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.

scholarly journals Experimental and Numerical Investigation on Shear Retrofitting of RC Beams by Prefabricated UHPFRC Sheets

2016 ◽  
Vol 2 (5) ◽  
pp. 168-179
Author(s):  
Kian Aghani ◽  
Hassan Afshin
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Fem Analysis ◽  
Fiber Reinforced Concrete ◽  
Bending Test ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Externally Bonded ◽  
High Performance Fiber ◽  
Bending Capacity

Different methods are used for retrofitting RC members. One of the new methods in this field is using externally bonded fiber-reinforced Concrete (FRC) sheets in order to increase RC member’s shear and flexural strength. In this study, applicability of ultra-high performance fiber-reinforced concrete sheets in shear and flexural retrofitting of RC beams was investigated. In total, eight RC beams (dimensions 10×20×150 cm) with two different bending capacity and lack of shear strength were used and were tested in 3-points bending test. Of these, four were control beams and four were retrofitted with laterally bonded UHPFRC sheets. Dimensions of the sheets used for retrofitting were (3×15×126 cm). Also FEM analysis was used to model the effect of The method. the results show that this method can be well used for retrofitting RC beams. In this method the way of connecting sheets to beam’s surfaces has a fundamental role in behavior of retrofitted beams.

FINITE ELEMENT MODELLING OF 2-SPAN CONTINUOUS RC BEAMS SHEAR STRENGTHENED AND SHEAR REPAIRED WITH CFRP STRIPS

2016 ◽  
Vol 78 (5) ◽  
Author(s):  
Abdul Aziz Abdul Samad ◽  
Noorwirdawati Ali ◽  
Noridah Mohamad ◽  
J. Jayaprakash ◽  
Tuan Duc Ngo ◽  
...  
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Shear Behaviour ◽  
Rc Beams ◽  
Shear Strengthening ◽  
Existing Structures ◽  
Finite Element Software ◽  
Externally Bonded ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

Strengthening of reinforced concrete (RC) continuous beams in shear have received very little attention among researchers even though most existing structures are in the form of continuous condition such as part of a floor-beam system. Therefore, in order to address the gap, a study on shear strengthening and shear repair of reinforced concrete continuous beam using Carbon Fibre Reinforced Polymer (CFRP) strips was conducted [15].  The validation of the experimental results was conducted with a simulation study using a finite element software ATENA v4 [16].  The research variables were number of layers of CFRP strips (one or two layers), wrapping schemes (four sides or three sides) and orientation of CFRP strips (0/90 or 45/135 degree’s). From the analysis of the finite element results, ATENA shows it has successfully simulated the shear behaviour of strengthened and repaired of 2-span continuous RC beams externally bonded by CFRP strips. 

scholarly journals Mechanical Behavior and Chloride Penetration of Precracked Reinforced Concrete Beams with Externally Bonded CFRP Exposed to Marine Environment

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Yan Xie ◽  
Kunhua Guan ◽  
Lei Zhan ◽  
Qichen Wang
Keyword(s):  
Reinforced Concrete ◽  
Marine Environment ◽  
Chloride Penetration ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Chloride Diffusion ◽  
Accelerated Ageing ◽  
Rc Beams ◽  
Cfrp Sheets ◽  
Externally Bonded

Cracked reinforced concrete (RC) beams can be repaired effectively by using externally bonded CFRP sheets. However, when the strengthened beams are subjected to marine environment, long-term performance will be affected by the material and the interface deterioration of concrete and CFRP. Therefore, to evaluate the service life of the strengthened beams, this study investigates the behavior of precracked RC beams strengthened with CFRP sheets exposed to marine environment. Accelerated ageing experiments were carried out by exposing specimens to cyclic wetting in sea water and drying in 40°C air for 3 months and 6 months, respectively. After the environment exposure, four-point bending test was conducted and then the diffusion of chlorides in the strengthened beams was analysed. The results show that the bonding behavior of the adhesive was weakened and the ductility of the strengthened beams was slightly reduced due to the marine environment. But there is no obvious strength difference between the strengthened beams suffered from marine environment for 3 months and 6 months. Besides, the precracks in the RC beams accelerated the chloride diffusion, while CFRP bonding reduced the chloride penetration. In addition, NEL method was employed to validate the effect of the cracks on chloride permeability. The results showed that the chloride diffusion coefficients increased with the depth of the cracks.

