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Article
Repairing of Reactive Powder Concrete T-Beams Containing Web Opening by CFRP Strips
اصلاح عتبات خرسانة المساحيق الفعالة ذات المقطع T الحاوية على فتحات في منطقة الجذع بشرائخ االلياف

Authors: Mazin B. Abdulrahman --- Husham Mohammed Rashid
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 1 Pages: 9-19
Publisher: Tikrit University جامعة تكريت

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Abstract

In modern buildings, transverse openings are often used beams for the purpose of supplying and service pipes. Due to the presence of the openings in the concrete beams lead to the formation of cracks around the openings due to the stresses concentration in a small area above and below of the opening. The repairing, maintenance, and upgrading of structural members, are maybe one of the most pivotal problems in civil engineering applications. In this research, an experimental work is conducted to study the behavior of the reinforced RPC T-beams that containing openings and repair this beams using CFRP strips. The Experimental program of the present study includes two parts, the first part includes testing of seven reinforced reactive powder concrete RPC T-beams, which casted and tested, one beam is without opening as a reference beam and the rest, were provided with an opening. and these beams are divided into two groups. The first group was used to study the effect of the openings shape (circular and square) and the second group was used to study the effect of the openings locations, which consists three locations (Lc/2, Lc/3 and Lc/4). These are measured from the support center to the openings center. While the second part including a repaired all beams in the first part the using carbon fiber polymer. The test results indicated that the presence of openings in the beams web caused a reduction in the reinforced RPC T-beams ultimate load carrying capacity with about (10-55)%, Also lead to increasing in deflection compared to control beam before repairing at same loading. Studying the shape effect showed that the beams with square openings have average ultimate load carrying capacity lower by 36% compared with the control beams. While beams with containing circular openings have average ultimate load carrying capacity lower 29%. From the test results, it could be concluded that the presence of the openings in the shear region led to a decrease in ultimate load carrying capacity a about 38% to 49% for opening of opening at (Lc/3 and Lc/4) respectively. While the presence of openings in the flexural region led to a decrease in the ultimate load carrying capacity rate of 11%. Related to the repairing study part it was found that the average ultimate load carrying capacity for repairing beams was 103% compared with the not repairedbeams.


Article
Effect of Adding Mixture of (Concrete Waste and Asphalt Waste) on the Properties of Gypseous Soil
تأثير اضافة مزيج (مخلفات الخرسانة ومخلفات االسفلت) على خصائص التربة الجبسية

Authors: Adnan Jayed Zedan --- Rizgar Ali Hummadi --- Sarah Abdullah Hussein
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 1 Pages: 20-25
Publisher: Tikrit University جامعة تكريت

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Abstract

The Gypseous soil which is used is taken from Tikrit city in Salah Aldeen governorate and specially from Tikrit University from a depth (1.5-2) m. It's type is sandy gravely with a small percentage of silt and clay while the percentage of gypsum is (34-36) %. The tests on soil are standard proctor compaction, direct shear, collapsibility and California bearing ratio. The number of samples is (70). The effect of adding concrete waste (2, 4, 6 and 8%) and waste of Asphalt mixture (2, 4, 6 and 8) % on dry soil, as well as the effect of mixture of the optimum percentages of both additions on the properties of gypseous soil, is the aim of the study. Adding concrete waste at optimum percentage (6) % causes an increase inmaximum dry density at (16)% and a decrease in optimum moisture content at (5)%. Whereas adding concrete mixture waste in its optimum percentage (2) % caused a decrease in maximum dry density values with an increase of optimum moisture content, and when adding a mixture of optimum percentage of waste, an increase happened in the M.D.D.(14)% with a decrease in O.M.C. at (4) %. Adding theoptimum percentage (8) % for both, the value of cohesion increases (100) % when adding concrete waste with an increase in the angle of internal friction (14)% and a decrease in collapsibility in a percentage of (90)% , while adding waste of asphalt mixture shows an increase in cohesion value (112) % with a decrease in the angleof internal friction (2) % and a decrease in collapsibility in a percentage of (90) %, when adding mixture of optimum percentages the value of cohesion increase (108)% with an increase in angle of internal friction (14)% and a decrease in collapsibility in a percentage of (91) %. Values of California Bearing Ratio in dryand soaked condition increases (49) % when adding (8) % of concrete wastes which is the optimum percentage, while adding waste of asphalt mixture causes a decrease in the value of C.B.R. and the optimum percentage is (2) % , but adding optimum percentages mixture of them causes an increase in values of (52) % in dry condition and (53)% in soaked condition.


