scholarly journals Flexural Performance of RC Beams Strengthened with Externally-Side Bonded Reinforcement (E-SBR) Technique Using CFRP Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2809
Author(s):  
Md. Akter Hosen ◽  
Fadi Althoey ◽  
Mohd Zamin Jumaat ◽  
U. Johnson Alengaram ◽  
N. H. Ramli Sulong
Keyword(s):  
Absorption Capacity ◽  
Experimental Program ◽  
Rc Beams ◽  
Rc Structures ◽  
Functional Changes ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Flexural Performance ◽  
Design Loads ◽  
Predicted Values

Reinforced concrete (RC) structures necessitate strengthening for various reasons. These include ageing, deterioration of materials due to environmental effects, trivial initial design and construction, deficiency of maintenance, the advancement of design loads, and functional changes. RC structures strengthening with the carbon fiber reinforced polymer (CFRP) has been used extensively during the last few decades due to their advantages over steel reinforcement. This paper introduces an experimental approach for flexural strengthening of RC beams with Externally-Side Bonded Reinforcement (E-SBR) using CFRP fabrics. The experimental program comprises eight full-scale RC beams tested under a four-point flexural test up to failure. The parameters investigated include the main tensile steel reinforcing ratio and the width of CFRP fabrics. The experimental outcomes show that an increase in the tensile reinforcement ratio and width of the CFRP laminates enhanced the first cracking and ultimate load-bearing capacities of the strengthened beams up to 141 and 174%, respectively, compared to the control beam. The strengthened RC beams exhibited superior energy absorption capacity, stiffness, and ductile response. The comparison of the experimental and predicted values shows that these two are in good agreement.

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 Experimental assessment of the performance of reinforced concrete beams strengthened with carbon fiber reinforced polymer laminates

2020 ◽  
Vol 39 (1) ◽  
pp. 105-112
Author(s):  
N. Yusuf ◽  
J.M. Kaura ◽  
A. Ocholi ◽  
M. Abbas
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Rc Beams ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Flexural Performance ◽  
Load Carrying ◽  
Ultimate Load Carrying Capacity

In this study, experimental research is carried out to assess the flexural performance of RC beams strengthened with different amount of CFRP laminates at the tension face. Twelve rectangular RC beams were fabricated and three are un-strengthened and used as reference beams and the remaining nine are strengthened with different amount of CFRP varying from single to triple layers and all are tested to failure under three points bending test. The increase of ultimate strength provided by the bonded CFRP laminates is assessed and failure modes is identified and compared to the un-strengthened RC beams. The results indicated that the flexural capacity of the beams was significantly improved as the amount of the laminates increases that ranged from 20% to 52% increased for single to triple layers laminates. It is concluded that the attachment of CFRP laminates has substantial influence on the performance of CFRP strengthened RC beams. Based on the observed results, recommendations are made that externally application of CFRP laminates can be used for a significant enhancement of the strength deficient RC beams in increasing the ultimate load carrying capacity. Keywords: CPRP laminate, Reinforced concrete, ductility, index, epoxy resin, flexural strengthening

scholarly journals TEXTILE REINFORCED MORTAR BASED FLEXURAL STRENGTHENING OF REINFORCED CONCRETE BEAMS

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Muhammad Imran Rafiq ◽  
Ameer Baiee
Keyword(s):  
Reinforced Concrete ◽  
Basalt Fiber ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Rc Beams ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Strengthening Technique ◽  
Textile Reinforced Mortar

Strengthening of reinforced concrete (RC) structures is often necessary due to the change of using or to enhance the strength of deteriorated existing RC structures attributed to aging and environmental effects. Interfacial bond between the existing RC member and the strengthening layer is known to be the main factor for any successful strengthening technique. This study investigates the efficiency of utilizing high strength cementitious connectors in preventing the debonding of textile reinforced mortar (TRM) strengthening layer from substrate concrete of RC beams. An experimental program is developed to investigate the effect of strength of mortars and the distribution of cementitious connectors on the behavior of the strengthened beams. TRM comprising eight and sixteen textile basalt fiber layers were utilized in these experiments. The results demonstrate the effectiveness of cementitious connectors on the failure mode of strengthened beams by means of controlling the debonding of TRM. The increase in cracking and ultimate loads is demonstrated due to the strengthening of RC beams using TRM.

