scholarly journals SHEAR CAPACITY PREDICTION FOR STIRRUP-CORRODED RC BEAMS STRENGTHENED WITH FRP

2019 ◽  
Vol 11 (1) ◽  
pp. 32-39 ◽  
Author(s):  
Ahmed K. El-Sayed
Keyword(s):  
Shear Capacity ◽  
Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Accelerated Corrosion ◽  
Rc Structures ◽  
Cfrp Sheets ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Shear Reinforcements ◽  
Corrosion Of Steel

Corrosion of steel reinforcement represents one of the main causes of deterioration and degradation of reinforced concrete (RC) structures. Shear reinforcements (stirrups) as an outer reinforcement in RC beams are more susceptible to corrosion problems and damage. This paper describes an analytical procedure for predicting the shear capacity of stirrup-corroded RC beams strengthened in shear using FRP laminates. The procedure shows how to incorporate the effects of the damages due to corrosion of stirrups into the design equations. An experimental investigation has been conducted to provide experimental data on the shear capacity of RC beams with corrosion-damaged stirrups strengthened using carbon fiber reinforced polymer (CFRP) sheets. The experimental study comprised three beams of 200 mm wide, 350 mm deep, and 2800 mm long. The steel stirrups in the beams were corroded using an accelerated corrosion technique. After CFRP strengthening, the beams were tested in four-point bending under a simply supported span of 2400 mm. The shear capacity of the strengthened beams was predicted using the proposed procedure and compared with the experimental ones. Good correlations were found between the predicted and experimental shear strength of the beams.

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.  

REPAIR OF CORRODED RC BEAMS

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Nabil Al-Akhras ◽  
Walid Al-Kutti ◽  
Abdulaziz Aljaber
Keyword(s):  
Electrical Current ◽  
Rc Beams ◽  
Portland Cement Concrete ◽  
Flexural Capacity ◽  
Significant Deterioration ◽  
Accelerated Corrosion ◽  
Cfrp Sheets ◽  
Granulated Blast Furnace Slag ◽  
And Performance ◽  
Corrosion Of Steel

Twelve prototype rectangular RC beams (120 x 150 x 1000 mm) were constructed and evaluated using flexural test to investigate the employment of advanced composites in repairing corroded reinforced concrete (RC) beams. Three concrete mixtures with effective w/c ratio of 0.4 and cement content of 370 kg/m3 were utilized in the study: control ordinary Portland cement concrete, silica fume (SF) and ground granulated blast furnace slag (GGBFS) concrete mixes. The RC beams (reinforced with two steel bars having diameter of 12 mm) were immersed (after 28 days of curing) in 2.5% NaCl solution and exposed to accelerated corrosion process using impressed electrical current. The corroded RC beams were repaired using advanced composite of carbon fiber reinforced polymer (CFRP) sheets. The CFRP sheets measuring 300-mm width by 0.131-mm thickness were used to rehabilitate and restore the mechanical behavior of the corroded and damaged RC beams. The investigation results confirmed that the corrosion of steel reinforcement caused significant deterioration and reduction of flexural capacity. The corroded SF and GGBFS beams showed higher flexural capacity compared to the corroded OPC beams. The repaired SF and GGBFS beams showed higher ductility and performance gain in the flexural capacity compared to the repaired OPC beams.

Fatigue Performance of Corroded RC Beams Strengthened with CFRP Sheets

2011 ◽  
Vol 243-249 ◽  
pp. 5589-5594
Author(s):  
Li Song ◽  
Zhi Wu Yu
Keyword(s):  
Fatigue Behavior ◽  
Effective Cross Section ◽  
Fatigue Performance ◽  
Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Cross Section Area ◽  
Section Area ◽  
Steel Bars

The paper presents the results of an experimental study on fatigue performance of corroded reinforced concrete (RC) beams repaired with carbon fiber reinforced polymer (CFRP) sheets. Five beams were constructed. One specimen was strengthened and not corroded; another four specimens were corroded and was strengthened with CFRP sheets. Five specimens were tested in fatigue. The results showed that steel bars corrosion reduced the fatigue life significantly while the CFRP strengthening enhanced the fatigue performance significantly. The effects of reinforcement corrosion on fatigue behavior of the strengthening beam can be attributed to a combination of four factors, including deteriorated bond behavior between reinforcement bras and surrounding concrete, loss of effective cross-section area of reinforcement, the stress concentration on steel bars, and degradation of mechanical properties of steel bars.

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.

