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Article
Flexural Strength and Ductility of CFRP Strengthened Reinforced Concrete Beams

Authors: Bayan S. Al-Numan --- . Jamal A. Farhan --- Othman K. Ali
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 7 Part (A) Engineering Pages: 1294-1307
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

A total of fourteen beams, 100×150 mm in cross-section were tested in the laboratory over an effective span of 2000 mm. Two of them were used as reference beams. Twelve fiber reinforced concrete beams were provided with externally bonded CFRP laminates at the soffit of the beam. The variables considered included number of CFRP layers, yield strength of steel reinforcement (fy) and steel reinforcement ratio (). All the beams were tested until failure. The test results showed that the ultimate load carrying capacity increased by 56% as average by increasing of the ratio of steel reinforcement from (0.0127 to 0.0324). The deflection ductility index DDI values averaged (1.80) and (1.75) for one-layer strengthened beams and two-layer ones, respectively. The corresponding energy ductility index EDI values averaged (1.75) and (1.73), respectively. The DDI and EDI for the control beams were 4.61 and 6.24, respectively. With the exception of the control beams, all of the beams exhibited poor ductility. Failures in all strengthened beams were accompanied by the release of large amounts of energy (known as elastic energy) relative to inelastic energy. Therefore, a reasonable factor of safety should be used in the design of FRP strengthened reinforced concrete members.


Article
Experimental and Numerical Study of the Effects Of Creating Openings in Existing RC Beams and StrengtheningWith CFRP
الدراسة التجریبیة والعددیة لتأثیرات عِمل فتحات يف الروافد الخرسانیة المسلحةوتقَو یّتھا بالالیاف الكاربونیة

Author: Hayder Qais Majeed
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2012 Volume: 30 Issue: 15 Pages: 2550-2561
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This study presents an experimental and nonlinear finite element analysis of creating square openings in existing RC beams and strengthening with CFRP laminate. Flexural strengthening of reinforced concrete beams is now becoming more and more important in the field of structural maintenance and retrofitting. In the experimental programming, three RC beams were cast. Two beams were tested in the un-strengthened condition the first act as the solid Control beam, and the other have openings, the third one have opening and strengthening with CFRP laminate. The beams were also modeled using a FEM packaged (ANSYS 11). The results indicate that the strengthened beam recorded the highest failure load and its mode of failure was ductile. The numerical results seemed to be able to predict the behavior of the beams.

ُيقومُ هذا البحث بالدراسةِ المختبرية وايضا بأستعمال التحليل اللاخطّيَ للعناصرَ المحددَة للتأثيراتَ الناتجة عن عمل فتحات مستطيلةِ في الروافد الخرسانية المسلحة بالأضافة الى دراسة تقويتها بالالياف الكاربونية.ان تَقْوِية الروافد الخرسانية المسلحِة أُصبحُ في الوقت الحاضرأكثر أهمية في حقلِ الصيانةِ الهيكليةِ والترميم.في الدراسة المختبرية, تم عمل ثلاثة نماذج من الروافد الخرسانية المسلحةْ. النموذج الاول عبارة عن رافدة بدون فتحات تعمل كعتبة سيطرة, اما النموذجين الاخريين فقد تم عمل فتحات عند منطقة القص ، احد هذين النموذجين مقوى بالالياف الكاربونية. كما تم نمذجة الروافد أيضا بأستعمال التحليل اللاخطّيَ للعناصرَ المحددَة وذلك بواسطة برنامج الانسز (ANSYS 11). تُشيرُ النَتائِجُ بأنّ الرافدة المُقَوّاةَ سجلت أعلى حمل فشلِ من نظيراتها بدون تقوية ونمطِها في الفشلِ يكون أكثر مرونة. كما بينتْ النَتائِجُ بان الدراسة العدديةُ قادرة على تَوَقُّع سلوكِ الروافد كما انها تعطي نتائج مقاربة للدراسة المختبرية.


Article
Effect of CFRP Layer Orientation on the Behavior of Shear-Strengthened Steel Plate Girders

Authors: Mohammed J. Hamood --- Wael Sh. Abdulsahib --- Ali H. Abdullah
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 7 Part (A) Engineering Pages: 709-714
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The present paper investigates experimentally the impacts of fiber layer orientation on the structural behavior of CFRP strengthened steel-plated girders that are subjected to shear. Three of these girders were considered strengthened girders whereas the last one represents the reference girder. Each of the four steel-plated girders was tested aside and in different periods of time using the shear buckling test. A point load was applied to the center of the top flange of the four girders using Avery hydraulic machine. A laminated carbon fiber reinforced polymer sheet (CFRP) was fully adhesively attached to the web area of the three girders. The attached carbon fiber sheet took different patterns: either on one side or on both sides. Such a step helps to evaluate the most effective strengthening technique of each of the girders using CFRP composite. To check the behavior and the increase in the ultimate shear capacity of the girders, several parameters were examined. Results have revealed that both the unstrengthen and strengthened girders of different orientations of CFRP showed a similar stiffness behavior at a relatively low load levels. However, when the load is increased, the stiffness behavior significantly is increased in the three strengthened girders, compared to the strengthened girders. It has further shown that the ultimate shear load of the three strengthened girders were higher than that of the reference girder. Such a result can clearly be exemplified by the obtained ranges: 19.56% and 25% depending on the orientation of the CFRP laminates. Following Von Mises stresses, the researcher was able to predict the ultimate shear load of the four girders and to figure out the arrived at results from the four experimental tests.


Article
Structural Behavior of HS-SC Reinforced Concrete Beams with Longitudinal and Transverse Openings Strengthened with CFRP Laminates
السلوك الإنشائي للعتبات الخرسانية المسلحة عالية المقاومة ذاتية الرص ذات الفتحات الطولية والجانبية المقواة بصفائح ألياف الكربون بالبوليمرية

Authors: Hussain Dhafer AbdulJabbar --- Yaarub Gatia Abtan
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 5 Pages: 48-67
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Service runs had produced several shortcomings when congested in one place. So, using longitudinal and transverse opening in beams (BLTO) was creative solution for the purpose of serve those runs with other benefits, especially when utilized high strength self-compacting concrete (HS-SCC). To control cracks in web opening regions which lead to possible leakage, carbon fiber reinforced polymer (CFRP) laminates was significant strengthening system to realize that purpose. This study examined the behavior of thirteen reinforced concrete (RC) beams. These beams were involved into three groups. All beams were identical in dimensions, reinforcement, concrete type, and hole dimensions. The evaluation is used to elect the optimum hollow core section, position effect of web openings with fixed hollow core section, and effect of strengthened web openings. Due to recorded load capacity, a reduction was produced by hollow core position at mid and bottom section by about (2%-14%), respectively, with comparing by solid section. Therefore, the optimum hollow core section was when it locate in mid beam section which used to unify BLTO sections. BLTO types indicated different loading data according to web opening position. The decrement of opening provision was about (20.4%) by compared with hollow beam (without web-opening) and about (22%) by compared with solid beam. The optimum BLTO is when the web opening located in mid-shear zone, while the critical one recorded in web opening position in mid-span and near supports in same BLTO. Presence of CFRP system in same BLTO copy had enhanced beam resistance by about (29%) and prevents cracks to reach in web opening or with minimum hairline cracks without delaminating problem. The registered failure mode of all beams was contained two main type, suddenly flexural failure in compressive zone by concrete cover crushing and flexural-shear failure. Additionally, local failure occurred at central CFRP strips by ripping-off concrete cover through the edges of it.

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