research centers


Search results: Found 8

Listing 1 - 8 of 8
Sort by

Article
Effect of Using Internal Steel Plates for Shear Reinforcement on Flexural Behavior of Self-Compacting Concrete Beams

Authors: Amer M. Ibrahim --- Zeyad S. M. Khaled --- Iman M. Abdul Ameer
Journal: AL-NAHRAIN JOURNAL FOR ENGINEERING SCIENCES مجلة النهرين للعلوم الهندسية ISSN: 25219154 / eISSN 25219162 Year: 2017 Volume: 20 Issue: 5 Pages: 1071-1082
Publisher: Al-Nahrain University جامعة النهرين

Loading...
Loading...
Abstract

This research was conducted to investigate the effect of using internal steel plates for shear reinforcement on flexural behavior of SCC beams instead of using traditional reinforcement bars (stirrups) and to study the effect of their spacing and thickness on strength. The experimental work included destructive tests on six SCC beams under two-point load. The results showed that the yield loads in all of the beams with steel plates were lower than the reference beam by (5.21%) on average, the deflection at yield load was higher by (13.72%) on average and the ultimate loads were lower by (6.77%) on average except in one beam where it was higher by (0.37%). It was also found that the ultimate deflection in beams with internal shear steel plates was lower by (10.01%) on average except in the aforementioned beam where it was higher by (2.31%). Ductility in all beams with steel plates was lower by (20.08%) on average and the strain before a load of (200kN) was higher in the longitudinal reinforcement and lower in shear steel plates and vice versa after a load of (200kN). Theoretical analysis was also carried out for all beams using the finite element program ANSYS (version 15) where theoretical results of load versus mid-span deflection relations, longitudinal reinforcement strain, shear reinforcement strain, variations of neutral axis depths and cracks patterns showed good agreement with experimental ones. Finally, some specific further studies were recommended.

تم إجراء هذا البحث للتحري عن تأثير استخدام صفائح الفولاذ الداخلية لتسليح القص على تصرف الانثناء في العتبات الخرسانية ذاتية الرص بدلاً من قضبان التسليح التقليدية (الحلقية) ودراسة تأثير تباعدها وسمكها. وقد تضمن العمل المختبري فحص ستة عتبات خرسانية ذاتية الرص فحصاً أتلافيا تحت حمل مسلط على نقطتين. وقد أظهرت النتائج أن أحمال الخضوع للعتبات ذات الصفائح الفولاذية كافة هي اقل بمعدل (5.21٪) وأن الانحناء عند حمل الخضوع كان أعلى بمعدل (13.72٪) وأن الأحمال القصوى كانت أقل بمعدل (6.77٪) فيما عدا عتبة واحدة إذ كانت أعلى بنسبة (0.37٪). كما وجد أن الانحناء الأقصى في العتبات ذات الصفائح الفولاذية كافة هو أقل بمعدل (10.01٪) فيما عدا عتبة واحدة إذ كانت أعلى بنسبة (2.31٪). وأن المطيلية في العتبات ذات الصفائح الفولاذية كافة هي أقل بمعدل (20.08٪) وأن الانفعال قبل وصول الحمل ( 200كيلو نيوتن) هي أعلى في التسليح الطولي وأقل في الصفائح الفولاذية، والحالة معكوسة بعد تخطي الحمل (200كيلو نيوتن). وقد تم إجراء التحليل النظري لكل عتبة أيضاً باستخدام برنامج العناصر الدقيقة (ANSYS version 15) حيث أظهرت النتائج النظرية لعلاقة الحمل بالانحناء في منتصف طول العتبة توافقاً جيداً مع النتائج المختبرية. وختاماً تمت التوصية بدراسات مستقبلية محددة الهدف.


Article
NON-LINEAR ANALYSIS TO IMPROVE PUNCHING SHEAR STRENGTH IN FLAT SLAB USING Z-SHAPE SHEAR REINFORCEMENT

Loading...
Loading...
Abstract

Currently, flat slabs become one of the widely used structures due to its architectural benefits such as uncomplicated formwork, flexibility and minimum construction time. However, these structures are relatively weak to resist the punching shear due to a considerable lowering in stiffness induced from the development of cracks that resulting from axial and seismic loads. Moreover, the punching failure is considered a brittle failure caused by the transferring of unbalanced moments and shear forces between the structural members. Unfortunately, this may cause a catastrophic collapse, especially in the region of the slab-column. Therefore, many experimental and theoretical studies were done to improve the punching strength of the flat slab. In the current work; a finite element three-dimensional non-linear analysis has simulated by ABAQUS tool to investigate the structural behaviour of flat slab. Two specimens have considered, the first is a flat slab reinforced by ordinary steel reinforcement. While in the second one, a Z-shape shear rebar improvement has been added to the slab-column connection. The proposed model has reflected a reasonable enhancement to the flat slab. The analysis considers different parameters such as punching shear forces, deformations, and stresses of Von-Mises. The outcomes indicate that punching shear strength is increased by approximately 11.1%, and the deflections are decreased by 77.3% when the Z-shape reinforcement is used. In the meantime, stress concentrations were reduced and move from the slab-column connection.


