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Article
LOAD-DEFLECTION BEHAVIOR OF REINFORCED CONCRETE BEAMS STRENGTHENED WITH CFRP SHEETS
تصرف الهطول مع التحميل في العتبات الخرسانية المسلحة المقواة بألياف الكاربون

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Abstract

In this study experimental investigation of the deflection control of R.C. beams strengthened using continuous Carbon Fiber Reinforced Polymer (CFRP) sheets is carried out. The test results show that the strengthening with (CFRP) sheet has a significant effect on the load-deflection response by increasing beam stiffness especially beyond the precracking stage. By using (CFRP), the maximum deflection is decreased by (26.7%) in comparison with control beam. The effect of Span to depth ratio has also an important role in the control of deflection. The reduction of (Span/Depth) ratio from (20) to (15, 12.5 and 10) will reduce the maximum deflection by (21%, 30.3% and 41.6%) respectively. The test results show the load-deflection response has not been affected significantly by increasing the steel reinforcement ratio at the pre-cracking stage. However, this behavior is dramatically changed at the cracking stage, by increasing steel reinforcement ratio of (2×ρmin) and (ρmax) as compared with (ρmin), the maximum deflection is reduced by (13.5% and 29.2%) respectively. Also the load-deflection response is not affected by the grade of steel reinforcement at the cracking stage. After the cracking stage with the anticipation of large contribution of tension reinforcement, the beam reinforced with steel of yield stress equal to (460 MPa) shows a difference in deflection with the beam reinforced with steel of yield stress equal to (300 MPa), the increment in the ultimate deflection is (23.8 %). Keywords: Strengthening, Deflection, CFRP sheet, Concrete Beam, Span to Depth ratio.

في هذه الدراسة تم أجراء تحريات عملية للسيطرة على الهطول في العتبات الخرسانية المسلحة والمقواة بصفائح الكاربون. حيث بينت النتائج أن استخدام هذه الصفائح له تأثير كبير على هذا التصرف اذ أن الهطول الاقصى قد ازداد بمقدار (26,7 %) للعتبة المقواة بالكاربون مقارنة بعتبة السيطرة والتي لم يتم تقويتها. أما بالنسبة لتأثيرنسبة (طول العتبة/سمكها) فله تأثير مهم أيضاً في السيطرة على هطول العتبة, فعند تقليل هذه النسبة من (20) الى (15و 12,5 و10) فأن الهطول الاقصى يقل بمقدار (21%, 30,3% و 41,6%) على التوالي. وقد بينت النتائج أن تصرف الهطول مع الحمل المسلط للعتبات لا يتأثر بكمية الحديد المستخدم خلال مرحلة ما قبل تشقق الخرسانة ولكن هذا السلوك يتغير بصورة ملحوظة عند تشقق الخرسانة حيث كانت نسبة النقصان في الهطول الاقصى لكل من العتبتين اللتين تم تسليحهما بكمية حديد (2×ρmin و ρmax) بمقدار (13,5% و 29,2%) عل التوالي. أما بالنسبة لصنف حديد التسليح المستخدم فأن ليس له أي تأثير على تصرف الهطول مع الحمل المسلط خلال مرحلة ما قبل تشقق الخرسانة ولكن ما بعد هذه المرحلة وعند مشاركة حديد التسليح في تحمل اجهادات الشد فأن لنوعية الحديد تأثير كبير على مقدار هطول العتبة الخرسانية وكما بينت نتائج فحص العتبة التي أحتوت على حديد تسليح ذو أجهاد خضوع بمقدار (460) نت/ملم2 أن مقدار الهطول الأقصى يزداد بمقدار (23,8%) مقارنة مع العتبة التي أحتوت على حديد ذو أجهاد خضوع (300) نت/ملم2.


Article
STUDYING THE BEHAVIOR OF THE PILE CAP FOR SHEAR REINFORCEMENT WHICH IS SIMULATED AS A CONTINUOUS DEEP BEAM USING SELF COMPACTING CONCRETE

Author: Zuhair Abd Hacheem
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2017 Volume: 21 Issue: 5 Pages: 88-100
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

This paper is focused on the effect of shear reinforcement on the structural behavior of continuous reinforced concrete deep beams to employ the results on the piles caps works. Experimental study using self-compacting concrete with constant compressive strength nominally equals 60 MPa were frequently used with three groups of shear span-to-depth ratios 0.95, 1.08 and 1.25 to produce twelve continuous beams. Each group of shear span-to-depth ratios has one unreinforced beam against shear stresses and three shear reinforced beams; the first is consist of horizontal stirrups only, the second has vertical stirrups only while the third from combined with horizontal and vertical stirrups to act together against shear stresses. The results revealed that the configuration of the combined shear reinforcement (horizontal and vertical) is an effective factor on the behavior of the deep beam and when it is increased in one category the ultimate strength and the serviceability of specimen can be improved. The percentage of the obtained improvement for a specimen can be increased by decreasing its shear span-to-depth ratio.

