Investigation on Flexural Behavior of Reinforced Concrete Beams Flexurally Strengthened by Different Methods

2010 ◽  
Vol 163-167 ◽  
pp. 1451-1455
Author(s):  
Gui Bing Li ◽  
Ai Hui Zhang ◽  
Wei Liang Jin

Externally bonding fiber reinforcement polymer (FRP)laminate to the soffit of reinforced concrete (RC) beam is an effective way to increase its flexural strength. However, there is little investigation on flexural behavior of RC beam by side-bonding FRP laminates.To investigate the difference of flexural behavior between soffit-bonding and side-binding FRP laminates RC beams,a total of 9RC beams were tested, including 8 strengthened beams and 1 control beam. The test results showedthat:1) As fiber reinforced concrete, side-bonding FRP laminates can also effectively increase the first crack strength of RC beams.The first crack load improved significantly; 2) side-bonding FRP laminates is not a good method to improve the flexural behavior of RC beam at the yield stage and the post yield stage. 3) Side-bonding of CFRP laminates is a good way for existing RC beams to control its crack width and deflection.

2011 ◽  
Vol 284-286 ◽  
pp. 2521-2525
Author(s):  
Gui Bing Li ◽  
Yu Gang Guo ◽  
Xiao Yan Sun

It is an effective way to increase the flexural performance of reinforced concrete (RC) beam by externally bonding fiber reinforcement polymer (FRP) laminate on the soffit of the beam. However, there is little investigation on flexural behavior of RC beam by side-bonding FRP laminates. To investigate the difference of flexural behavior between soffit-bonding and side-binding FRP laminates RC beams, a total of 9 RC beams were tested, including 8 strengthened beams and 1 control beam. The test results showed that: the first crack load of RC beam strengthened by side-bonding CFRP laminates is much bigger than that of RC beam strengthened by soffit-bonding CFRP laminates.The first crack load of side-bonding CFRP laminates beams improved significantly;side-bonding and soffit-bonding methods have the same effect on the flexural stiffness of RC beams with same quantity of CFRP laminates before tension steel rebar yielding. However, side-bonding can remarkably decrease the crack width and change the crack pattern.Side-bonding of CFRP laminates can extend the pre-crack stage of the strengthened beam;the first yielding load and the ultimate load of beams cannot be improved significantly by side-bonding FRP laminates.


2008 ◽  
Vol 385-387 ◽  
pp. 41-44 ◽  
Author(s):  
Shi Qi Cui ◽  
Jin Shan Wang ◽  
Zhao Zhen Pei ◽  
Zhi Liu

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.


Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1137 ◽  
Author(s):  
Jongho Park ◽  
Sun-Kyu Park ◽  
Sungnam Hong

In this study, nine specimens were experimentally tested to analyze the strengthening efficiency of textile-reinforced mortar (TRM) and the difference in flexural behavior between prestressed and non-prestressed TRM-strengthened reinforced concrete beam. The test results show that TRM strengthening improves the flexural strength of TRM-strengthened reinforced concrete beams with alkali-resistant-(AR-) glass textile as well as that with carbon textile. However, in the case of textile prestressing, the strengthening efficiency for flexural strength of the AR-glass textile was higher than that of the carbon textile. The flexural stiffness of AR-glass textiles increased when prestressing was introduced and the use of carbon textiles can be advantageous to reduce the decreasing ratio of flexural stiffness as the load increased. In the failure mode, textile prestressing prevents the damage of textiles effectively owing to the crack and induces the debonding of the TRM.