Flexural strengthening of pre-cracked RC slabs with prestressed NSM CFRP laminates and evaluation of strain loss

2021 ◽  
pp. 136943322110105
Author(s):  
M.R. Mostakhdemin Hosseini ◽  
Salvador J.E. Dias ◽  
Joaquim A.O. Barros
Keyword(s):  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Transfer Length ◽  
Rc Structures ◽  
Cracked Concrete ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Load Carrying ◽  
Rc Slabs

The strengthening intervention of RC structures often involves already cracked concrete. To evaluate the effect of the level of damage prior to the strengthening (pre-cracks) on the behavior of the flexurally strengthened RC slabs with prestressed NSM CFRP laminates, an experimental research was carried out. Two pre-cracking levels of damage were analyzed and, for each one, three levels of prestress were tested (0%, 20% and 40%). The obtained results showed that the strengthening of damaged RC slabs with prestressed NSM CFRP laminates results in a significant increase on the load carrying capacity at serviceability limit states. Pre-cracked RC slabs strengthened with prestressed NSM CFRP laminates presented a load carrying capacity almost similar to the corresponding uncracked strengthened slabs. To determine the effective prestress level in CFRP laminates, the variation of strain over the length of the CFRP and over time was experimentally recorded. The prestress transfer length was also evaluated. The experimental results revealed that the transfer length of CFRP laminates was less than 150 mm, and the maximum value of strain loss out of transfer length (around 14%) was measured close to the cracked section of the damaged RC slabs. Significant part of strain loss in CFRP laminates occurred during 24 h after releasing the prestress load.

scholarly journals Flexural strengthening of RC beams with NSM CFRP laminates

2020 ◽  
Vol 323 ◽  
pp. 01010
Author(s):  
Damian Szczech ◽  
Łukasz Krawczyk ◽  
Renata Kotynia
Keyword(s):  
Reference Beam ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Carbon Fibre Reinforced Polymer ◽  
Bottom Side ◽  
Cracking Pattern

The paper presents test results of reinforced concrete beams flexurally strengthened with Carbon Fibre Reinforced Polymer (CFRP) laminates using the Near Surface Mounted (NSM) technique. RC beams with a cross section of 200 x 400 mm were tested in four-point bending. Two RC beams were strengthened with one NSM CFRP laminate installed into the concrete cover on the bottom side of the beam. One of the beams was strengthened under the self-weight (B10.1) and the second one under initial preloading equal to 83% of the ultimate load of the reference beam (B10.1o). Failure mechanisms, cracking pattern and flexural behaviour of the beams are described in the paper. All the strengthened beams failed by rupture of the CFRP laminates followed by the internal steel reinforcement yielding. High strengthening efficiency of the NSM strengthening was confirmed by 109% and 130% when compared with the non-strengthened beam, respectively for beams B10.1 and B10.1o.

scholarly journals Behaviour of RC structures strengthened with prestressed CFRP laminates: a numerical study

2019 ◽  
Author(s):  
José Sena-Cruz ◽  
Luís Correia ◽  
Paulo França
Keyword(s):  
Numerical Study ◽  
Shear Stresses ◽  
Premature Failure ◽  
Rc Structures ◽  
Cfrp Laminate ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Externally Bonded ◽  
Fibre Reinforced Polymer ◽  
Rc Slabs

<p>The externally bonded reinforcement (EBR) technique is one of the most widely used strategies for the flexural strengthening of reinforced concrete (RC) with fibre reinforced polymer (FRP) materials. The EBR technique offers several structural advantages when the FRP material is prestressed. The development of high shear stresses at the ends of the prestressed FRP material can cause premature FRP peeling-off failure. This premature failure can be delayed or even avoided with the use of special end-anchorage systems, like the mechanical anchorage (MA) system and the gradient anchorage (GA) system. This paper presents an experimental and a numerical study on RC slabs strengthened in flexure with prestressed carbon FRP (CFRP) laminate strips, namely: (i) one reference slab; (ii) one slab strengthened with non- prestressed externally bonded CFRP (EB-CFRP) laminate; (iii, iv) and two slabs strengthened with prestressed EB-CFRP laminates using the MA and GA systems. The performance of these simulations was compared with results of the slabs experimentally tested up to failure. Subsequently, these models were used on a parametric study that intended to investigate the influence of different parameters affecting the behaviour of the slabs strengthened with prestressed EB-CFRP laminates.</p>

scholarly journals Energy Absorption Evaluation of CFRP-Strengthened Two-Spans Reinforced Concrete Beams under Pure Torsion

2019 ◽  
Vol 5 (9) ◽  
pp. 2007-2018 ◽  
Author(s):  
Ammar N. Hanoon ◽  
Ali A. Abdulhameed ◽  
Haider A. Abdulhameed ◽  
Saad K. Mohaisen
Keyword(s):  
Reinforced Concrete ◽  
Energy Absorption ◽  
Concrete Beams ◽  
Absorption Capacity ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Rc Beams ◽  
Pure Torsion ◽  
Energy Absorption Capacity ◽  
Strengthened Beam

