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Article
Experimental Research on Tension Lap Splice in Reactive Powder Concrete Beams Exposed to Repeated Loading

Authors: Q.A-M. Hassan --- H.M. AlHassani --- F.F. Saleem
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2017 Volume: 35 Issue: 5 Part (A) Engineering Pages: 479-484
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This research is a part of an experimental study to examine the effect of lap splicing tension steel bars reactive powder concrete (RPC) beams under repeated loads. Eight RPCbeams whose tension steel bars were spliced at mid-span for a length equals 20 times the bar diameter and one RPC beam without lap splice were casted and tested. These beams were simply supported and tested up to failure under the action of two point repeated loads. The studied parameters were: the steel fiber volumetric ratio (1.5%,1.75% and2%), diameter of tension steel bars (12mm, 16mm and 20mm) and the repeated loading regime in which three types of loading were used depending on the minimum to maximum ratio of the applied load. The first loading regime with ratio of 0% with 0 kN for the minimum load while the maximum was the load beyond that causes yielding of steel bars and this is determined from the previous monotonic load test. The second type with 27% ratio (30 kN for the minimum and 105-110 kN for the maximum). The last type was with 20% ratio (the minimum12 kN and the maximum 60 kN).It should be mentioned that 10mm bar diameter was used to the top reinforcement and stirrups for all beams. The mid-span deflection as well as cracks propagation were recorded for each beam throughout the test. The main results showed that the adopted spliced length of tension steel bars was sufficient in monotonic load but insufficient under the action of high number of cycles of the repeated load. In addition, there were beams of splice failure that having low steel fiber ratio or larger diameter of tension steel bars.


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 LAP SPLICING HIGH TENSILE STEEL BARS IN REACTIVE POWDER CONCRETE BEAMS EXPOSED TO REPEATED LOADING
تاثير وصلات تراكب القضبان الفولاذية عالية الشد في عتبات خرسانة المساحيق الفعالة المعرضة لأحمال متكررة

Authors: Hisham M. Al-Hassani --- Qais Abdul Majeed Hassan --- Faten Fadhil Saleem
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2017 Volume: 21 Issue: 3 Pages: 47-59
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

This research is an experimental study to evaluate the effect of lap splice of high-strength steel bars in reactive powder concrete beams exposed to repeated loading. Seven Reactive Powder Concrete (RPC) beams whose tension steel bars were spliced at mid-span and one RPC beam without lap splice were casted and tested. These beams were simply supported and tested up to failure under the action of two point loads (two beams exposed to monotonic load and five beams exposed to repeated load). The studied parameters were : the repeated loading regime (two different repeated loading regime depending on the minimum to maximum applied load),the lap splice length ( 20 and 30 times diameter of bar diameter), the concrete cover thickness (30mm and 40mm) and adding steel stirrups within the lap splice region. The mid span deflection as well as cracks propagation were recorded for each load step in tested beam. The main results showed that the adopted spliced length of tension steel bars was sufficient in monotonic load but insufficient under the action of greater number of cycles of the repeated load. Also the results showed that better structural performance can be achieved by increasing the length of the lap splice, or increasing concrete cover and providing stirrups within the splice region and that the latter method is the most efficient strengthening method when the beam is exposed to larger number of repeated load cycles.

هذا البحث يتعلق بدراسة مختبريه لتقييم تاثير وصلات تراكب حديد تسليح الشد عالي المقاومة في عتبات مصنعة من خرسانة المساحيق الفعالة ومعرضة لأحمال مكررة باتجاه واحد. تم صب وفحص سبع عتبات من هذا النوع تحتوي عند وسط فضائها على وصلات شد لحديد تسليح عالي المقاومة وواحدة بدونها. أسندت هذه العتبات إسنادا بسيطا وتم فحصها تحت تأثير حملين مركزين لحد الفشل ( عتبتان تحت حمل رتيب (ساكن) وخمس عتبات تحت حمل تكراري). المتغيرات التي تم دراستها هي: طريقة تسليط الحمل المكرر (حيث استخدمت طريقتان لتسليط الحمل اعتمادا على نسبة الحمل الأدنى إلى الحمل الأقصى), طول وصلة التراكب ( 20× قطر الشيش و 30×قطر الشيش), سمك الغطاء الخرساني ( 30ملم و40ملم) و اضافة اتاري ضمن منطقة وصلة تراكب حديد التسليح . تم اخذ قراءات الهطول ( deflection) عند منتصف العتبة وكما تم تأشير التشققات الحاصلة أثناء الفحص. تبين بعد إجراء الفحص أن طول وصلة تراكب حديد تسليح الشد العالي المقاومة الذي تم تبنيه كان كافيا تحت تاثير الفحص الستاتيكي ولكن هذا الطول لم يكن كافيا عند تعرض بعض النماذج لعدد كبير من دورات التحميل المتكرر. تبين ايضا انه بالامكان الحصول على اداء انشائي افضل بزيادة طول وصلة التراكب او زيادة الغطاء الخرساني او بتوفير حديد اتاري ضمن منطقة التراكب والمعالجة الاخيرة هي افضل الطرق عند تعرض العتبة الى دورات تحميل كبيرة.


