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Article
EXPERIMENTAL STUDY ON THE BEHAVIOR OF DIFFERENT TYPES OF STEEL FIBER REINFORCED CONCRETE MIX OF TWO WAY-SLABS SUBJECTED TO DIFFERENT HEAT TEMPERATURE

Author: Omar Shamal Farhan
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 1 Pages: 26-42
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

This research aims to study the influence of steel fibers on the behavior of eighteen reinforced concrete (RC) slabs under different temperatures. The main investigated parameters in this paper were concrete type i.e. Normal-Strength Concrete (NSC), High-Strength Concrete (HSC) and Light-Weight Concrete (LWC), the effect of various parameters such as; amount of steel fiber ratio (0% and 2%) on failure load, crack patterns, and load- deflection response, have been studied. In these slabs the amounts of reinforcements were kept constant. The study also includes the type's failure and effect of types of concrete when all specimens are exposed to several temperature levels (25Co, 400Co, 600Co). It showed that, there is a reduction of strength with the increase of temperature. The test results show that as the volume of the steel fibers increase the punching shear strength increased and the presence of fibers delay the appearance of the first crack in the slab and gave less deflection than the slab without fibers.


Article
SUGGESTED EQUATIONS FOR MECHANICAL PROPERTIES OF SELF COMPACTING CONCRETE STRENGTHENED WITH STEEL FIBERS AND EFFECT OF SUCH FIBERS ON SHEAR CAPACITY OF SIMPLY SUPPORTED DEEP BEAMS UNDER AXIAL LOADS

Authors: Wissam Khadum Al-Saraj --- Sarra’a Dhiyaa Jaafer
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 4 Pages: 119-131
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Deep beams are structural elements that commonly design for bridges, girders, foundation walls, pile caps and others. Also, using Self Compacting Concrete (SCC) mix for deep beam is a suitable choice for deep beams because of reinforcement congestion therein. The main objective of this work is to study the shear capacity of SCC reinforced concrete deep beams subjected to axial load, so that both of experimental and analytical works are done. The experimental work consists four simply supported deep beams casted by using SCC mix with steel fibers and tested. All these beams have dimensions 1300mm length, 350mm high, 150mm width and have been subjected to axial force with (100) kN value and then subjected to two-point loads. The variables of this work are vertical and horizontal shear reinforcement and steel fibers ratio in order to study their effects on first crack load and ultimate load and mid span deflection. From the experimental results obtained all the tested beams failed by diagonal splitting mode with some crushing at support zones (in some beams). The second part is the analytical study of this research, including presents proposed equations to estimate the mechanical properties as: compressive strength f`cf, splitting tensile strength ftf, modulus of rapture frf, and modulus of elasticity Ecf of fibrous SCC.


Article
IMPROVING MECHANICAL PROPERTIES OF LIGHTWEIGHT FOAMED CONCRETE USING SILICA FUME AND FIBERS

Authors: Suhad Mohammed Abd --- Dhamyaa Ghalib Jassam
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 2 Pages: 184-199
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Lightweight foamed concrete (LWFC) is characterized as a light in self-weight, self-compacting (no need vibration), self-leveling, and thermal and sound isolation. The application of (LWFC) in the building construction is limited because of its the low strength and the low ductility. In this study the workability of the fresh mix of (LWFC), the hardened properties include, compressive strength, tensile splitting strength, flexural strength, and modulus of elasticity were evaluated. This study focuses mainly on the effect of the adding of silica fume and fibers on the mechanical properties of (LWFC). Silica fume was added as 5% and 10% by the weight of cement. Steel fiber and polypropylene fiber volume fraction were of (0.2%, 0.4%), While the hybrid fibers (steel+ polypropylene) volume fraction was (0.2% steel+0.2%PP), and (0.4%steel+0.2%PP) of the total mix volume. The results of the program test show that the increase of silica fume improves the mechanical properties of (LWFC) significantly. The adding of fibers to the (LWFC) reduces the flowability and improves the mechanical properties. The hybrid fibers mix (0.4% steel+0.2% PP) presented the best test result of the mechanical properties as (10%,21%,53%, 24.4%) for the compressive strength, flexural strength, tensile splitting strength, and modulus of elasticity, respectively.


Article
Effect of Use Recycled Coarse Aggregate on the Behavior of Axially Loaded Reinforced Concrete Columns
تأثير استخدام الركام الخشن المعاد تدويره على تصرف الأعمدة الخرسانية المسلحة محورية التحميل

Author: Omar Shamal Farhan
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2019 Volume: 25 Issue: 10 Pages: 88-107
Publisher: Baghdad University جامعة بغداد

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Abstract

Nowadays, the use of recycled waste construction materials instead of aggregates is becoming popular in construction owing to its environmental benefits. This paper presents an experimental and analytical campaign to study the behavior of axially loaded columns constructed from recycled aggregates. The latter was used instead of natural aggregates, and they were collected from the waste of previous concrete constructions. Different concrete mixtures made from varying amounts of recycled aggregates ranged from 0 to 50% of the total coarse aggregate were conducted to achieve 28 MPa. The effect of steel fibers is another investigated variable with volumes ranged from 0 to 2% concerning concrete’s mixture. The experimental results showed that the concrete strength is dependent on the amount of recycled aggregates. When the recycled aggregates were less than 30% of the total aggregates, they had a negligible effect on concrete strength and the load carrying capacity of the column models were improved. Also, the presence of steel fibers enhanced the load carrying capacity of the columns constructed from concrete with recycled aggregates of more than 30%. Finite element analysis (using ANSYS 16.1 software program) was conducted to simulate the experimental investigations, and they achieved good agreements with the test results.

في الوقت الراهن، أصبح استخدام مواد البناء المعاد تدويرها بدلاً من الركام أمراً شائعاً في البناء بسبب فوائده البيئية. تم دراسة السلوك العملي والتحليلي لأعمدة خرسانية محورية التحميل باستبدال نسب من الركام بركام معاد تدويره. حيث تم استخدام نسب تتراوح من 0 إلى 50٪ من إجمالي الركام الخشن (الحصى) لتحقيق مقاومة خرسانة مقدارها 28 نت/ملم2. إن تأثير الألياف الفولاذية هو متغير آخر تم فحصه بنسب تتراوح من 0 إلى 2٪. أظهرت النتائج التجريبية أن قوة الخرسانة تعتمد على كمية الركام المعاد تدويره. حيث عندما كانت نسبة الركام المعاد تدويره داخل الخلطة أقل من 30٪ من نسبة الركام الطبيعي، فان تأثير هذه النسبة ضئيل على قوة الخرسانة وتم تحسين قدرة تحمل الحمل الأقصى لنماذج الأعمدة. كذلك فإن وجود الألياف الفولاذية قد عزز القدرة على زيادة الحمل الأقصى للأعمدة التي تحتوي على نسبة ركام معاد تدويره لأكثر من 30٪. تم استخدام برنامج تحليل العناصر المحددة (ANSYS) وذلك لمحاكاة الجزء العملي وحققت توافقات جيدة مع النتائج العملية.

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