For more than a decade, externally bonded carbon fiber reinforced polymer (CFRP) composites successfully utilized in retrofitting reinforced concrete structural elements. The function of CFRP reinforcement in increasing the ductility of reinforced concrete (RC) beam is essential in such members. Flexural and shear behaviors, ductility, and confinement were the main studied properties that used the CFRP as a strengthening material. However, limited attention has been paid to investigate the energy absorption of torsion strengthening of concrete members, especially two-span concrete beams. Hence, the target of this work is to investigate the effectiveness of CFRP-strengthening technique with regard to energy absorption of two-span RC beams subjected to pure torsion. The experimental program comprises the investigation of two groups; the first group comprises eight un-strengthened beam specimens, while the second group consists of eight strengthened beam specimens tested under torsional forces. The energy absorption capacity measured from the area under the curve of torque-angle of twist for tested beams. Two parameters were studied, the influence of concrete compressive strength and the angle of a twist. Experimental results indicated that all beams wrapped with CFRP sheet display superior torsional energy absorption capacity compared to the control specimens. The energy absorption may consider as a safety index for the torsional capacity of two-span RC beams under service loadings. Therefore, it is possible to avoid structural as well as material damages by understanding the concept of energy absorption that is one of the important experimental findings presented in this study.

scholarly journals Flexural strengthening of RC beams by using a near surface mounted T-section profiles

2014 ◽  
Vol 13 (3) ◽  
pp. 071-078
Author(s):  
Szymon Chołostiakow ◽  
Renata Kotynia
Keyword(s):  
Reference Beam ◽  
Concrete Surface ◽  
Experimental Program ◽  
Rc Beams ◽  
Test Results ◽  
Near Surface ◽  
Flexural Strengthening ◽  
Existing Structures ◽  
Near Surface Mounted ◽  
Strengthening Technique

The paper presents test results of an experimental program of four full-scale RC beams, strengthened in flexure with T-section carbon fiber reinforced polymer (CFRP) profiles and two reference beams subjected to a six point bending. The novel shape of CFRP profile combines both the near surface mounted (NSM) and externally bonded (EB) strengthening systems. The application of the CFRP profiles consisted of gluing both the web and the flange of the profile to the concrete surface. RC beams made of the same concrete class were differed by the internal steel reinforcement ratio and in a number of applied profiles. Efficiency of this new strengthening product was determined by comparison of the strengthened and non-strengthened RC beams. An increase of the CFRP-concrete bond area and high stiffness of the T-section profiles significantly improved the strengthening ratio (up to 130% of the reference beam) and reduced the maximum mid-span deflection (ranged of 70-80%) of the non–strengthened beams. The CFRP strain utilisation equal to 67% of the tensile strain corresponded to the maximum CFRP strains equal to 0,73%. The promising test results exhibit this system as a very attractive proposal of new strengthening technique used for field applications of the  existing structures.

Numerical Capacity Examination of RC Beams Subjected to Partial Rebar Corrosion

2016 ◽  
Vol 707 ◽  
pp. 60-71 ◽  
Author(s):  
Yi Zhou Yang ◽  
Lu Kuan Qi
Keyword(s):  
Steel Corrosion ◽  
Absorption Capacity ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Energy Absorption Capacity ◽  
Rc Structures ◽  
Finite Element Software ◽  
Corrosion Rates ◽  
The Relationship ◽  
Good Agreement

Steel Corrosion affects severely on the life and durability of RC structures. In order to investigate the relationship between partial corrosion of RC beams and its cracking morphology and flexural capacity, based on experimental data, RC partial corrosion beam models are simulated using finite element software to model the flexural cracks and capacity of corroded RC beam under different corrosion rates. The results of compared analysis with experiment are presented: with the increase of the corrosion rate, the cracking region is almost consistent, the number of cracks reduces gradually, crack spacing becomes more unequal, bending stiffness and yield strength greatly reduce, ultimate flexural capacity and energy absorption capacity deteriorates, numerical simulation results are in good agreement with experiment.

scholarly journals Influence of prestress level on NSM CFRP laminates for the flexural strengthening of RC beams

2014 ◽  
Vol 116 ◽  
pp. 489-500 ◽  
Author(s):  
Mohammadali Rezazadeh ◽  
Inês Costa ◽  
Joaquim Barros
Keyword(s):  
Rc Beams ◽  
Flexural Strengthening ◽  
Cfrp Laminates
Sign in / Sign up

Export Citation Format

Share Document