Effective Method of Repairing RC Beam Using Externally Bonded Steel Plate

2014 ◽  
Vol 567 ◽  
pp. 399-404 ◽  
Author(s):  
Md Ashraful Alam ◽  
Ali Sami Abdul Jabbar ◽  
Mohd Zamin Jumaat ◽  
Kamal Nasharuddin Mustapha
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Steel Plate ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Rc Beam ◽  
External Reinforcement ◽  
Externally Bonded ◽  
Damaged Beams

Repair of reinforced concrete beam with externally bonded steel plate or fibre reinforced polymer (FRP) laminate is becoming both environmentally and economically preferable rather than replacement of deficient beam. The well known advantages of external reinforcement over other methods include; low cost, ease of maintenance and the ability to strengthen part of the structure while it is still in use. The disadvantage of this method, however, is the premature debonding of the externally bonded strips which is brittle and undesired mode of failure. It is also known that debonding of the externally bonded steel plates prevents the reinforced concrete (RC) beam from reaching its full strengthening capacity. The aim of this study was to increase the scientific understanding on the behaviour of damaged reinforced concrete beams strengthened and/or retrofitted for shear using vertical steel plate fixed with adhesive and steel connectors to eliminate or delay debonding failure. Four reinforced concrete beam specimens were prepared to investigate the effects of connectors in preventing or delaying premature debonding of shear strips to restore the capacities of fully damaged beams. Three damaged beams have been repaired and strengthened with steel plates and loaded monotonically up to the maximum load capacities in order to define load–deflection relationship. It is concluded that the repairing of severely shear-damaged RC beams with steel plates by using steel and adhesive connectors can fully restore the original shear capacities of the beams.

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 Debonding-Related Strain Limits for Externally Bonded FRP Sheets in Flexurally Strengthened Reinforced Concrete Beams

2013 ◽  
Vol 7 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Guibing Li ◽  
Aihui Zhang ◽  
Yugang Guo
Keyword(s):  
Reinforced Concrete ◽  
Tensile Strain ◽  
Concrete Beams ◽  
Experimental Tests ◽  
Critical Issue ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Externally Bonded ◽  
Strengthening Technique ◽  
Code Provisions

Debonding problems of externally bonded fiber reinforced polymer (FRP) sheets in flexurally FRP-strengthened reinforced concrete (RC) beams have been a concern and a research challenge since their application of this strengthening technique. Intermediate crack induced debonding is the most common failure mode which is that the debonding initiates at the critical flexural-shear or flexural cracks and propagates towards the direction of moment decrease. To mitigate debonding failure, most Codes and proposed models take the method by limiting the allowable tensile strain in FRP laminates. This paper presents experimental tests of concrete beams flexurally strengthened with externally bonded CFRP sheets to investigate debonding initiation and tensile strain of FRP laminates. The allowable tensile strain of FRP sheets in flexurally FRP-strengthened RC beams proposed by prevalent Code provisions and models was assessed based on the data obtained from experimental programs. It has beenshown that the allowable tensile strains provided by these provisions and models have a great difference with that of experimental results and exhibit a high level of dispersion. Furthermore, the FRP laminates of most tested RC beams were debonded before reaching the proposed allowable tensile strain. The Code provisions and models are inadequate to effectively prevent intermediate crack induced debonding failure in flexurally FRP-strengthened RC members. This is known to be a critical issue in engineering design and application of RC beams flexurally strengthened by FRP sheets.

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 Analysis for Reinforced Concrete Beams with Circular Openings in Flexural and Shear Zones Strengthened by Steel Plates

2018 ◽  
Vol 23 (2) ◽  
pp. 31-48
Author(s):  
Ahmed Ali AL-Dhabyani ◽  
Abdulwahab AL-Ansi
Keyword(s):  
Reinforced Concrete ◽  
Carrying Capacity ◽  
Ultimate Load ◽  
Shear Zones ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Load Carrying Capacity ◽  
Rc Beams ◽  
Study Results ◽  
Load Carrying

In the modern building construction, openings in beams are necessary to accommodate several service pipes and ducts. Due to these openings, high stress concentration occurs at its edges. Local cracks also appear around the openings as a result of the reduction in the beam stiffness, the load carrying capacity and the shear capacity. There are many studies which were conducted to develop and test different strengthening methods for the beams opining to increase the ultimate load capacity of the beams. However, from a practical point of view, it is better to have one strengthening method having the same specifications to be used in both; shear and flexural zones for circular opining beams in buildings. In spite of the prior studies, no study has addressed this issue; therefore, there is a need to study such a case. In this paper, an analytical study was conducted to investigate the behavior of the reinforced concrete (RC) beams with circular openings in flexural and shear zones strengthened by steel plates. A 3D FE modeling (ABAQUS 6.12) software was used to simulate five different specimens of RC beams. The study results showed that when the openings were strengthened by steel plates, the ultimate load carrying capacity increased, but the deflection was decreased when compared to the openings without strengthening. In addition, the model reliability was verified via good agreements between the experimental and numerical results.

Nonlinear analysis of RC beams strengthened by externally bonded plates

2007 ◽  
Vol 4 (2) ◽  
pp. 119-134
Author(s):  
Jae-Guen Park ◽  
Kwang-Myong Lee ◽  
Hyun-Mock Shin ◽  
Yoon-Je Park
Keyword(s):  
Nonlinear Analysis ◽  
Rc Beams ◽  
Externally Bonded
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