Article
The Performance Prediction of The Mixed Convection In an Inclined Circular Tube Filled Porous Media Based on an Intelligent Control

Author: Musa Mustafa Weis
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 2 Pages: 9-14
Publisher: Tikrit University جامعة تكريت

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Abstract

The porous media has a significant impact on the heat transfer and storage properties. The present study focuses on the heat transfer of the mixed convection through a circular tube that filled with a porous media at different angles using a neural network. An experiment had been performed for the Rayleigh number range from 108.54 to 907.73 and the Peclet number range 30.3.-510 using three tests for the heat flux. The result shows the mean relative error about 7.913% and the coloration coefficient (R2) Is 99.18% for the train data. The mean relative error about 6.641% and the R2 is 99.46%, for the test data. The results showed that effectiveness of ANN in the predicted thermal performance in thermal engineering applications such as heat transfer modeling using porous media with airflow.


Article
Flexural Behavior of Concrete Composite Beams with New Steel Tube Section and Different Shear Connectors
تصرف الانثناء للعتبات الخرسانية المركبة بإستخدام مقاطع حديدية مجوفة جديدة و روابط القصية مختلفة

Authors: Amer M. Ibrahim --- Wissam D. Salman --- Fahad M. Bahlol
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 1 Pages: 51-61
Publisher: Tikrit University جامعة تكريت

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Abstract

Hollow sections of steel are widely used in many engineering applications as structural members. This paper aims at studying the flexural behavior of a composite beams with steel tubes sections through a series of bending tests in order to study and examine theinfluence of the steel tube section shape, (square, rectangular and hexagonal) with the same shear connector type (headed stud or angle or perfobond) on its flexural behavior and the bending properties of these sections. As well as study the effect of different shear connectors types (headed stud, angle and perfobond) in the same steel tube sections (hexagonal, square, or rectangular) on the flexural behavior of the composite beams. The experimental program (in this work) has been divided into two groups, the first consists of nine specimens tests focusing on three types of steel section. Using shear stud first, angle at second, and perfobond at third as shear connector type. The second group consists of testing nine specimens of composite beams too. This group focuses on testing every steel section (hexagonal, square and rectangular) alone whenusing three types of shear connectors with it. All the specimens are of the same length, width and height (2000, 400 and 130) mm respectively. The tested steel tubes thickness was 2 mm, yield stress of 322 MPa and the ultimate strength was 390 MPa. The resultsshowed that these shapes of hollow steel sections (hexagonal, square and rectangular) sustain the quality of services for the buildings, and these tested specimens are applicable by giving a distinctive strength and stiffness starting from 114 kN as ultimate load reaching to 170 kN. The experimental results proved that the perfobond and angle connector types are clearly effective shear connectors. Shear connector of the perfobond type increased the ultimate load of the composite beams by (6.25-9.74) % compared with the stud shear connector.


Article
Effect of the Gyroscopic Moment, Centrifugal Force and Hydroplaning on the Critical Speed of the Vehicle

Authors: Ibrahem A. Muhsin --- Abdalrahman M. Shwikh
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 2 Pages: 39-48
Publisher: Tikrit University جامعة تكريت

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Abstract

Driving vehicles on curved roads is dangerous because of the risk of accidents. This is due to the centrifugal force, gyroscopic moment and hydroplaning of the vehicle, ending with vehicle slipping or tipping. The aim of this research is to find the critical speed under any one of the above mentioned risks. The water pressure under the vehicle tires was calculated using Matlab R2017a in order to find the pressure value that able to lift the vehicle causing slipping and then going out of control. The effect of many parameters, on the vehicle hydroplaning have been studied. These parameters are tire width, wheel load, and water layer thickness. While for vehicle slipping due to the centrifugal force or the gyroscopic moment, the following parameters have been studied. These parameters are height of vehicle gravity center, vehicle width, radius of the circular path and track angle. The results showed that the gyroscopic torque negatively affects the critical velocity of the vehicle, and it reduced it about 0.549%. The centrifugal effect is the has the greatest influence on the gyroscopic effect, and the gyroscopic effect pushes the vehicle outward and increases the radius of the rotation, while the gyroscopic couple effect, at low radius. of low rotation, is very small. Gyroscopic impact is increased by increasing the radius of the rotation path. The result also showed the increase of the road surface angle and surface at the turning the influence positively on the safe speed of the vehicle at all the above variables.


