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Article
Embedded Length Of Steel Bars In Self Compacted Concrete (SCC)

Authors: Ali I. Salahaldin --- Amer F. Izzat
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2011 Volume: 17 Issue: 5 Pages: 1077-1089
Publisher: Baghdad University جامعة بغداد

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Abstract

Experimental research was carried out on eight reinforced concrete beams to study the embedded length of the longitudinal reinforcement. Six beams were casted using self compacted concrete, and the two other beams were casted using normal concrete. The test was carried out on beams subjected to two point loads. The strain and the slip of the main reinforcement have been measured by using grooves placed during casting the beams at certain places. The measured strain used to calculate the longitudinal stresses (bond stress) surrounding the bar reinforcement, The study was investigated the using of self compacted concrete SCC on the embedded length of reinforcing bars, and comparing the results with normal concrete.The test results show that using SCC improve the concrete properties like the compressive strength and the tensile strength which mainly affected the bond strength and the splitting of the concrete cover failure. The testes show that with increasing concrete strength the bond strength increased.

دراسة عملية اجريت على ثمان عتبات خرسانية مسلحة لدراسة طول الطمر لقضبان حديد التسليح الموضوع في الخرسانة.ست نماذج استخدمت فيها الخرسانة ذاتية الرص ونموذجان استخدم فيهما خرسانة اعتيادية. الفحوصات اجريت على عتبات حملت بنقطتي تحميل. وباستخدام فراغات معينة وضعت في اثناء الصب داخل النماذج لقياس الانفعالات في قضبان حديد التسليح وكذلك لقياس الانزلاق الذي من الممكن ان يحدث, تم قياس اجهاد القص المحيط بقضبان حديد التسليح والمسبب للفشل وانسحاب قضبان حديد التسليح. الدراسة ركزت على عاملين رئيسيين هما:-قوة تحمل الخرسانة.-وطول الطمر المتاح لقضبان حديد التسليح.لايجاد كيفية تاثيرهما على قيم اطوال الطمر في حالة استخدام خرسانة ذاتية الرص. وكذلك مقارنة النتائج مع الخرسانة الاعتيادية. اظهرت النتائج تحسن في خواص الخرسانة في حالة استخدام الخرسانة ذاتية الرص من ناحية مقاومة الانضغاط ومقاومة الشد الذي يؤثر تاثير مباشر على مقاومة الترابط وفشل الغطاء الخرساني وتهشمه


Article
The Effective Embedded Length of Steel Bars in Self Compacted Concrete (SCC)

Authors: Ali I. Salahaldin --- Amer F. Izzat
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2011 Volume: 17 Issue: 3 Pages: 594-609
Publisher: Baghdad University جامعة بغداد

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Abstract

Eight reinforced concrete beams were tested in order to investigate the effective embedded length of the longitudinal reinforcement bar in self compacted concrete (SCC). All specimens were reinforced with a uni-reinforced bar, six of them embedded in self compacted concrete and the others embedded in normal concrete. The test was carried out on simply supported beams loaded at two points. At the end of the reinforcement bar slip was measured, also under the loading point slip and the bar strain were measured. The investigated variables in this study were: The bar diameter, and the available embedded length.To find out how these variables influence the embedded length in case of using self compacted concrete and comparing it with the normal concrete. The results show that, with increasing the bar diameter, bond stress slightly decreases, while with increasing the embedded length of the longitudinal bar the bond stress decreases and this improves the mode of the bond failure, especially for the specimens having small bar diameter

دراسة عملية اجريت على ثمان عتبات خرسانية مسلحة لدراسة الطول المطمور لقضبان حديد التسليح الموضوع في الخرسانة ذاتية الرص . كل التماذج تحتوي على قضيب تسليح احادي . ست منها استعملت فيها خرسانة ذاتية الرص ونموذجين استعمل فيها الخرسانة الاعتيادية. الفحوصات اجريت على عتبات بسيطة الاسناد, حملت بنقطتي تحميل. في نهاية حديد التسليح تم قياس الانسحاب , واسفل نقطة التحميل تم قياس الانسحاب لحديد التسليح مع الانفعال الحاصل في حديد التسليح.تم بحث المتغيرات التالية في هذه الدراسة: قطر قضيب حديد التسليح. وطول التثبيت المتاح لقضبان التسليح.لايجاد كيفية تاثيرهما على قيم الطول المطمور في حالة استخدام خرسانة ذاتية الرص ومقارنتها بالخرسانة الاعتيادية.اظهرت النتائج المختبرية بانه مع ازدياد قطر حديد التسليح يقل اجهاد الترابط بمقدار طفيف. ومع ازدياد الطول المطمور يقل اجهاد الترابط وهذا يحسن من نوع فشل الترابط الحاصل, وخصوصا في النماذج الحاوية على تسليح قليل.


