS 17 software. In this work, the BIRTH and DEATH procedure (in ANSYS) was adopted to model the post-repairing stage. This aspect has rarely been considered by previous studies that utilized a carbon fiber reinforced polymer (CFRP) sheet when retrofitting. To verify the suggested technique, six specimens were analyzed with two values of shear span-to-depth ratios (3 and 4) and three spaces of CFRP sheets (100mm, 150mm and 200mm). The effect of the repairing process on the structural performance of the retrofitted beam is also investigated.It is found that the suggested technique yielded a good agreement with the experimental results and the maximum differences in the failure loads between the numerical and experimental results were 10% and 4% for shear span-to-depth ratios of 3 and 4, respectively. It was also ascertained that upgrading reinforced concrete members within the early stages of loading showed a better enhancement in the loading capacity compared to upgrading reinforced concrete members close to the juncture of failure.

A proposed strengthening model considering interaction of concrete-stirrup-FRP system for RC beams shear-strengthened with EB-FRP sheets

2018 ◽  
Vol 37 (10) ◽  
pp. 685-700 ◽  
Author(s):  
Weiwen Li ◽  
Chengyue Hu ◽  
Zejie Pan ◽  
Wei Peng ◽  
Yong Yang ◽  
...  
Keyword(s):  
Effective Strain ◽  
Polymer System ◽  
Design Guidelines ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites ◽  
Externally Bonded

Many factors can affect the shear capacity of fiber-reinforced polymer in reinforced concrete beams shear-strengthened with externally bonded fiber-reinforced polymer composites. Undoubtedly, the interaction of concrete-stirrup-fiber-reinforced polymer system is one of the key factors. However, most of the existing fiber-reinforced polymer design guidelines do not take account of this important factor on predicting fiber-reinforced polymer shear capacity. This study provides an advanced strengthening model that comprehensively considers the interaction among concrete, stirrup, and fiber-reinforced polymer for calculating the fiber-reinforced polymer effective strain. The advanced strengthening model provides a more accurate prediction for the fiber-reinforced polymer shear contribution compared with existing design guidelines.

Test Analysis for RC Beams Strengthened with Externally Bonded Prestressed CFRP Laminates

2008 ◽  
Vol 385-387 ◽  
pp. 41-44 ◽  
Author(s):  
Shi Qi Cui ◽  
Jin Shan Wang ◽  
Zhao Zhen Pei ◽  
Zhi Liu
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Test Results ◽  
Test Analysis ◽  
Cfrp Laminates ◽  
Cfrp Sheet ◽  
Externally Bonded

Reinforced concrete beams strengthened with externally bonded CFRP sheet and prestressed CFRP are analyzed in this paper. Crack developments and displacements with curvatures for different beams are analyzed. Test results show that prestressed CFRP are able to control the development of macro cracks in concrete and prestressed CFRP is an effective method to improve the toughness of concrete, reduce strengthening cost and meanwhile enhance bearing capacity of concrete beams.

scholarly journals EFFICIENCY OF FLEXURAL STRENGTHENING OF REINFORCED CONCRETE BEAMS BY NEAR SURFACE MOUNTED CARBON FIBER REINFORCEMENT POLYMER RODS AND EXTERNALLY BONDED SHEETS

2021 ◽  
Vol 25 (Special) ◽  
pp. 4-100-4-114
Author(s):  
Wissam S. Abdullah ◽  
◽  
Hassan F. Hassan ◽  
Keyword(s):  
Load Capacity ◽  
Reference Beam ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Ultimate Load Capacity ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Cfrp Sheet ◽  
Externally Bonded ◽  
Near Surface Mounted

This study investigated the flexural behavior of reinforcement concrete beam strengthened with different techniques. The purpose of this research to study the various techniques of strengthening and knowing the effect of each technique on the beam behavior .Ten simply supported beams tested in this study. The total length of the beams and clear span were 1800mm and 1650mm, respectively. The cross section was (180×250) mm. Tested beams were divided into two categories’ the first category consist of one beams and considered as reference, while the second category consist of nine beams divided into Two groups according to the Strengthening techniques such as near surface mounted (NSM) and external bonded reinforcement (EBR).The experimental results showed improvement in ultimate load capacity for strengthened beams ranging from (6 to 89%) for NSM and (31 to 96%) for EBR and reduction in deflection for strengthened beams ranging from (6 to 43%) as compared with reference beam. When the number and length of CFRP bars are increased, the number of cracks increase while the width of the cracks and the spacing decrease, and the same observation is made when the width of the CFRP sheet is increased. The experimental load capacities of strengthened beams were compared with the design provisions given by ACI440.2R-17 guideline for NSM and EBR technique and EC2 guideline for EBR technique, the average ratio (1.2 and 0.97) respectively ,which showed that reasonable and a good agreement for all strengthened beams.

scholarly journals Application of Sustainable Bamboo-Based Composite Reinforcement in Structural-Concrete Beams: Design and Evaluation