تركز هذه الورقة البحثية على تأثير تسليح القص على السلوك الإنشائي للعتبات الخرسانية المسلحة العميقة المستمرة لغرض الاستفادة من النتائج في أعمال قبعات الركائز. وقد استخدمت الدراسة العملية الخرسانة ذاتية الرص ذات مقاومة انضغاط ثابتة المقدار وقيمتها الإسمية تساوي 60 ميكا باسكال وتم تكرارها في ثلاث مجموعات من نسب فضاء القص-إلى-العمق وهي 0.95، 1.08 و 1.25 لغرض إنتاج اثنى عشر عتبة مستمرة. كل مجموعة من نسب فضاء القص-إلى-العمق تتكون من عتبة غير مسلحة تجاه إجهادات القص وثلاث عتبات مسلحة تجاه القص؛ الأولى مزودة بأطواق أفقية فقط والثانية مزودة بأطواق عمودية فقط أما الثالثة فزودت بكلا الحلقات الأفقية والعمودية لتعمل سوية تجاه إجهادات القص.كشفت النتائج عن كون ترتيب تسليح القص بزيادة التسليح إلى خليط من الحلقات الأفقية والعمودية هو عامل مؤثر على سلوك العتبات العميقة كما ويمكن تحسين المقاومة القصوى وقابلية الخدمية للنموذج. أن نسبة التحسن المئوية المستحصلة لنموذج معين يمكن زيادتها بتقليل قيمة نسبة فضاء القص-إلى-العمق لذلك النموذج.


Article
Studying the Strength of the Pile Cap Concrete Simulated as a Continues Deep Beam using Self Compact Concrete

Author: Zouhear A. Hachem
Journal: DIYALA JOURNAL OF ENGINEERING SCIENCES مجلة ديالى للعلوم الهندسية ISSN: 19998716/26166909 Year: 2018 Volume: 11 Issue: 2 Pages: 42-48
Publisher: Diyala University جامعة ديالى

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Abstract

This paper is an experimental study to investigate the effect of concrete compressive strength on the structural behavior of continuous reinforced concrete deep beams to utilize the results on the piles caps works. Three nominal concrete compressive strengths 50, 60 and 70 MPa obtained by self-compacting concrete were frequently used with four groups of shear span-to-depth ratios 5.71, 1.25, 1.08 and 0.95 to produce twelve continuous beams; three of them are shallow and the rest are deep. The comparisons were designed to reveal the variation in the structural behaviors among the shallow and deep specimens from a side, and among the deep specimen from another side. The experimental program concentrated on the ultimate strength, load-deflection curve, cracking and failure mode of the specimens. The results revealed that the concrete compressive strength is an effective factor on the behavior of the deep beam and when its value increased the ultimate strength and the serviceability of specimen can be improved about 48% whilst the enhancement achieved in shallow beams about 9%. The percentage of the obtained improvement for a specimen can be increased by decreasing its shear span-to-depth ratio.


Article
Experimental Study of Hydraulic Jump in Adverse Stilling Basin at Smooth Bed

Authors: Ali sadik Abbas علي صادق عباس --- Haider Alwash حيدر علوش --- Ali Abdul Jabbar Mahmood
Journal: DIYALA JOURNAL OF ENGINEERING SCIENCES مجلة ديالى للعلوم الهندسية ISSN: 19998716/26166909 Year: 2018 Volume: 11 Issue: 3 Pages: 7-13
Publisher: Diyala University جامعة ديالى

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Abstract

The effect of changing in the bed slope of stilling basins produces changing in characteristics of the hydraulic jump such as sequent depth ratio, length of jump ratio, length of the roller and energy dissipation ratio, consequently the dimensions of stilling basin changed. In this study hydraulic jump investigated on smooth bed (without any appurtenances) for three adverse slopes (- 0.03, - 0.045, - 0.06) in addition to horizontal bed slope, the experiments were applied for the range of Froude number (Fr1) between 3.99 and 7.48. The results showed a reduction about10 % in sequent depth ratio, 22.1 % in length of jump ratio, 20.51 % in length of roller ratio and 13.87% in the energy dissipation ratio when the adverse slope (- 0.06) used instead of horizontal bed for the same Froude numbers. Empirical equations for the sequent depth ratio, length of roller ratio and the energy dissipation ratio were obtained from the experimental data.


