scholarly journals Flexural Capacity of RC Beams with Opening Strengthened using CFRP Sheet

2021 ◽  
Vol 1200 (1) ◽  
pp. 012017
Author(s):  
M M Jusoh ◽  
N Ali ◽  
N A Abdul Hamid ◽  
N Salleh ◽  
S R Abdullah ◽  
...  
Keyword(s):  
Point Load ◽  
Concrete Cover ◽  
Rc Beam ◽  
Circular Opening ◽  
Flexural Capacity ◽  
Flexural Failure ◽  
Cfrp Sheet ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Strengthened Beam

Abstract The use of Carbon Fibre Reinforced Polymer (CFRP) in strengthening has found to be an effective material which comprises of characteristic that comply to the requirement of structural component. CFRP was selected as strengthening material because of the capability to resist the corrosion and could regain the loss capacity due to presence of opening. The opening in structural member was essential in order to provide the route for the utility pipe, air conditioning, water supply and electrical conduit. However, the presence of opening has contributed to the reduction of stiffness, increase of deflection and extension of cracking of the beams. Therefore, this research was conducted to overcome the problem where the flexural capacity and the load deflection behavior of RC beam with opening strengthened by using CFRP sheet was analyzed. A total of five beam have been casted and tested. The specimens consist of beams with different type of opening which are rectangular and circular. The size of all specimen was 200 mm width, 250 mm height and 2000 mm for total length. The size of circular opening was 150 mm in diameter while rectangular opening was 150 x 200 mm. Bi-directional CFRP sheet were applied at the opening area as strengthening material and all beams were tested until failure. All of specimen were produced with the designed using 30 mm concrete cover, 6 mm link size and 10mm main bar size. The testing of specimens comprises of cube compressive test and four-point load for beam testing in order the determine the flexural strength of RC beam. The result from this research indicated that strengthened beam with circular opening which is SBOC-BI exhibit the highest ultimate load of 71.5 kN with flexural failure as the mode of failure.

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.

Strengthening of the Frame Structure at the Timisoreana Brewery, Romania

2010 ◽  
pp. 57-80
Author(s):  
Corneliu Bob ◽  
Sorin Dan ◽  
Catalin Badea ◽  
Aurelian Gruin ◽  
Liana Iures
Keyword(s):  
Reinforced Concrete ◽  
Load Resistance ◽  
Concrete Cover ◽  
Frame Structure ◽  
Reinforced Concrete Structure ◽  
Existing Structures ◽  
Concrete Carbonation ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Lateral Load Resistance

<p>Many structures built in Romania before 1970 were designed for gravity loads with inadequate lateral load resistance because earlier codes specified lower levels of seismic loads. Some of these structures are still in service beyond their design life. Also, some deterioration was observed in existing structures due to the actions of different hazard factors. This paper presents the case study of a brewery with reinforced concrete framed structure of five storeys and a tower of nine storeys, which has been assessed and strengthened. The brewery and the tower were built in 1961 and an extension in 1971. An assessment performed in 1999 showed up local damages at slabs, main girders, secondary beams, and columns; concrete carbonation; concrete cover spalled over a large surface; complete corrosion of many stirrups and deep corrosion of main reinforcement; and some broken reinforcement. Such damage was caused by salt solution, CO2, relative humidity RH 80%, and temperatures over 40◦C. Also, inadequate longitudinal reinforcement was deduced≈ from the structural analysis. The initial design, done in 1960, was according to the Romanian codes of that time with provisions at low seismic actions. The structural system weakness is due to present-day high seismic actions. The rehabilitation of the reinforced concrete structure was performed by jacketing with reinforced concrete for the main and secondary beams and columns. In 2003, due to continuous operation and subsequent damage of the structure, a new assessment was required. It was found that some beams and one column were characterized by inadequate main and shear reinforcement as well as corrosion of many stirrups at beams. The strengthening solution adopted was based on carbon fibre reinforced polymer composites for beams and column.</p>

scholarly journals Experimental investigation of reinforced concrete beams with and without CFRP wrapping

2012 ◽  
Vol 20 (3) ◽  
pp. 15-26
Author(s):  
K.V. Venkatesha ◽  
S.V. Dinesh ◽  
K. Balaji Rao ◽  
B.H. Bharatkumar ◽  
S.R. Balasubramanian ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Shear Failure ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Experimental Investigations ◽  
Flexural Failure ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Cfrp Wrapping

AbstractThis paper presents the results of experimental investigations on six reinforced concretebeams, with three different shear span-to-depth ratios, which were tested under two-pointloading. The aim of the work was to study the efficacy of Carbon Fibre Reinforced Polymer(CFRP) strips in enhancing shear capacity and/or changing the failure mode from brittleshear failure to ductile flexural failure. The results of the study indicate that while thereis a marginal increase in first crack and ultimate loads, it is possible to achieve a changein the failure mode, and the monitored strain gauge data can be used to explain the failurepattern observed.