2012 ◽  
Vol 6 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Guibing Li ◽  
Yugang Guo ◽  
Xiaoyan Sun

It is an effective way to improve the flexural behavior of reinforced concrete (RC) members by externally bonded carbon fiber reinforcement polymer (CFRP) laminates on the soffit of the members. However, there is little investigation on flexural performance of RC beam flexurally strengthened by side-bonded FRP laminates. To investigate the flexural behavior of RC beams side-bonded CFRP laminates and the difference of RC beams strengthened by soffit-bonded and side-bonded CFRP laminates, a total of 8 CFRP-strengthened beams and 1 control beam were tested. The experimental results show that: 1) the first crack loads of RC beams strengthened by side-bonded CFRP laminates are much higher than that of RC beams strengthened by soffit-bonded CFRP laminates. The first crack loads of side-bonded CFRP laminates beams improved significantly; 2) Side-bonded and soffit-bonded CFRP laminates have almost the same effect on the flexural stiffness of RC beams strengthened with same quantity of CFRP laminates before tension rebar yielding. However, side-bonded CFRP laminates can affect crack width and crack pattern of the strengthened beams, and the pre-crack stage of RC beam by sidebonded CFRP laminates extended remarkably. 3) different to soffit-bonded CFRP laminates RC beams, side-bonded CFRP laminates cannot improve the first yielding and the ultimate load bearing capacity of RC beams.


2010 ◽  
Vol 163-167 ◽  
pp. 3772-3776 ◽  
Author(s):  
Hua Ping Liao ◽  
Shi Sheng Fang

Three reinforced concrete (RC) beams strengthened by high-performance ferrocement and two control specimens without strengthened are investigated when RC beams have low compressive strength. Flexural behaviors of strengthened RC beams with high-performance ferrocement are evaluated based on comparative analysis with RC beams. The strengthening results of steel meshes with U-shape (i.e. ferrocements are put onto the tension face and two profile faces) are analyzed. The flexural capacity, deflection and crack width of RC flexural beams are measured, and then comparative analysis is carried out for deformation performance and law of crack development. The test results show that ferrocement contributes greatly to increase the flexural capacity and raise crack-resisting capacity. The experimental results can provide a theoretical reference for actual engineering designs.


Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2738
Author(s):  
Rendy Thamrin ◽  
Zaidir Zaidir ◽  
Silvy Desharma

In this study, experimental work was carried out on reinforced concrete (RC) beams strengthened with carbon fiber reinforced polymers (CFRP) plates. This study aims to examine the effect of the reinforcement ratio on the flexural behavior of these beams and propose a new model for predicting the debonding moment. Six RC beams consisting of three control beams and three beams strengthened with CFRP plates were tested. The beams were simply supported and loaded with four-point bending. The test variable was the tensile reinforcement ratio (1%, 1.5%, and 2.5%). Analytical prediction using the fiber element method was also carried out to obtain the complete theoretical response of the beam due to flexural loads. The test results show that the reinforcement ratio affected the bending performance of RC beams with CFRP plates. Following this, the experimental data from 60 beam test results from published literature and this study were analyzed. From these data, it was found that the ratio of tensile reinforcement, the ratio of modulus of elasticity of concrete, the modulus of elasticity of the plate, and plate thickness all affect the value of debonding moment. A parametric study using fiber elements and the two-dimensional finite element method was also carried out to confirm the effect of these variables on debonding failure. These variables were then used to develop an equation to predict the debonding moment of RC beams strengthened with CFRP plates, using simple statistical analysis. This analysis resulted in a simple model for predicting the debonding moment. Then the model is entered into a computer program, and the complete response of the cross-section due to debonding failure can be obtained.


2019 ◽  
Vol 27 (3) ◽  
pp. 44-54
Author(s):  
Radhika Sridhar ◽  
Ravi Prasad

AbstractThis paper describes an experimental investigation on mono steel and polypropylene (PP) fiber-reinforced concrete beams. The main aim of this present study is to evaluate undamaged and damaged reinforced concrete (RC) beams incorporated with mono fibers such as steel and PP fibers under free-free constraints. In this experimental work, a total of nine RC beams were cast and analyzed in order to study the dynamic behavior as well as the static load behavior of steel fiber-reinforced concrete (SFRCs) and polypropylene fiber-reinforced concrete (PPFRCs). Damage to the SFRC and PPFRC beams was obtained by cracking the concrete for one of the beams in each set under four-point bending tests with different percentage variations of the damage levels such as 50%, 70% and 90% of the maximum ultimate load. The fundamental natural frequency and damping values obtained through the dynamic tests for the SFRC and PPFRC beams were compared with a control RC beam at each level of damage that had been acquired through static tests. The static experimental test results emphasize that the SFRC beam has attained a higher ultimate load compared with the control RC beam.