Article
Effect of Shear Span-Depth Ratio on Shear Strength of Porcelanite Lightweight Aggregate Reinforced Concrete Deep Beams Strengthened by Externally Bonded CFRP Strips

Authors: K.F. Sarsam --- N.A.M. Al-Bayati --- A.S. Mohammed
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2017 Volume: 35 Issue: 3 Part (A) Engineering Pages: 267-275
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This paper presents an experimental investigation of structural behaviour of reinforced concrete deep beams strengthened in shear by CFRP strips. The experimental program consisted of fabricating, casting and testing of nine identical porcelainte lightweight aggregate reinforced concrete deep beams. Three of the tested deep beams were unstrenghtened to serve as reference beams, while the remaining beams were tested after being strengthened using CFRP strips in two different orientations (vertical and horizontal). The locally available natural porcelanite aggregate is used to produce lightweight aggregate concrete. The beams were designed to satisfy the requirements of ACI 318M- 14 building code. In order to insure shear failure modes, adequate flexural steel reinforcement were provided. Effect of three different values of shear span to effective depth ratio (a/d =1.0, 0.8, 1.2) were selected. All beams have been tested as a simply supported beams subjected to two concentrated points loading. The beam specimens were tested up to failure under monotonic loads. The experimental work showed that the failure load increases as the shear span to effective depth ratio deceases. As the shear span to effective depth ratio decreased from 1.0 to 0.8, the percentage of increase in the ultimate load was about 24%. In addition, the diagonal compression strut crack of unstrenghtened control beams was changed to several diagonal cracks at mid depth within the shear span of the strengthened beams and exhibited more ductile failure mode.


Article
EFFECT OF WEB OPENING'S SHAPE ON THE BEHAVIOR OF HYBRID REINFORCED CONCRETE DEEP BEAMS UNDER REPEATED LOADING

Authors: Sawsan Akram Hassan --- Mohammed Kamil Ali
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 3 Pages: 128-141
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

This research aims to study experimentally behavior of hybrid deep beams with web openings when subjected to two points' monotonic and repeated loading in effect of web openings shape. All tested deep beams have the same flexural (0.0184) and web reinforcement (ρw=0.003) and same dimensions of (1500mm length, 150mm width and 350mm height). In this research, the idea of hybridity was achieved by reinforcing the two shear spans with steel fiber keeping the middle span free from this fiber. The aim was to strengthen shear region against shear failure (diagonal strut failure). To achieve the aim, six deep beams were cast and tested. Three of them were tested under monotonic loading as control beams to the other three beams tested under repeated loading at levels of 55% of the ultimate load of their control beams. The variables studied were: loading type (either monotonic or repeated) and web opening shapes. The results indicated that using different opening shapes (rectangular, circular or square) with an equivalent shape of 1.37% of beam size show that the ultimate load of beams with rectangular opening decreases by 10% as compared with beams with square web openings of the same area. Also, the ultimate load of beams with circular openings increases by 6.8% as compared with beams with square web openings of the same area. Also, it can be concluded that deep beams haves circular openings are increasing in ultimate loads by 17.5% as compared to rectangular web openings shapes with equivalent area.


Article
BEHAVIOR OF HYBRID REINFORCED CONCRETE DEEP BEAMS WITH WEB OPENINGS UNDER REPEATED LOADING

Authors: Sawsan Akram Hassan --- Mohammed Kamil Ali
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 4 Pages: 52-75
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

This research aims to study experimentally behavior of hybrid deep beams when subjected to two point's monotonic and repeated loading in presence or absence of web openings. All tested deep beams have the same reinforcement in flexural (ρ= 0.0184) and web (ρw=0.003) and same dimensions of (1500mm length, 150mm width and 350 mm height). In this research, the idea of hybridity was achieved by reinforcing the two shear spans with steel fiber keeping the middle span free from this fiber. The aim was to strengthen shear wings against shear failure (diagonal strut failure). To achieve the aim, twelve deep beams were cast and tested. Six of them were tested under monotonic loading as control beams to the other six beams tested under repeated loading at levels of 55% of the ultimate load of their control beams. The variables attempts were: loading type (either monotonic or repeated), beam type (either hybrid or non-hybrid), steel fiber (SF) ratio, and finally web opening sizes. The results illustrate that the ultimate load of deep beam with web openings under monotonic loading increases as the SF ratio increases. When SF was added to shear spans with a ratios of 1% and 2% under monotonic loading system, the ultimate load percentages increase are 37.5% and 68.75%, respectively compared with ultimate loads of beams which are without SF. Also, using fiberous concrete in casting the entire length of beams leads to an increase in the ultimate load of 4.55% as compared with deeps beams with the same SF ratio of 1%, and 43.75% as compared with beams cast with conventional concrete. The results using different opening size of square shapes, it was found that the ultimate load decrease as size of web openings increases from 0.61% of beam size to 1.37% of beam size by 10.17% and 25.42%, respectively as compared with hybrid deep beam without openings.


