scholarly journals The Influence of CFRP Orientation Angle on the Shear Strength of RC Beams

2018 ◽  
Vol 12 (1) ◽  
pp. 269-281 ◽  
Author(s):  
Yasmin Murad
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Orientation Angle ◽  
Shear Behaviour ◽  
Experimental Program ◽  
Rc Beams ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Cfrp Sheet

Background:Carbon Fiber Reinforced Polymer (CFRP) sheets are widely used for strengthening and repairing reinforced concrete structures. Previous experimental studies have shown that strengthening Reinforced Concrete (RC) beams with CFRP sheet can be greatly influenced by the configuration, orientation and properties of the CFRP sheets.Objective:The behaviour of RC beams, strengthened with 60° and 45° inclined CFRP sheets, has not clearly explained.Method:Thus, an experimental program, proposed in this paper, investigates the shear behaviour of RC beams strengthened with CFRP sheets under different orientation angles including 0˚, 45˚, 60˚ and 90˚.Result:The study shows that strengthening RC beams with CFRP is highly influenced by the orientation angle of the sheets. The influence of CFRP sheets is remarkable on increasing the ultimate deflection, ductility and shear strength of RC beams.Conclusion:It is beneficial to strengthen RC beams, which are weak in shear, obliquely using 45˚ or 60˚ inclined CFRP sheets.

scholarly journals An experimental study on flexural strengthening of RC beams using CFRP sheets

2018 ◽  
Vol 7 (4) ◽  
pp. 2075 ◽  
Author(s):  
Yasmin Murad
Keyword(s):  
Flexural Strength ◽  
Orientation Angle ◽  
Longitudinal Axis ◽  
Flexural Behavior ◽  
Experimental Program ◽  
Rc Beams ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Cfrp Sheets ◽  
Reinforced Polymer

 The use of carbon fiber reinforced polymer (CFRP) sheets is becoming a widely accepted solution for strengthening and repairing rein-forced concrete (RC) structures. To date, the behavior of RC beams, strengthened with 60˚ and 45˚ inclined CFRP sheets, has not clearly explained. An experimental program is proposed in this paper to investigate the flexural behavior of RC beams strengthened with CFRP sheets. CFRP sheets were epoxy bonded to the tension face to enhance the flexural strength of beams inducing different orientation angles of 0˚, 45˚, 60˚ and 90˚ with the beam longitudinal axis. The study shows that strengthening RC beams with CFRP sheets is highly influenced by the orientation angle of the sheets. The orientation angle plays a key role in changing the crack pattern and hence the failure mode. The influence of CFRP sheets was adequate on increasing the flexural strength of RC beams but the ductility of the beams was reduced. The best performance was obtained when strengthening RC beam obliquely using 45˚ inclined CFRP sheets where the specimen experienced additional deflection and strength of 56% and 12% respectively and the reduction in its ductility was the least. It is recom-mended to strengthen RC beams, which are weak in flexure, using 45˚ inclined CFRP sheets.  

scholarly journals Shear Behaviour of RC Beams Strengthened by Various Ultrahigh Performance Fibre-Reinforced Concrete Systems

2020 ◽  
Vol 2020 ◽  
pp. 1-18 ◽  
Author(s):  
Walid Mansour ◽  
Bassam A. Tayeh
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Element Model ◽  
Shear Behaviour ◽  
Fibre Reinforced Concrete ◽  
Rc Beams ◽  
Shear Span ◽  
Depth Ratio ◽  
Normal Strength

This study presents a numerical investigation on the shear behaviour of shear-strengthened reinforced concrete (RC) beams by using various ultrahigh performance fibre-reinforced concrete (UHPFRC) systems. The proposed 3D finite element model (FEM) was verified by comparing its results with those of experimental studies in the literature. The validated numerical model is used to analyse the crucial parameters, which are mainly related to the design of RC beams and shear-strengthened UHPFRC layers, such as the effect of shear span-to-depth ratio on the shear behaviour of the strengthened or nonstrengthened RC beams and the effect of geometry and length of UHPFRC layers. Moreover, the effect of the UHPFRC layers’ reinforcement ratio and strengthening of one longitudinal vertical face on the mechanical performance of RC beams strengthened in shear with UHPFRC layers is investigated. Results of the analysed beams show that the shear span-to-depth ratio significantly affects the shear behaviour of not only the normal-strength RC beams but also the RC beams strengthened with UHPFRC layers. However, the effect of shear span-to-depth ratio has not been considered in existing design code equations. Consequently, this study suggests two formulas to estimate the shear strength of normal-strength RC beams and UHPFRC-strengthened RC beams considering the effect of the shear span-to-depth ratio.