Article
Appraisal of Risk Factors which Influence the Construction of the School Buildings in Northern Iraq

Authors: Khalil Ismail Wali --- Nazik Imad Saber
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 2 Pages: 1-8
Publisher: Tikrit University جامعة تكريت

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Abstract

Construction projects have a unique nature which takes the high risk due to many interrelated parameters. This study aims to investigate and assess the influence of the risk factors that occurred during the lifecycle of a school project which comprises the design phases, implementation and operation and maintenance. In addition to examining the effects of the internal and external risk factors that contributed by the school’s construction, in order to avoid the risk occurrence during the lifecycle of the projects. A questionnaire was prepared and distributed to a number of engineers in the Governmental Sectors (School buildings sector, Kirkuk Governorate sector, and Municipal sector in Kirkuk Government and Buildings sector in Erbil Governorate) in northern Iraq. The collected data which were analyzed using the relative importance index (RII) and matrix analysis to prioritize the project risks. The analysis results were revealed that the most significant risk factors in the school’s project lifecycle and construction were providing a proper water supply and storage system to maintain a continuous good quality of water, incompetent contractors and sub-contractors for completing school buildings, using proper construction materials to avoid cracks in the building, lack of safety in project site, keep the toilets clean to avoid diseases, and providing an emergency exits were considered the most significant risk factors in construction of school buildings.


Article
Mechanical and Structural Properties of a Lightweight Concrete with Different Types of Recycling Coarse Aggregate
الخصائص الميكانيكية والانشائية للخرسانة الخفيفة باستخدام أنواع مختلفة من الركام الخشن الخفيف

Authors: Muyasser M. Jomaa’h --- Baraa Thaar Kamil --- Omer S. Baghabra
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 1 Pages: 33-40
Publisher: Tikrit University جامعة تكريت

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Abstract

In the light of the world's technological development in the construction field and the continuous need to apply high-efficiency building materials because old methods are no longer used after the advent of the solutions characterized by fast applications and maximum protection in addition to reducing costs and increasingthe sustainability of the establishment and its design age. The lightweights of various installations are an urgent need to decrease the dead loads. Therefore, this study is a local focus on replacing the normal coarse aggregate with lightweight coarse aggregate (claystone (bonza), rubber, thermostone and polystyrene) in various volumetric ratios of (25, 50 and 75) % in addition to a preparation of reference mix. For the purpose of identifying and studying the important specifications the new concrete which contributes to the selfload reduction of the concrete by reducing the total density of the mixture, models of cylinders and standard prisms were prepared, to evaluate the compressive strength and the splitting tensile strength respectively. In addition to that the modulus of rupture and the unit weight, where carried out. The tests results indicated a drop in the mechanical properties of the concrete with increase in the lightweight coarse aggregate, mechanical properties values: compressive strength, rupture modulus, splitting tensile strength and flexural strength were between (10.66-28.99) MPa (1.122-3.372) MPa, (3.606-6.83) MPa and (20.101-25.874)MPa compared with a reference mixes (38.44MPa), (3.969MPa), (10.476MPa) and (26.940)MPa respectively for mixes of (25, 50 and75)% with different light coarse aggregate , also the values of an oven-dry density were between (1665.5-2287.58)kg/m3 compared with reference mixes (2426.41kg/m³). The best concrete mix was (M7, M10) of low density (1598.4 kg/m3) and (1580.4) kg /m3 and the compression strength within the permissible limits (15.47) MPa.