Article
Effect of CFRP Strips Orientation on Performance of Strengthened Deep Beams

Author: Ahmed Sagban Saadoon
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2019 Volume: 12 Issue: 3 Pages: 172-177
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

This study was carried out in order to explore the behaviour of RC deep beams strengthening with CFRP strips. Eight simply supported deep beams were fabricated and tested under four-points loading scenario. Three different orientations for CFRP strips were used for strengthening the RC deep beams ; vertical, horizontal and inclined. All of the tested samples were of the same dimensions, concrete strength and steel reinforcement. A percentage increase in load carrying capacity of 48, 19 and 38% (with respect to the unstrengthened beam) was gained for beams strengthened with vertical, horizontal and inclined FRP strips, respectively. It was concluded that the strengthening with FRP strips of vertical fabric orientation is more efficient than strengthening with horizontal or inclined orientation since the vertical orientation gives the highest load carrying capacity, largest deflections at ultimate load and smallest crack width. On the other hand, applied the FRP strips in a horizontal orientation was insufficient for the strengthening purposes.


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 .


Article
ExperimentalandNumericalInvestigation of Self Compacting Reinforced Concrete Dapped End BeamsStrengthened with CFRP Sheets

Authors: Qasim Mohammed --- ShakirBaneen Basim Abd --- Ali Talib Jasim
Journal: Journal of University of Babylon مجلة جامعة بابل ISSN: 19920652 23128135 Year: 2018 Volume: 26 Issue: 7 Pages: 16-35
Publisher: Babylon University جامعة بابل

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Abstract

This study aims to investigate experimentally the behavior of self-compacting reinforced concrete dapped end beams strengthened with CFRP sheets and, then theoretically by ANSYS 15.0 software. The experimental program consists of testing 14-specimens each of dimensions (200x400x1500 mm) with two values of Shear span to depth effective(a/d), namely (1.5 and 1.0).Two of the beams are a control beams (with full reinforcement), and four beams with reduced reinforcement in hanger and nib regions.The other beams have been strengthened with several configurations by CFRP sheets for the same values of (a/d),the comparison between results included load-deflection curves and cracked specimens. It was found that the strut and tie model (STM) is very conservative somehow,reduction the nib reinforcements by about (60%), in reduction in failure load by about (35% and 15%) for the two values of (a/d). With respect to the strengthened specimens, it observed that the strengthening with inclined CFRP strips (450) yielded better results in comparison with other configurations.The improvement in load capacity was about (23%) for (a/d=1.5 and 1.0). Also, it is found that the nonlinear model adopted in the present work compered the experimental testsyielded a good agreement with difference of about (12%).

الهدف منهذهالدراسةهو التحري عمليا عن سلوك الاعتاب الخرسانية الذاتية الرص ذات النهايات المستدقة المقواةبشرائحالياف الكاربون البوليمرية،ثمنظريابواسطةبرنامجANSYS.يتكونالبرنامجمناختبار 14 عينةذاتأبعاد (200 × 400 × 1500 ملم) معقيمتينمن (a/d) وهي (1.5 و1.0). وكانت اثنتين منالاعتاب مرجعية (بتسليح كامل) كما تم تقوية الاعتاب الأخرى في مناطق((Hanger& Nibبعدة تشكيلات بشرائح الكاربون البوليمرية لنفس القيم من (a/d)،وشملتالمقارنةبينالنتائجمنحنياتالتحمل والهطول. وقدوجدأنطريقةSTMمتحفظةجدابطريقةما،وان تقليل حديدNibبنحو (60٪)،قلل منحملالفشلبحوالي (35٪ و15٪) للقيمتين (a /d). فيمايتعلقبالعيناتالمقواة،لوحظأنالتقويةبشرائحالياف الكاربون البوليمرية المائلة بزاوية (450) أسفرتعننتائجأفضلبالمقارنةمعاالتشكيلاتالأخرى. كانالتحسنفيسعة التحميل حوالي (23٪) لـ (a/d=1.5 , 1.0). كذلكوجدأنالتحليلاللاخطيالمعتمدفيهذاالعمل مقارنة مع فحوصات العملي أسفرعنتوافقجيدمعفرقيبلغحوالي (12٪).

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