2012 ◽  
Vol 535-537 ◽  
pp. 1702-1710 ◽  
Author(s):  
Shuaib H. Ahmad ◽  
Abdullah Bin Najm ◽  
Antonio Naani

In recent decades, use of fibre reinforced polymers (FRP) materials has become very popular for strengthening / re-strengthening of reinforced concrete (RC) structures. This includes flexural and shear strengthening of RC structural members such as slabs, beams and columns.In this study, a computerized analytical model is presented to predict the load-deflection response of flexure critical RC beams externally strengthened with near surface mounted (NSM) CFRP laminates. The analyical model utilizes constitutive material properties of concrete, reinforcing steel, CFRP laminate materials, strain compatibility, sectional analysis to develop moment-curvature relationships, which then are used to generate the load-rotations and load-deflection of the flexure critical RC Beams strengthend with NSM CFRP laminates. For validation of the analytical model, the predictions of the analytical model are compared with the experimental results of flexure critical RC beams strengthened with NSM CFRP laminates and the comparisons are judged to be good.As a part of the experimental investigation of this study, a series of 18 full scale beams Reinforced Concrete Beams strengthened with carbon fiber reinforced polymer (CFRP) laminates will be tested in flexure and shear. The results of flexural tests will be analyzed and compared with the predictions of the analytical model.


2020 ◽  
pp. 136943322097478
Author(s):  
Abu Sayed Mohammad Akid ◽  
Qudrati Al Wasiew ◽  
Md. Habibur Rahman Sobuz ◽  
Touhidur Rahman ◽  
Vivian WY Tam

Fiber-reinforced polymer (FRP) is a revolutionary breakthrough in the history of structural engineering innovation due to its unique characteristics to strengthen and repair the deficient reinforced concrete structures. This paper aimed at evaluating the flexural characteristics of jute fiber reinforced polymer (JFRP) bonded reinforced concrete beams. The influence of the test variables comprised of strengthening scheme and corrosion rate for reinforced concrete (RC) beams. The experimental study comprised of casting six RC beams and testing them in flexure loading. To determine the flexural response of RC beams, three beams were fabricated with JFRP laminate having a level of corrosion of 0%, 7.5%, and 15%, whereas three beams were designated as control beams having same corrosion levels with no JFRP. Test results indicated that all JFRP strengthened beams exhibited increased ultimate load, yield load, first cracking load, and lower ductility index compared to control beams. The results also revealed that JFRP strengthening technique improved the flexural strength of the corroded beams efficiently, albeit the ultimate load of the beams diminished with higher corrosion level. Analytical calculations were carried out for quantifying the flexural characteristics and mass loss of beams which provided a good agreement with the test results.


Author(s):  
Nguyen Trung Hieu ◽  
Nguyen Van Tuan

The elasto-plastic characteristics of plain concrete are inevitably affected by the loading rate. This paper presents an experimental investigation on the effect of loading rate on flexural behavior of concrete and reinforced concrete (RC) beams, which was carried out with Walter+bai electro-hydraulic servo system. Three-point bending tests on 100 × 100 × 400 mm prismatic concrete samples and 80 × 120 × 1100 mm RC beams with different displacement controlled loading rates of 0.01 mm/min, 0.1 mm/min, and 3 mm/min were imposed. Based on the test results, the effects of loading rates on the load-displacement curve, cracking, and ultimate load-carrying capacities of RC beams were evaluated.


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