Article
A Review on Flat Slab Punching Shear Reinforcement

Authors: Ahmed Sagban Saadoon --- Abdulnasser Mohammed --- Abbas Haleem K. Hussain
Journal: Journal of University of Babylon مجلة جامعة بابل ISSN: 19920652 23128135 Year: 2019 Volume: 27 Issue: 3 Pages: 44-58
Publisher: Babylon University جامعة بابل

Loading...
Loading...
Abstract

Flat slab system is a concrete plate propped on columns without the existence of beams. During the former century, flat slabs have been used widely in different building types. In general, flat slabs are made from brittle materials and also have a finite depth; thus, flat slabs may undergo to fail due to punching shear or high deflections. Therefore, these criteria should be considered in the design of flat slabs and ignoring both of them had led to several crumbling down to many constructions in the past. To enhance the flat slab performance against failure due to punching and deflections, additional reinforcement should be supplied in the column region. In this paper, a review is presented to study the mechanism of punching shear in flat slabs and describe different types that used for reinforcement against punching shear.

يتكون نظام البلاطة المسطحة من صفيحة خرسانية مثبتة على أعمدة دون وجود عتبات. خلال القرن الماضي، استخدمت البلاطات المسطحة على نطاق واسع في أنواع مختلفة من المباني. بشكل عام، تصنع البلاطات المسطحة من مواد هشة ذات عمق محدود؛ وبالتالي، قد تخضع للفشل بسبب قوى القص أو انحرافات عالية. ولذلك، يجب اخذ هذه المعايير بعين الاعتبار عند تصميم البلاطات المسطحة وان تجاهل اي منهما قد يؤدي إلى انهيار العديد من المباني كما حصل في الماضي. لتحسين أداء البلاطة المسطحة ضد الفشل نتيجة قوة الاختراق اوالانحرافات، لا بد من توفير تسليح إضافي في منطقة العمود. في هذا البحث، سيتم تقديم مراجعة لدراسة آلية قص الاختراق في البلاطات المسطحة ووصف أنواع التسليح المختلفة التي تستخدم في التعزيز ضد قص الاختراق.


Article
Influence of PVC Fiber Reinforcement on Shear Strength in Concrete Beams

Loading...
Loading...
Abstract

This study adopted the investigation of the effect of a material that can be used as an alternative to steel reinforcement of shear in reinforced concrete beams, as the most susceptible to corrosion to which reduces the time service of the concrete structures and increase the maintenance costs is the steel reinforcement of shear for the closeness of surface of concrete. Therefor non-corroding material is needful for concrete structures and PVC fiber reinforcement is chosen. Experimentally nine reinforced concrete beams have been tested to determine the effect of PVC fiber reinforcement on the concrete beam resistance load, the load of cracks, deflection achieved and distribution with dimension of cracks. Three volume fraction ratios were taken for PVC fiber reinforcement (0, 0.25 and 0.5), which were identical to the shear reinforcement used in this research (0,0.29 and 0.54). All the concrete beams were tested with in on one program by applied a center load from the top in the middle to the failure load and the results were impressive. The specimens containing the PVC fiber reinforcement percentages achieved a remarkable increase in the crack and ultimate load of the concrete beams before and after cracks with direct effect in changing the failure type. While the deflection achieved due to the increase in PVC fiber percentage is more than the allowable deflection in the ACI Code equations of the reinforced concrete beams and more of these if the use of PVC fiber and steel reinforcement of shear together. A smaller measurement of the maximum cracks width was achieved by using advanced percentages of PVC fiber and shear reinforcement (0.5 and 0.54) respectively.