Flexural experimental study on reinforced concrete beams strengthened with carbon fiber-reinforced polymer laminates using anchorage systems

2019 ◽  
Vol 9 (8) ◽  
pp. 923-930
Author(s):  
Ning Zhuang ◽  
Junzhou Chen ◽  
Miao Zheng ◽  
Da Chen
Keyword(s):  
Carbon Fiber ◽  
Fiber Reinforced Polymer ◽  
Bending Test ◽  
Carbon Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Flexural Capacity ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

Flexural capacity of RC beams gets significant improvement with externally bonded Carbon Fiber-reinforced Polymer (CFRP) sheet. The anchorage system is a valid means to restrain or delay debonding failure caused by stress concentration at the ends of CFRP sheets. In this paper, four RC beams, measuring 150 × 200 × 1900 mm, were examined under four-point bending test. One beam was applied for contrast. And other three were CFRP strengthened with no anchorage, CF anchors (carbon fiber anchors) and U-wraps (U-shaped CFRP wraps). The primary purpose of the experiment was to validate the effectiveness of CF anchors and U-wraps in improving the flexure character of beams strengthened with CFRP sheets. The experimental results revealed that the strengthened beams using anchorage systems performed remarkably in beam ductility, flexural capacity, load-deflection response and failure mode compared with the contrast beam. The anchorage systems were more effective and necessary to enhance the flexural behavior of beams as using CFRP laminates for flexural strengthening.

Calculation of Shear Capacity of Steel and Concrete Composite Beams Strengthened with FRP

2012 ◽  
Vol 166-169 ◽  
pp. 3290-3293
Author(s):  
Jiong Feng Liang ◽  
Ze Ping Yang ◽  
Jian Bao Wang ◽  
Jian Ping Li
Keyword(s):  
Experimental Data ◽  
Composite Beams ◽  
Shear Capacity ◽  
Fiber Reinforced Polymer ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Reinforced Polymer

Some calculated methods of shear capacity of RC beams strengthened with FRP (fiber reinforced polymer) are reviewed based on the experimental data on shear capacity of RC beams strengthened with FRP. Therefore, according to the destruction forms of steel and concrete composite beams strengthened with FRP, the formula for calculating the shear capacity of the beams are given. The formula is expressed clearly, simple and easy to use.

Optimum Design of Carbon Fiber-Reinforced Polymer for Increasing Shear Capacity of Beams

2020 ◽  
pp. 183-194
Keyword(s):  
Carbon Fiber ◽  
Optimum Design ◽  
Shear Capacity ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Rc Structures ◽  
Reinforced Polymer ◽  
Externally Bonded ◽  
Carbon Fiber Reinforced

For reinforced concrete (RC) structures, retrofit of structures are needed to be done for several situations. These situations include the renovation of structure by adding new components (floors or extension) and elimination of safety risks (resulting from unforeseen effects - forces and durability). Most retrofit methods for RC structures need destruction of existing members and hard work on increasing of existing section dimension and reinforcements. Whereas, using carbon fiber reinforced polymer (CFRP) strips is an easy option to increase the flexural moment or shear capacity of RC members without destruction. In that case, the use of the structure is provided during the application. In this chapter, the optimum design of CFRP strips is presented for increasing the insufficient shear capacity of RC beams. The design constraints are provided according to ACI-318: Building code requirements for structural concrete and ACI-440: Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structure.

Experimental Study on Shear Capacity of RC Beams Strengthened with Carbon Fiber Reinforced Polymer Mandated by ACli 440

2016 ◽  
Vol 845 ◽  
pp. 154-157
Author(s):  
Sri Tudjono ◽  
Himawan Indarto ◽  
Monica Devi
Keyword(s):  
Experimental Study ◽  
Carbon Fiber ◽  
Shear Capacity ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Rc Beam ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

Shear reinforcement for retrofitting an RC beam using unidirectional Carbon Fiber Reinforced Polymer (CFRP) woven can only be applied on the beam’s body below the concrete floor slab. Thus, it cannot fully curb like the way stirrups do, in which it will affect the shear capacity. The CFRP can only be ‘n’or ‘u’ shaped, taking into consideration the direction of shear force. Herein, the experimental study of the shear capacity ofshear capacity the beam strengthened by FRP is carried out.shear capacity The beams are RC beams of width 150 mm, height 300 mm, span of 1000 mm, f'c = 26 MPa having 2 bar of 19 mm diameter (fy = 403.65 MPa) and stirrups 6 mm diameter of 250 mm spacing (fy=375 MPa). The shear capacity measured is then compared with the shear capacity calculated using ACI 440. The result shows that the shear capacity measured from experiment is greater than the shear capacity calculated by ACI 440. Also, theshear capacity of RC beam with CFRP reinforcement n shape is greater than u shape.

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