Evaluation of Bonding between High Modulus CFRP Sheet and Steel after Environmental Exposure and Fatigue Loading

2014 ◽  
Vol 891-892 ◽  
pp. 143-148
Author(s):  
Hong Bo Liu ◽  
Daniel Borrie ◽  
Xiao Ling Zhao ◽  
Yu Bai ◽  
R.K. Singh Raman
Keyword(s):  
Failure Modes ◽  
Sea Water ◽  
Fatigue Loading ◽  
Reinforced Polymer ◽  
Cfrp Sheet ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Loading Tests ◽  
Number Of Cycles ◽  
Steel Joints

This study investigated the effects of fatigue loading and corrosive environment on bonding strength and failure modes of Carbon Fibre Reinforced Polymer (CFRP)-laminated steel. A series of tests on CFRP bonded steel plate joints was conducted. The joints were immersed in the temperature controlled sea-water with a preload. After immersions for one and six months, they were subjected to cyclic loading for a pre-set number of cycles, and then tensioned to failure. The effect of fatigue loading alone was studied by the authors in the past. In the present study, the results of the cyclic and static loading tests were compared. The comparisons between the current and previous results have provided data on the durability of CFRP/steel joints under this environmental condition.

Concrete cover separation of reinforced concrete beams strengthened with near-surface mounted method: Mechanics based design approach

2019 ◽  
Vol 22 (7) ◽  
pp. 1739-1754
Author(s):  
Ahmad Azim Shukri ◽  
Zainah Ibrahim ◽  
Huzaifa Hashim
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibre ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Near Surface Mounted ◽  
Concrete Cover Separation

The primary mode of premature failure for near-surface mounted strengthened beams is the concrete cover separation. Due to its complexity, most of the prediction methods for concrete cover separation tend to be empirical based, which can limit their usage to specific near-surface mounted strengthening configurations. In response to that, this article presents a mechanics-based design which uses the moment-rotation approach and the global energy balance approach which is less reliant on empirical formulations, as the mechanics of reinforced concrete beam such as tension stiffening and propagation of concrete cover separation debonding crack are directly simulated rather than empirically derived. The proposed design procedure was validated against published experimental results of reinforced concrete beams strengthened with near-surface mounted carbon fibre–reinforced polymer bars, near-surface mounted carbon fibre–reinforced polymer strips or side-near-surface mounted carbon fibre–reinforced polymer bars and show good accuracy. As it is less reliant on empirical formulations, the proposed design procedure should be applicable to various near-surface mounted reinforcement configurations and materials.

Effects of Eccentric Load on Un-Strengthen and CFRP Strengthened RC Beams

2014 ◽  
Vol 935 ◽  
pp. 229-232 ◽  
Author(s):  
Muhammad Imran ◽  
Nasir Shafiq ◽  
Ibrisam Akbar
Keyword(s):  
Experimental Program ◽  
Rc Beam ◽  
Rc Beams ◽  
Eccentric Load ◽  
Load Effect ◽  
Load Carrying ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Group A ◽  
Group B

CFRP strengthened reinforced concrete (RC) beams are usually tested under either three points or four point concentric loads; the effect of eccentricity is neglected in many studies. In this experimental program eight RC beams tested in two groups, GROUP ‘A’ & ‘B’. In group ‘A’ four RC beam tested, one control beam tested under concentric load and three under the eccentricity of 40, 60 and 80 mm respectively. The remaining four RC beams in group ’B’ strengthened using carbon fibre reinforced polymer (CFRP) strip and tested under the 60mm eccentricity. The experiment has confirmed the behaviour transformation from flexure failure to local failure due to variation in eccentricity. Therefore, the effects of eccentricity cannot be neglected and required special consideration before applying strengthening scheme on RC beam. The RC beams strengthen using CFRP have the ability to enhanced the load carrying capacity of beams tremendously, but the eccentric load effect on ductility, and failure mode of RC beams.