Article
EFFECT OF STEEL PLATES ON SHEAR STRENGTH OF WIDE REINFORCED CONCRETE BEAMS
تأثير صفائح الحديد على مقاومة القص للعتبات الخرسانية المسلحة العريضة

Loading...
Loading...
Abstract

In this study, shear behavior of reinforced concrete wide beams was investigated experimentally. The experimental program consisted of four wide beams of 45 MPa concrete compressive strength tested with a shear span-depth ratio (a/d) equal to 4.52. One of the tested wide beams had web reinforcement as a control specimen, and the other three specimens had no transverse reinforcement but contained vertical shear steel plates. The flexure mode of failure was secured for all of the specimens to allow for shear mode of failure. The key parameters covered in this investigation were the effect of the existence solid and hollow vertical steel plates on the shear capacity of the tested wide beams. The study shows that the contribution of vertical steel plates to the shear capacity was significant and directly proportional to the existence and direction of the steel plates. The increase in the shear capacity ranged from 9.52% to 47.62% for the range of the tested beams compared with the control beam. Transverse vertical steel plates with voids were more effective in the contribution of the shear strength of wide beams and enhances the ductility of the wide beams.

مقاومة القص للعتبات الخرسانية المسلحة العريضة تم تحريها عمليا, تضمن البرنامج العملي صب وفحص اربع نماذج من العتبات الخرسانية المسلحة العريضة ذات مقاومة انضغاط للخرسانة مقدارها 45 MPa فحصت العتبات بنسبة فضاء قص الى العمق الفعال بمقدار4.52 , كانت احدى هذه العتبات العريضة لها تسليح قص وهي العينة المرجعية, اما العتبات الثلاثة الاخرى فكانت بدون حديد تسليح للقص وانما احتوت على صفائح من الحديد ثبتت بصورة طولية وعرضية لمقاومة القص . نمط الفشل للانثناء قيد او أمن من اجل الحصول على نمط فشل قصي, العوامل الاساسية التي تناولها هذا البحث هي تأثير وجود صفائح الحديد الشاقولية الصلدة والمجوفة على تحمل القص للعتبات العريضة تحت الاختبار. اظهرت الدراسة ان مساهمة صفائح الحديد الشاقولية في تحمل القص مهمة ولها علاقة مباشرة بوجود واتجاه هذه الصفائح. ان زيادة تحمل القص للعتبات تحت الاختبار تراوح (9.52% to 47.62%) مقارنة مع العتبة المرجعية. وان صفائح الحديد الشاقولية بالاتجاه العرضي للعتبة كان لها تأثير ومساهمة اكثر في زيادة تحمل القص للعتبات العريضة وساهم في تحسين المطيلية لها.


Article
IMPROVING SHEAR STRENGTH OF THICK HOLLOW CORE SLABS BY USING LIGHTWEIGHT HIGH STRENGTH CONCRETE PRODUCED FROM RECYCLED CRUSHED CLAY BRICK AND IRON POWDER WASTE

Authors: Yousif Nassif Sabr --- Husain Khalaf Jarallah --- Hassan Issa AbdulKareem
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 6 Pages: 128-146
Publisher: Al-Mustansyriah University الجامعة المستنصرية

Loading...
Loading...
Abstract

This investigation provides an experimental study about structural behavior of reinforced hollow core slab (HCS) by using recycled lightweight material. Six hollow core slab specimens were casted with dimensions 1200mm length, 450mm width and different thickness (200mm, 250mm and 325mm). The shear reinforcement was used for each thickness to resist the shear failure that occur in thick hollow core slab. The Recycled materials were crushed clay brick and iron powder waste. The crushed clay brick was used as a coarse aggregate instead of gravel to a get lightweight concrete. The hollow core slab specimens were tested with age 28-day. The test was done by applied two line load up to failure. The experimental results showed an increase in the shear strength up to 50% and decrease in the maximum deflection up to 50% with increasing thickness specimen. Also the experimental results showed an increase in the shear strength up to 50% and increase in the maximum deflection up to 50% with using shear reinforcement compare with hollow core slab specimens without shear reinforcement. From the experimental results of this investigation can be avoid the shear failure and change the mode of failure from the shear to flexural failure.


Article
Finite Element Analysis of Shear Transfer Strength of SFRC Models
بموديلات العناصر المحددة SFRC تحليل مقاومة القص المباشر لنماذج

Author: Moayad M. Kassim1 مؤيد محمد قاسم1
Journal: kirkuk university journal for scientific studies مجلة جامعة كركوك - الدراسات العلمية ISSN: 19920849 / 26166801 Year: 2016 Volume: 11 Issue: 3 Pages: 81-99
Publisher: Kirkuk University جامعة كركوك