Article
Assessment of the Affecting Elements on the Quality of Life and Human Well-being in Congested Urban Centers; Case Study: Sulaymaniah City

Authors: Othman Kareem Mohammed --- Hoshyar Qadir Rasul
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 2 Pages: 49-58
Publisher: Tikrit University جامعة تكريت

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Abstract

This Study is an empiric-analytical research in city planning discipline was conducted in Sulaymaniyah city from Dec. 2015 until July 2017. Geographically Sulaymaniah situates north-east of Republic of Iraq. Like many other urban centers, Sulaymaniyah city as one of the congested urban areas in Kurdistan Region, is almost overpopulated and congested, resulting in accumulated problems in health-, economical-, services, technical-, social- and planning affairs, which leads to permanent degrading of the natural, and social environment and thus impact on the quality of life, Thus the main concern of this study is firstly finding out the reasons facts indeed responsible for the above described unsatisfied situations and then try to answer the questions whether planning methods (if any) manage to prepare answers to these urgent problems overwhelming the city? The study believes that the cardinal reasons for this situation are the effects of combinations of triple facts, namely: the exponential growth of human population in general- and accompanied problems-, the destroyed balance between rural and urban areas and the political vision of administrative machinery that focus on urban centers by neglecting countryside. The cumulative effect of these facts could be observed in form of many distinctive and at the same time, interlocking elements leads to the problems that mentioned above. Among many elements involving, the study handles, analyzes and discusses only the elements indeed responsible for destroying the visual, physical and health conditions of the city inhabitants in Sulaymaniyah. Used criterion in determining these elements are the terms: active element, Passive Element, Critical element, and buffer element, which give the adequate answer to the arise questions.


Article
Strength of Reinforced Reactive Powder Concrete Hollow Beams
مقاومة عتبات خرسانة المساحيق الفعالة المجوفة المقطع

Authors: Mazin B. Abdulrahman --- Saba Muayad Mahmood
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 2 Pages: 15-22
Publisher: Tikrit University جامعة تكريت

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Abstract

The main objective of this research is to investigate the structural behavior and strength of reinforced reactive powder concrete beams with a hollow section subjected under two point concentrated loading. The experimental work consist of ten beams with dimensions (150mm width×200mm height×1000 mm length), eight of them are hollow beams and two solid beams were cast and tested up to failure. The major parameters adopted in the current research includes the hollowness ratio (10% and15%), hollow location (at top or at bottom), and hollow shape (circle or square). The amount of longitudinal and transverse reinforcement, concrete strength and the other parameters were kept constant for all the specimens. The comparisons between all specimens (hollow and solid) are based on the load carrying capacity, deflection, crack pattern and mode of failures. Results showed that the strength capacity of hollow beam when the hollow lies in the bottom is much higher than for top hollow, and the square hollow will lead to more decrease in the beam strength compared with the circular hollow and this is more evident when the hollowness ratio increases from (10% to 15%).


Article
Utilization of CO2 in Flue Gas for Sodium Bicarbonate Production in a Bubble Column

Authors: Zaid A. Abdel-Rahman --- Zeyad A. Abdullah
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2019 Volume: 26 Issue: 2 Pages: 28-38
Publisher: Tikrit University جامعة تكريت

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Abstract

Utilization of CO2 in flue gases for the production of sodium bicarbonate is an environmentally friendly process. A mathematical model was constructed for the design and simulation of utilizing a low concentration CO2 (2-18%) in flue gas to produce sodium bicarbonate in a bubble column reactor. The model is based on the mass balance equations for three phases (gas, liquid, and solid). Danckwerts theory for mass transfer from the gas phase to the liquid phase coupling with chemical reaction, and crystallization mechanism was used. The effect of process variables; gas molar velocity or flux (G=2.5-10 mole/m2.s), liquid mass flow rate (mL=2800-3400 kg/h), sodium bicarbonate concentration (x1=0.04-0.1), CO2 gas mole fraction (y=0.02-0.18), column height (h=11-33 m), and column diameter (dR=1-3 m) on the objective variables; solid molar velocity (S), CO2 conversion, precipitation zone height (Zi), and crystal size distribution (CSD) were studied. The conversion of CO2 varied from 34% to 71% whereas the particle size range varied from 0 to 400 μm. The particle size range and the CO2 absorption efficiency of about 50% for 20 m column height are in agreement with the literature.

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