Impact of efficiency and practicality of CFRP anchor installation techniques on the performance of RC beams strengthened with CFRP sheets

2019 ◽  
Vol 46 (9) ◽  
pp. 796-809 ◽  
Author(s):  
Mohammed A. Zaki ◽  
Hayder A. Rasheed
Keyword(s):  
Reinforced Concrete ◽  
Real World ◽  
Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Application Time ◽  
Flexural Capacity ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Real World Applications ◽  
And Performance

Utilizing fiber reinforced polymer (FRP) anchors can enhance the strength and delay the debonding of flexural FRP in strengthened reinforced concrete (RC) beams. In this study, two different techniques are used for applying carbon FRP (CFRP) spike anchors to improve the performance of RC beams strengthened with CFRP sheets. These two techniques are compared with respect to the ease of application, time spent, size of installation team, and performance. The first technique involved applying the CFRP anchors to begin with, then installing CFRP sheets by separating the fibers at the location of anchors. The second technique applied the CFRP sheets first to the beam soffit right after drilling the holes. This was followed by inserting CFRP anchors through the sheets into the prepared holes. The conclusion indicates that the second technique is easier, faster, and more practical in real-world applications. In addition, the use of distributed CFRP anchors increased the flexural capacity of the strengthened beams.

Impact resonance method for damage detection in carbon-fibre-reinforced polymer–strengthened reinforced concrete beams subjected to fatigue and thermal cycling

2008 ◽  
Vol 35 (11) ◽  
pp. 1251-1260 ◽  
Author(s):  
C. Ward ◽  
N. Rattanawangcharoen ◽  
C. Gheorghiu
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Resonance Method ◽  
Experimental Program ◽  
Rc Beams ◽  
Structural Health ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Impact Resonance

Much of North America’s civil infrastructure is rapidly aging and, in some cases, exceeding its design life and load. To combat this, the exploration of simple and effective methods for rehabilitation and structural health monitoring has been receiving much attention in industry and academia. This paper reports on the use of the impact resonance method (IRM) for evaluating the structural health of thermal-cycled reinforced concrete (RC) beams with and without externally strengthened carbon-fibre-reinforced polymer (CFRP) pultruded plates. In the experimental program, 1.2 m long specimens were subjected to 55 thermal cycles ranging from +23 to −18 °C. Fatigue loading consisting of up to two million cycles at high and low stress levels was performed. At pre-determined load cycle intervals, the loading was stopped and the IRM was performed on the specimens. Parameters including the appearance of the fast Fourier transform (FFT) spectrum of the specimens’ vibration, modal fundamental frequencies, and dynamic properties were used to assess damage in the specimen. Conclusions were made regarding the use of the IRM in monitoring the health of strengthened and unstrengthened RC beams subjected to thermal and fatigue cycles.

Experimental Study on RC Beams Strengthened with CFRP Sheets

2011 ◽  
Vol 213 ◽  
pp. 548-552 ◽  
Author(s):  
Jiang Feng Dong ◽  
Qing Yuan Wang ◽  
Ci Chang Qiu ◽  
Dong He
Keyword(s):  
Reinforced Concrete ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Control Beam ◽  
Cfrp Sheets ◽  
Four Point Bending ◽  
Cfrp Sheet ◽  
Cover Thickness

This paper presents the flexural performance of reinforced concrete (RC) beams with rectangular section. Seven RC beams strengthened using carbon fiber reinforced polymer (CFRP) sheets were subjected to four-point bending to investigate the effect of fiber reinforcement on the beams strengthened. The main experimental parameters included in the study are the pre-cracked width, CFRP sheet layers, the longitudinal tensile reinforcement ratio, the shear span ratio, and the concrete cover thickness. In total, seven beams were cast, one beam without any reinforcement as a control beam, two beams strengthened by CFRP sheets without making pre-cracks on the beam and four pre-cracked beams repaired with one layer or two layers CFRP sheets. Test results show the effectiveness and flexural capacity of the CFRP strengthened beams. The flexure enhancement of the CFRP strengthened beams varied between 41.7% and 124.1% over the control beam. This study confirms that the CFRP reinforcing technique significantly enhances the flexural capacity of reinforced concrete beams.

scholarly journals Stiffness and Strength Analysis of Flexural RC beams strengthened with CFRP Sheets Considering the Influence of Pre-cracking

Mechanika ◽  
2020 ◽  
Vol 26 (4) ◽  
pp. 277-284
Author(s):  
Tadas LISAUSKAS ◽  
Mindaugas AUGONIS ◽  
Tadas ZINGAILA ◽  
Mario Rui Tiago ARRUDA
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Experimental Program ◽  
Strength Analysis ◽  
Rc Beams ◽  
Cfrp Sheets ◽  
Good Agreement