Loading...
Loading...
Abstract

Direct shear stress may be the main reason in failure of some typical concrete members like corbels, brackets and ledger beams. The theoretical analysis of these members simulated as push-off specimens were based on a two-dimensional plane stress by finite element method. The main variables to be studied theoretically were fiber percentage, the shear rebar reinforcement ratio crossing the shear plane at right angles and the actual distribution of shearing stress in the shear plane. The comparison shows that the theoretical results are in good agreement with the experimental values conducted by other researchers

إجهاد القص المباشر قد يكون السبب في فشل بعض الأعضاء الإنشائية الخاصة مثل سناد العتبات والرفوف والعتبات القصيرة(corbels, brackets and ledger beams) . التحليل النظري لهذه الأعضاء قلد بنماذج الدفع(push-off) على أساس إجهاد ثنائي الأبعاد للمقاطع باستخدام طريقة العناصر المحددة. المتغيرات الرئيسية التي درست نظريا كانت نسبة الألياف, نسبة التسليح بالقضبان التي تجتاز مقاطع القص بزوايا عمودية والتوزيع الحقيقي للاجهادات في مقاطع القص. المقارنة بين النتائج النظرية والقيم المستحصلة من التجارب العملية التي أجريت من قبل باحثين آخرين تظهر توافقا جيدا.


Article
Enhancing the Punching Behavior of High Strength Concrete Flat Plates Subjected to Repeated Load by Using Shear Reinforcement

Authors: Nameer Abdalameer Alwash --- Ghalib Mohsin Habeeb --- Hussein Talab Nhabih
Journal: Journal of University of Babylon مجلة جامعة بابل ISSN: 19920652 23128135 Year: 2018 Volume: 26 Issue: 3 Pages: 212-227
Publisher: Babylon University جامعة بابل

Loading...
Loading...
Abstract

The present study includes an experimental and numerical investigations for the punching behavior of shear reinforced square simply supported flat plates of high strength concrete (HSC) subjected to repeated load. The experimental program consists of testing four flat plate models. They were of the same overall dimensions of plate, (900×900×100) mm and dimensions of column (150×150×300) mm. The main variable has been considered in the experimental study is: type of shear reinforcement (three models): closed stirrups, headed shear studs and bent bars. Finally, a fourth model (without shear reinforced) served as control model. From the results of this work, It was found that the closed stirrups is the best type of shear reinforcement because this type is highly increase punching shear strength (about 92%) , rotation capacity, simple and cost-effective. Three-dimensional nonlinear finite element analysis has been carried out to conduct the numerical investigation of the general behavior of HSC flat plat models. ABAQUS (Version 6, copyright 2013) computer program was used in this work. A comparison between numerical and experimental results showed good validity of the numerical analysis where the average difference ratio based on the ultimate load was less than 3.67% for all analyzed models.

تتضمن الدراسة الحالية التحري العملي والتحليلي لسلوك الثقب لتسليح القص السقوف المستوية مربعة الشكل والمسندة بإسناد بسيط والمصبوبة باستخدام خرسانة عالية المقاومة و المعرضة لحمل تكراري. يتألف البرنامج العملي من فحص اربع نموذج سقوف مستوية بنفس الأبعاد الكلية لجميع السقوف ( 900×900×100 ) ملم والأعمدة ( 150×150 ×300 ) ملم. أهم متغير أخذت بنظر الاعتبار في هذه الدراسة هو نوع تسليح القص (ثلاث نماذج): الاطواق الفولاذية المغلقة, مسامير القص الفولاذية و القضبان الفولاذية المنحنية. اخيرا, النموذج الرابع ( بدون حديد تسليح قصي ) يعمل كنموذج مرجعي. من نتائج هذا العمل, وجد بأن الاطواق الفولاذية المغلقة افضل انواع تسليح القص لان هذا النوع يعطي زيادة عالية في مقاومه القص الثاقب ( حوالي 92%) و استيعابيه الدوران, سهل واقتصادي. التحري التحليلي قدم أنموذجا لا خطيا بالاعتماد على عناصر ثلاثية الأبعاد ملائمة لتحليل نماذج السقوف المستوية المصبوبة باستخدام خرسانة عالية المقاومة باستخدام البرنامج الحاسوبي ( ABAQUS , الإصدار6 - النسخة 2013 ). المقارنة بين النتائج العملية والتحليلية بينت توافق جيد حيث كان معدل نسبة الاختلاف بالاعتماد على الحمل النهائي لا يزيد عن 3.67% لكل النماذج المحللة.

Listing 1 - 8 of 8
Sort by
Narrow your search

Resource type

article (8)


Language

English (8)


Year
From To Submit

2019 (4)

2018 (1)

2017 (1)

2016 (1)

2015 (1)