Article
Shear Capacity of Rc Beams With Web Reinforcement- A New Approach

Authors: Kaiss F. Sarsam --- Nabil A. M. Al-Bayati
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2005 Volume: 24 Issue: 9 Pages: 1278-1290
Publisher: University of Technology الجامعة التكنولوجية


Article
EXPERIMENTAL STUDY OF SELF-COMPACTING REINFORCED CONTINUOUS DEEP BEAMS

Authors: Abdul_Qader Nihad Noori --- Adnan Falih Ali
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 1 Pages: 43-65
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Test results of twelve reinforced self-compacted concrete two-span deep beams casted by using self-compacting concrete are reported. The main variables studied were shear span-to-overall depth ratio (a/h), concrete strength (fʹc) and the amount of vertical shear reinforcement ratio (ρv). All specimens had the same dimensions and main flexural reinforcement. Tests pointed out that all beams failed in shear with diagonal splitting mode. It was found that shear span to overall depth ratio (a/h) effects the load carrying capacity of beams such that a decrease of 50 % in that ratio from 1 to 0.5, the cracking load (Pcr) and ultimate load (Pult) increase by average ratios of 29% and 25% respectively. The concrete compressive strength (fʹc) are also had a noticeable influence on the continuous deep beams behavior such that increasing (fʹc) to almost twice from (33.81 to 67.8) MPa led to an increase in the cracking load (Pcr) and ultimate load (Pult) by average ratios of 12.75% and 16.5% respectively. When (ρv) is increased by 80% from (0.25% to 0.45%) a better increase shear capacity of both NSCC & HSCC deep beam having (a/h) ratio of 1.0 (enhancement reached to18.56% and 23.1% respectively) as compared to the reference beams without shear reinforcement (ρv=0).S


Article
Prestressed Precast Hollow-Core Slabs with Different Shear Span to Effective Depth Ratio
البلاطات المجوفة مسبقة الصب والجهد مع نسب مختلفة لفضاء القص الى العمق الفعال

Author: Jasim Mahmood Mhalhal جاسم محمد مهلهل
Journal: Wasit Journal of Engineering Sciences مجلة واسط للعلوم الهندسية ISSN: 23056932 Year: 2017 Volume: 5 Issue: 2 Pages: 1-11
Publisher: Wassit University جامعة واسط

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Abstract

Four full scale precast prestressed hollow-core slabs were tested under the influence of four lines loading with various values of shear span to effective depth ratio (a/d) (1.5, 2, 3.5 and 5). The dimensions of the hollow-core slab were 2000 mm, 1200 mm and 150 mm (length, width and thickness, respectively). All slabs were cast with a high compressive strength concrete of approximately 79.5 MPa. Experimental test results showed four patterns of failure mode depending on the ratio of (a/d). They were flexural failure, flexure-shear failure and shear compression failure. In addition to combination failure between tension shear and anchorage failure, accompanied by sliding strand in concrete. The failure loads decreased about 19.6% as (a/d) increased by 233.3%. Finally, the highest first crack load, 110kN, was recorded for sample, HCS 1.5, having the lowest (a/d) ratio.

يتكون برنامج الاختبار التجريبي من أربع بلاطات مجوفة مسبقة الجهد والصب ، اختبرت تحت تأثير أربع خطوط تحميل ، مع قيم مختلفةلنسبة فضاء القص الى العمق الفعال ) a / d ) حيث كانت ) 1.5 ، 2 ، 3.5 و 5(. كانت ابعاد البلاطة المجوفة المسبقة الجهد 2000 ملم، 1200 ملم و150 ملم )الطول ، العرض والسمك، على التوالي ( . جميع البلاطات صبت بخرسانه ذات مقاومة انضغاط عالية بحدود 79.5 ميجا باسكال. أظهرتنتائج الاختبار التجريبي أربعة أنماط من الفشل تبع ا لتنوع قيم نسب ) a / d ) ، وهي فشل الانثناء، فشل الانثناء القص ، وفشل ضغط القص بالإضافة -إلى فشل جمع بين فشل قص الشد والتثبيت يرافقه انزلاق حديد التسليح في الخرسانة . انخفضت أحمال الفشل بنسبة 19.6 ٪ عندما ارتفعت نسبة ) a / d )الى 233.3 ٪. وأخيرا، تم تسجيل أعلى حمولة للتشقق الأولى، 110 كيلو نيوتن ، للعينة HCS1.5 ، ذات أدنى نسبة ) a / d .

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