                           This paper presents experimental, numerical and analytical analysis of newly cast and pre-cracking flexural reinforced concrete beams strengthened with CFRP. In total, 9 intermediate-scale composite beams were cast and tested using 4-point bending test setup. Midspan deflection, width of the cracks, concrete and CFRP strains were measured during the experimental program. Clear efficiency of composite pre-cracked beams was observed in comparison to newly cast beams: enhanced flexural capacity and increased stiffness after appearance of primary cracks in tension zone. Good agreement was found comparing experimental and theoretical (EC2) deflections of RC beams strengthened with CFRP. However, for more detailed verification, the analysis should be extended with more specimens. The shear stress at the end of CFRP sheets between the concrete and CFRP increased rapidly until reaching maximum slip value, when the reinforced concrete beam strengthened with CFRP reaches 60-90 % utilization of load bearing capacity. All experimental results were compared with numerical and analytical calculations. Experimental, numerical and analytical results were in sufficiently good agreement.

Rehabilitation of Continuous Reinforced Concrete Beams in Shear by External Bonding of Carbon Fiber Reinforced Polymer Strips for Sustainable Construction

2016 ◽  
Vol 708 ◽  
pp. 49-58
Author(s):  
Abdul Aziz Abdul Samad ◽  
Noridah Mohamad ◽  
Noorwirdawati Ali ◽  
J. Jayaprakash ◽  
Priyan Mendis
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Structural Integrity ◽  
Failure Load ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Shear Strengthening ◽  
Reinforced Polymer

To achieve sustainability in construction, the rehabilitation of existing concrete structures is vital in ensuring its structural integrity and longevity. Therefore, an experimental investigation on the shear strengthening of 2-span continuous reinforced concrete (RC) beams wrapped with carbon fiber reinforced polymer (CFRP) strips were conducted. The beam specimens were subjected to four point bending test and loaded incrementally until failure occurs. Different wrapping schemes and layers of CFRP strips were externally bonded within the shear span of the beams. The failure load, modes of failure, its crack patterns, deflection profile were recorded and presented for discussion. From observation, the experimental results indicated good improvement as the shear strengthened beams shows enhanced failure load and shear strength capacity. An improved stiffness and ductility behaviour was also observed compared to the control beam. Comparison with ACI 440 (2008) design provisions for shear strength shows that the prediction values underestimated its experimental results. This indicates that the enhanced shear performances of the 2-span continuous RC beams prove the reliability of CFRP as a strengthening material. Hence, the shear strengthening technique allows the rehabilitation process of existing structural members to improve its structural integrity, longevity and sustainability.

Behaviour of reinforced GFRP bars concrete beams having strengthened splices using CFRP sheets

2021 ◽  
pp. 136943322110015
Author(s):  
Akram S. Mahmoud ◽  
Ziadoon M. Ali
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
New Method ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Strength Capacity ◽  
Cfrp Sheet ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

When glass fibre-reinforced polymer (GFRP) bar splices are used in reinforced concrete sections, they affect the structural performance in two different ways: through the stress concentration in the section, and through the configuration of the GFRP–concrete bond. This study experimentally investigated a new method for increasing the bond strength of a GFRP lap (two GFRP bars connected together) using a carbon fibre-reinforced polymer (CFRP) sheet coated in epoxy resin. A new splicing method was investigated to quantify the effect of the bar surface bond on the development length, with reinforced concrete beams cast with laps in the concrete reinforcing bars at a known bending span length. Specimens were tested in four-point flexure tests to assess the strength capacity and failure mode. The results were summarised and compared within a standard lap made according to the ACI 318 specifications. The new method for splicing was more efficient for GFRP splice laps than the standard lap method. It could also be used for head-to-head reinforcement bar splices with the appropriate CFRP lapping sheets.

scholarly journals Punching Shear Strength of Reinforced Concrete Flat Plates with GFRP Vertical Grids

2021 ◽  
Vol 11 (6) ◽  
pp. 2736
Author(s):  
Min Sook Kim ◽  
Young Hak Lee
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Fiber Reinforced Polymer ◽  
Punching Shear ◽  
Test Results ◽  
Shear Reinforcement ◽  
Flat Plates ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Vertical Grids

In this study, the structural behavior of reinforced concrete flat plates shear reinforced with vertical grids made of a glass fiber reinforced polymer (GFRP) was experimentally evaluated. To examine the shear strength, experiments were performed on nine concrete slabs with different amounts and spacings of shear reinforcement. The test results indicated that the shear strength increased as the amount of shear reinforcement increased and as the spacing of the shear reinforcement decreased. The GFRP shear reinforcement changed the cracks and failure mode of the specimens from a brittle punching to flexure one. In addition, the experimental results are compared with a shear strength equation provided by different concrete design codes. This comparison demonstrates that all of the equations underestimate the shear strength of reinforced concrete flat plates shear reinforced with GFRP vertical grids. The shear strength of the equation by BS 8110 is able to calculate the punching shear strength reasonably for a concrete flat plate shear reinforced with GFRP vertical grids.

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