Article
Response of Laced Reinforced Concrete One Way Slab to Repeated Loading
إستجابة البلاطات الخرسانية المسلحة الاحادية الاتجاه والحاوية على حديد متعرج للاحمال المتكررة

Authors: Abaas Abdulmajeed Allawi عباس عبد المجيد علاوي --- Hussain Askar Jabir حسين عسكر جابر
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2016 Volume: 22 Issue: 9 Pages: 36-54
Publisher: Baghdad University جامعة بغداد

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Abstract

Test results of nine reinforced concrete one way slab with and without lacing reinforcement are reported. The tests were designed to study the effect of the lacing reinforcement on the flexural response of one way slabs. The test parameters were considered is the lacing steel ratios of (0, 0.0025, 0.0045, and 0.0065), flexural steel ratios of (0.0025, 0.0045, and 0.0065) and span to the effective depth ratios of (11, 13, and 16). Two specimens had no lacing reinforcement and the remaining seven specimens had the lacing reinforcement. Four point bending test were carried out, one of the specimens was tested under the static load applied gradually up to failure and the other specimens were tested under repeated load (5 cycles) loading-unloading to 80% of the ultimate load of the control specimen then loaded manually by the hydraulic jack up to failure. The specimens showed an improving in ultimate load capacity ranged between (54.54% - 100%) as a result of increasing the lacing steel ratio to (0.0065) and decreasing the span to effective depth ratio by 31.25% respectively with respect to the control specimen. Additionally the using of lacing steel reinforcement leads to reducing the residual deflection by about (57.24%) for the specimen with the largest lacing reinforcement compared with the control specimen (without lacing reinforcement).

تم في هذا البحث مناقشة النتائج العمليه لتسعة بلاطات خرسانيه احادية الاتجاه مسلحه وحاويةعلى تسليح متعرج. ان الغرض من هذا البحث هو دراسه تأثير استخدام التسليح المتعرج على سلوك واستجابة البلاطات الاحادية الاتجاه. وكانت المتغيرات هي نسبة حديد التسليح المتعرج وهي(0.0025,0, 0.0045 , 0.0065), نسبة الحديد الرئيسي وهي (0.0025, 0.0045 , 0.0065) ونسبة الطول الصافي الى العمق الفعال للبلاطة وهي (13,16 , 11). اثنان من العينات لاتحتوي على حديد متعرج اما السبعة المتبقيه فكانت جميعها تحتوي على حديد التسليح المتعرج. تم فحص احدى العينات الغير حاوية على حديد متعرج ستاتيكيا الى الفشل بينما تم فحص العينات المتبقية تحت تاثير الاحمال المتكررة بخمسة دورات تحميلية الى حد 80% من قيمة الحمل الاقصى للعينة المفحوصة ستاتيكياً ثم تحميل العينة الى حد الفشل .بينت النتائج العملية بان التحمل الكلي للبلاطات تحسن بمقدار (%54,54) نتيجه لاستخدام الحديد المتعرج بنسبة (0.0065) و بمقدار (%100) كنتيجة لتقليل نسبة الطول الصافي الى العمق الفعال بمقدار (31,25%) للبلاطات الحاوية على حديد متعرج بنسب متساوية. من ناحيه اخرى فأن استخدام الحديد المتعرج قلل وبشكل ملحوظ مقدار الهطول الدائمي للبلاطات بنسبة (57,24%) للبلاطة ذات اعلى نسبة تسليح متعرج مقارنة مع البلاطة بدون حديد تسليح متعرج.

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