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 696 ◽  
Author(s):  
Alireza Javadian ◽  
Ian F. C. Smith ◽  
Dirk E. Hebel
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Design Guidelines ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Structural Concrete ◽  
Concrete Members ◽  
Reinforced Polymer ◽  
Composite Reinforcement

Reinforced concrete is the most widely used building material in history. However, alternative natural and synthetic materials are being investigated for reinforcing concrete structures, given the limited availability of steel in developing countries, the rising costs of steel as the main reinforcement material, the amount of energy required by the production of steel, and the sensitivity of steel to corrosion. This paper reports on a unique use of bamboo as a sustainable alternative to synthetic fibers for production of bamboo fiber-reinforced polymer composite as reinforcement for structural-concrete beams. The aim of this study is to evaluate the feasibility of using this novel bamboo composite reinforcement system for reinforced structural-concrete beams. The bond strength with concrete matrix, as well as durability properties, including the water absorption and alkali resistance of the bamboo composite reinforcement, are also investigated in this study. The results of this study indicate that bamboo composite reinforced concrete beams show comparable ultimate loads with regards to fiber reinforced polymer (FRP) reinforced concrete beams according to the ACI standard. Furthermore, the results demonstrate the potential of the newly developed bamboo composite material for use as a new type of element for non-deflection-critical applications of reinforced structural-concrete members. The design guidelines that are stated in ACI 440.1R-15 for fiber reinforced polymer (FRP) reinforcement bars are also compared with the experimental results that were obtained in this study. The American Concrete Institute (ACI) design guidelines are suitable for non-deflection-critical design and construction of bamboo-composite reinforced-concrete members. This study demonstrates that there is significant potential for practical implementation of the bamboo-composite reinforcement described in this paper. The results of this study can be utilized for construction of low-cost and low-rise housing units where the need for ductility is low and where secondary-element failure provides adequate warning of collapse.

Flexural Behaviour of RC Beams Strengthened with Prestressed CFRP Plates：Comparisons of Bonded and Unbonded Method

2011 ◽  
Vol 480-481 ◽  
pp. 283-287
Author(s):  
Lang Ni Deng ◽  
Peng Zhang ◽  
Hua Chen
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Reinforced Concrete Beams ◽  
Flexural Behaviour ◽  
Bending Tests ◽  
Flexural Performance ◽  
Concrete Members ◽  
Four Point Bending ◽  
Anchorage System ◽  
Externally Bonded

In this study, a total of 5 CFRP-strengthened reinforced concrete beams were tested in flexure based on the independent development prestressing anchorage system. The various variables included bonding or no bonding of the CFRP and the amount of prestressing. The experiments consisted of one control beam, two prestressed CFRP-unbonded beams, and two prestressed CFRP-bonded beams, all the beams were subjected to four-point bending tests. The ultimate load, deformation, and CFRP strain were examined. The aim of this investigation was to study the flexural performance of reinforced concrete members strengthened using CFRP plates, employing different CFRP bonding and prestressing methods. The failure mode of the prestressed CFRP-plated beams was not debonding, but concrete crushing or FRP rupture. For the reinforced concrete members strengthened with externally bonded prestressed CFRP plates, after the debonding of the CFRP plates that occurred in the bonded cases, the behaviour of the bonded CFRP-plated beams changed to that of the unbonded CFRP-plated beams due to the effect of the anchorage system. The ductility indices of the beams in an unbonded system were less than that of those in a bonded system.

scholarly journals Evaluating Flexural Strength of RC Beams Strengthened by CFRP using Different Analytical Models

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Riyam J. Abed ◽  
Mohammed A. Mashrei ◽  
Ali A. Sultan
Keyword(s):  
Flexural Strength ◽  
Prediction Models ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Analytical Models ◽  
Rc Beams ◽  
Test Results ◽  
Related Field ◽  
Cfrp Sheet ◽  
Externally Bonded

Abstract This paper deals with reinforced concrete beams strengthened by CFRP in flexure. The debonding between CFRP and the surface of the beam is the main problem. Many researchers around the world have made extensive efforts to study the phenomenon of debonding for efficient applications. Based on these efforts and different related field applications, code previsions and various models have been proposed for predicting debonding failure. Two code previsions and three typical models are presented in the current study. ACI-440.2R 17, CNR-DT 200 R1/2013, Said and Wu, Lu et al., and Teng et al. have been used to estimate the flexural strength of RC beams strengthened by CFRP with and without grooves. Test results of eleven flexural beams strengthened by CFRP sheet/laminate using externally bonded reinforcement (EBR) and externally bonded reinforcement on grooves (EBROG) methods were used in the current paper. The performance and accuracy of each model were evaluated based on these test results. Most of the prediction models that used in this study give a closer prediction of the flexural strength of beams strengthened by EBR compared to that of the beams strengthened by EBROG. Finally, the prediction results of CNR-DT 200 R1/2013 were the most accurate and approval with test results compared with other models in the current study

scholarly journals Glass transition effect of adhesive in timber beams strengthened with CFRP overlays

