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.

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.

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.

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.

Experiment on Flexural Capacity of Damaged RC Beams Strengthened with Composite CFRP

2014 ◽  
Vol 501-504 ◽  
pp. 932-935
Author(s):  
Tao Luo
Keyword(s):  
Bearing Capacity ◽  
Ultimate Bearing Capacity ◽  
Experimental Results ◽  
Rc Beam ◽  
Rc Beams ◽  
Reinforcement Effect ◽  
Flexural Capacity ◽  
Loading Test ◽  
Research Results ◽  
Cfrp Sheets

In order to study the flexural capacity of the seismic damaged RC beams after reinforcement, the bearing capacity and ductility are comprehensively evaluated, which is based on the results of three points of division loading test on 8 models which are divided into 4 groups. Experimental results show that compared with the direct pasting CFRP, the ultimate bearing capacity of RC beam strengthened by composite CFRP sheets is much higher, the average is 20.7%. Cracking load and ductility are also improved higher. The reinforcement effect of CFRP sheets is used very well. The research results provide advice and reference for the next seismic damaged RC beams in the reinforcement engineering.

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.

Experimental Study on Precracked RC Beams Strengthened with Externally Bonded CFRP Sheets

2010 ◽  
Vol 150-151 ◽  
pp. 842-846 ◽  
Author(s):  
Jiang Feng Dong ◽  
Qing Yuan Wang ◽  
Yan Mei Zhu
Keyword(s):  
Reinforced Concrete ◽  
Research Work ◽  
Concrete Cover ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Control Beam ◽  
Cfrp Sheets ◽  
Modes Of Failure

This paper presents the results of an experimental research work designed to study the flexural strengthening capacity and the modes of failure of Reinforced Concrete (RC) rectangular beams which are strengthened with external bonding of carbon fiber reinforced polymer (CFRP) composite materials to the tensile face of the RC beams. In total, seven beams were cast, one beam was preserved as control beam, two beams were strengthened without the application of preloading and the four beams were precracked and repaired with CFRP sheets. The main experimental parameters include the original damaged degree of RC beams, the amount of CFRP sheets, the longitudinal tensile reinforcement ratio, shear span to effective depth ratio, and the concrete cover thickness. All beams were tested in four-point bending over a span of 1500mm. Test results in the current study indicate that the effectiveness and flexural capacity of the CFRP strengthened beams. The flexure enhancement of the CFRP strengthened beams varied between 41% and 125% over the control beam. This study confirms that the CFRP sheets technique significantly enhances the flexural capacity of reinforced concrete beams. Finally, the contribution of CFRP sheets on the flexural capacity and rigidity of precracked and non-precracked RC beams is significant for the more longitudinal tensile reinforcement ratio.

Comparison of flexural capacity of different hollow slab beams with/without pavement layer reinforced by steel plates

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Long Liu ◽  
Lifeng Wang ◽  
Ziwang Xiao
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Steel Plate ◽  
Plate Thickness ◽  
Experimental Results ◽  
Nonlinear Material ◽  
Finite Element Models ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Content Type