scholarly journals Finite element modeling of flexural behavior of reinforced concrete beams externally strengthened with CFRP sheets

2021 ◽  
Vol 16 (59) ◽  
pp. 62-77
Author(s):  
Mahmoud Madqour ◽  
Khalid Fawzi ◽  
Hilal Hassan
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Element Model ◽  
Point Load ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Flexural Capacity ◽  
Cfrp Sheets ◽  
Cfrp Sheet

In this research, the finite element method is used to develop a numerical model to analyse the effect of the external strengthening of reinforced concrete beams by using carbon Fiber Reinforced Polymer (CFRP) sheets. A finite element model has been developed to investigate the behavior of RC beams strengthened with CFRP sheets by testing nineteen externally simple R.C. beams, tested under a four-point load setup until failure. Various CFRP systems were used to strengthen the specimens.  The numerical results using the (ANSYS workbench v.19.1) were calibrated and validated with the experimental results.  The research results indicate a significant improvement in the structural behavior of the specimens strengthened using CFRP sheet systems. Then the validated model investigated the effect of the width of CFRP sheets, no of layers, and CFRP size on the behavior of strengthened R.C. beams. Results of this numerical investigation show the effectiveness of increase CFRP width to improve the flexural capacity of R.C. beams. An increase in the flexural capacity up to 100 % compared to the control beam.

Flexural Characteristics of Concrete Beams Reinforced with a New Type of GFRP Bar

2009 ◽  
Vol 17 (4) ◽  
pp. 253-264 ◽  
Author(s):  
Hongseob Oh ◽  
Do Young Moon ◽  
Goangseup Zi
Keyword(s):  
Theoretical Model ◽  
American Concrete Institute ◽  
Concrete Cover ◽  
Flexural Capacity ◽  
Concrete Members ◽  
Reinforced Polymer ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced ◽  
New Type

Beam tests were conducted to investigate the characteristics of a newly developed type of glass fibre-reinforced polymer (GFRP) rebar as reinforcement in flexural concrete members. Nine beams over-reinforced with different types of rebar, and with varying reinforcement ratios and depths of concrete cover, were monotonically loaded up to failure. Results were characterised by failure mode, moment–curvature, flexural capacity, load–deflection, and crack width. The test results were compared with the theoretical model and the American Concrete Institute design guide, which showed that the performance of the newly- developed GFRP rebar was comparable to commercially available GFRP rebars. In addition, a theoretical model for moment–curvature and an equation for predicting the flexural capacity of the beams with multiple layers of GFRP rebar are presented, based on the experimental observations.

scholarly journals An Experimental Study on Concrete Flat Slabs Prestressed with Carbon Fibre Reinforced Polymer Sheets

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Yin Shen ◽  
Shaohui Lu ◽  
Fangyuan Li
Keyword(s):  
Carbon Fibre ◽  
Prestressed Concrete ◽  
Utilization Efficiency ◽  
Cfrp Sheets ◽  
Flat Slabs ◽  
Reinforced Polymer ◽  
Cfrp Sheet ◽  
Carbon Fibre Reinforced Polymer ◽  
Anchoring System ◽  
Fibre Reinforced Polymer

Carbon fibre reinforced polymer (CFRP) is currently used to reinforce buildings in civil engineering in the common forms of sheets, while the utilization efficiency of a CFRP materials greatly decreased when the CFRP material is directly bonded to the structure because of the lack of the effect of the exertion of a prestress. A paper spool-inspired anchoring method is proposed to overcome the shearing problem in the anchoring system through the friction between layers. Anchoring and jack-up tensioning devices for CFRP sheets are also designed and produced. A prestress is successfully applied to single and multiple CFRP sheets (80% tensioning strength is achieved), thus verifying the tensioning effect of the prestress. Based on these results, prestressed concrete flat slabs were designed with pretensioned CFRP sheets. The corresponding mechanical properties of the concrete flat slabs are tested to verify the feasibility of using CFRP sheets to apply a prestress. The results show that the uniformity of the fibre stress during the tensioning of the CFRP sheet is the key to the success of the application of the prestress.

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.

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