2019 ◽  
Vol 262 ◽  
pp. 03001
Author(s):  
Rafał Krzywon ◽  
Janusz Brol
Keyword(s):  
Mechanical Performance ◽  
Adhesive Layer ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Reinforced Composite ◽  
The Press ◽  
Cfrp Sheet ◽  
Externally Bonded ◽  
Temperature Ranges ◽  
Timber Beams

There are situations when timber structure requires strengthening caused by environmental deterioration or changes in load conditions. Its mechanical performance can be increased by use of externally bonded high strength fibre reinforced composite (FRP). The place of application increases the sensitivity of this technique to environmental effects, including heating by the sun rays. Surface temperature can exceed 70 °C, while usually as safe is considered 45 °C. Paper describes the tests of timber beams strengthened with two types of composites: unidirectional CFRP sheet and CFRP strip. They were heated at various temperature ranges and tested in bending. Out of the nine tested beams, only one heated to 95 °C was not damaged by the delamination of the composite overlay, remaining beams have not been destroyed due to achieved deflection exceeding the press cylinder range or were failed due to rupture of carbon fibres. The influence of the temperature was better recognizable in differences of deflections and strains caused by the creep in the adhesive layer weakened by temperature. It should also be emphasized that got results are much better than for commonly tested reinforced concrete beams, where delamination caused failure slightly above 65 °C.

scholarly journals SERVICEABILITY ANALYSIS OF FLEXURAL REINFORCED CONCRETE MEMBERS / LENKIAMŲJŲ GELŽBETONINIŲ ELEMENTŲ TINKAMUMO ANALIZĖ

2012 ◽  
Vol 18 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Gintaris Kaklauskas ◽  
Viktor Gribniak ◽  
Ronaldas Jakubovskis ◽  
Eugenijus Gudonis ◽  
Donatas Salys ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Numerical Procedure ◽  
Reinforced Concrete Beams ◽  
Crack Model ◽  
Test Results ◽  
Rigid Plastic ◽  
Bond Slip ◽  
Concrete Members ◽  
Discrete Crack ◽  
Average Bond

The paper presents a simple discrete crack model for analyzing the deformation and crack width of reinforced concrete beams. The model is based on a non-iterative algorithm and uses a rigid-plastic bond-slip law and elastic properties of materials. Curvatures and crack widths predicted by the proposed technique were checked against the test results of six experimental beams, reported by the authors and other investigators. The article also proposes and discusses a numerical procedure for deriving the average bond stress with reference to the test data. Serviceability analysis resulted in a reasonable agreement on the test measurements. Santrauka Straipsnyje pateikiamas supaprastintas diskrečiųjų plyšiu modelis gelžbetoninių sijų deformacijų ir plyšio pločio analizei. Modelis pagrįstas neiteraciniu algoritmu, remiantis standžiai plastiniu sukibimo desniu ir tampriosiomis medžiagų savybėmis. Remiantis skirtingų autorių atliktais eksperimentiniais duomenimis, modelis patikrintas skaičiuojant gelžbetoninių sijų kreivius ir plyšio pločius. Apskaičiuotos kreivių ir plyšio pločių reikšmės gana tiksliai sutapo su eksperimentiniais rezultatais. Taip pat pasiūlytas originalus vidutinių sukibimo įtempių apskaičiavimo metodas, remiantis eksperimentiniais lenkiamujų gelžbetoninių sijų bandymo rezultatais.

Nonlinear Analysis for RC Beams Strengthened by Externally Bonded Steel Plates with Bond-Slip

2015 ◽  
Vol 723 ◽  
pp. 387-391
Author(s):  
T.B. Liu ◽  
Jian Chang Zhao ◽  
S.W. Liu
Keyword(s):  
Reinforced Concrete ◽  
Nonlinear Analysis ◽  
Tensile Force ◽  
Constitutive Law ◽  
Steel Plates ◽  
Constitutive Relationship ◽  
Rc Beams ◽  
Concentrated Load ◽  
Bond Slip ◽  
Externally Bonded

The RC beams strengthened by externally bonded steel plates are regarded as composite beams which consist of steel plates and reinforced concrete with bond-slip. Based on the deformation compatibility relationship between steel plates and reinforced concrete, the constitutive relationship which can reflect the mechanical properties of steel plates and reinforced concrete and the bond-slip constitutive law, a nonlinear differential equation for the beam, expressed in the form of the tensile force of steel plates, is derived. A nonlinear analytical solution under the double concentrated load of the RC beams strengthened by externally bonded steel plates is obtained. By which a coordination coefficient in the form of the characteristic value of the beam is deduced. By using the coordination coefficient, a practical nonlinear analysis method, which can exactly reflect the bearing capacity and deformation of the beam is established.

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