PurposeReinforcement of reinforced concrete (RC) beams in-service have always been an important research field, anchoring steel plate in the bottom of the beams is a kind of common reinforcement methods. In actual engineering, the contribution of pavement layer to the bearing capacity of RC beams is often ignored, which underestimates the bearing capacity and stiffness of RC beams to a certain extent. The purpose of this paper is to study the effect of pavement layer on the RC beams before and after reinforcement.Design/methodology/approachFirst, static load experiments are carried out on three in-service RC hollow slab beams, meanwhile, nonlinear finite element models are built to study the bearing capacity of them. The nonlinear material and shear slip effect of studs are considered in the models. Second, the finite element models are verified, and the numerical simulation results are in good agreement with the experimental results. Last, the finite element models are adopted to carry out the research on the influence of different steel plate thicknesses on the flexural bearing capacity and ductility.FindingsThe experimental results showed that pavement layers increase the flexural capacity of hollow slab beams by 16.7%, and contribute to increasing stiffness. Ductility ratio of SPRCB3 and PRCB2 was 30% and 24% lower than that of RCB1, respectively. The results showed that when the steel plate thickness was 1 mm–6 mm, the bearing capacity of the hollow slab beam increased gradually from 2158.0 kN.m to 2656.6 kN.m. As the steel plate thickness continuously increased to 8 mm, the ultimate bearing capacity increased to 2681.0 kN.m. The increased thickness did not cause difference to the bearing capacity, because of concrete crushing at the upper edge.Originality/valueIn this paper, based on the experimental study, the bearing capacity of hollow beam strengthened by steel plate with different thickness is extrapolated by finite element simulation, and its influence on ductility is discussed. This method not only guarantees the accuracy of the bearing capacity evaluation, but also does not require a large number of samples, and has certain economy. The research results provide a basis for the reinforcement design of similar bridges.

Protection of railway infrastructure objects against electrical corrosion

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liudmyla Trykoz ◽  
Svetlana Kamchatnaya ◽  
Dmytro Borodin ◽  
Armen Atynian ◽  
Roman Tkachenko
Keyword(s):  
Leakage Current ◽  
Electrical Resistance ◽  
Electrical Current ◽  
Leakage Currents ◽  
Destructive Effect ◽  
Accelerated Corrosion ◽  
Content Type ◽  
Pedestrian Bridges ◽  
Railway Infrastructure ◽  
Bridge Structures

Purpose The purpose of this paper is to develop a technological method of protection against electrical corrosion. One more way to protect the objects is to prevent the electrical current from getting to them. For example, railway objects are surrounded with a material with raised electrical resistance. Design/methodology/approach The railway infrastructure objects (foundations, contact-line supports, reinforced concrete sub-bases, bridge structures, pipelines of engineering networks, supports of passenger platforms and pedestrian bridges, concrete plinth walls of station buildings) are subjected to destruction due to the action of electrical current. One of destruction factors is a corrosion of the concrete constructions which is caused by the leakage current action. Findings Leakage currents and stray currents bypass the structure of supports of high passenger platforms or pipes of engineering networks. These currents spread by the line with the least resistance outside of the structures. Research limitations/implications Electrical leakage current from the rails gets into such structures through sleepers, ballast and soil and leads to accelerated corrosion leaching of concrete. Practical implications The constructions are protected against the destructive effect of electrical corrosion on the metal or concrete of the structure. This scheme is suitable for the construction and reconstruction of railway structures which operate on electrified sections of railways. Originality/value Schemes of technological solution are proposed for protection of foundations, supports of high passenger platforms, pipelines of engineering networks, etc. For this, the arrangement of soil-contained screens with big electrical resistance is suggested.

Construction Technology Research of RC Beams Strengthened with Prestressed CFRP Plates

2011 ◽  
Vol 268-270 ◽  
pp. 659-663
Author(s):  
Hua Chen ◽  
Kan Kang ◽  
Lang Ni Deng
Keyword(s):  
Crack Resistance ◽  
Concrete Beams ◽  
High Strength ◽  
The Self ◽  
Bending Test ◽  
Construction Technology ◽  
Rc Beams ◽  
Test Results ◽  
Technology Research ◽  
Flexural Capacity

The method of applying prestress to CFRP plates can make full use of the characteristics of high-strength, enhance the force properties, prevent peeling damage and reduce the strain lag. Construction technology of prestressed CFRP plates strengthening reinforcement concrete beams was introduce in this paper, and bending test of 6 reinforcement concrete beams strengthened with prestressed CFRP plates were carried out based on the self-developed prestressed CFRP plates supporting anchorages. The test results indicate that the flexural capacity and crack resistance capacity can be increased compared with non-prestressed CFRP plates, and the construction technology can be adopted in practical projects.

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