Corrosion resistance of aluminum alloy 2024 – T6 at multi variable (temperature and velocity) in sea water

Muthanna Journal of Engineering and Technology

Volume (2), Issue (1), Year (30 June 2013), Pages (14-24)

DOI:10.52113/3/eng/mjet/2013-02-01/14-24

Research Article By:

Hussein Abed Zaidan

Corresponding author E-mail: husain_zaidan2000@yahoo.com

ABSTRACT

This work aimed to study the corrosion resistance of aluminum alloy 2024 – T6 at multi variable temperatures and velocities in seawater. 2024-T6 is widely used in aircraft structures, especially wing and fuselage structures under tension. The specimens were manufactured by dimensions of 1.5 cm length x 1.5 cm width x 0.2 cm thickness, According to ASTM (G71-30). Corrosion test was implemented by using potentiostatic polarization measurements in seawater 3.5%NaCl at a temperature of 25°C, 50°C and 75°C , velocity 1, 2, 3 m/min . The potential of circuit was determined by open circuit depending on AL in electrochemical series after that the rate of cell’s current is changed due to 100± (m v). From result which obtained by Tafel equation. It was found that the corrosion resistance of 2024 – T6 Al alloy, increases with increasing velocity and decreases with increasing of temperature.

Keywords: Corrosion resistance, aluminum alloy, velocity, temperature, seawater.

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Fire flame effect on the strength of self – compacting concrete

Muthanna Journal of Engineering and Technology

Volume (2), Issue (1), Year (30 June 2013), Pages (01-13)

DOI:10.52113/3/eng/mjet/2013-02-01/01-13

Research Article By:

Esam Mohammed Ali, Ali Hadi Adheem and Ahmed Samir Naje

Corresponding author E-mail: hillaured@yahoo.com

ABSTRACT

This study aims to investigate the effect of fire flame on some mechanical properties of self-compacting concrete specimens. To determine the workability, different test methods are adopted in this research such as slump-flow, T50 slump-flow, L-box, U-box and V-funnel. The concrete specimens were subjected to fire flame at the lower surface only to reach temperatures around 400,500 and 600 °C for one hour, then they were cooled gradually to room temperature. After that, they were tested for weight loss, compression, splitting and flexural and compared with specimens not subjected to fire flame (reference mix).
Based on the results of this work, it may found that the compressive strength of self-compacting concrete decreases with fire temperature exposure. The residual values of compressive strength were (71-88) % of the strength for the reference specimens. The flexural strength is more sensitive to fire flame temperatures. The residual flexural strengths were in the range of (58- 81) % of the flexural strength for the reference specimens. The splitting tensile strength was extra sensitive than the compressive strength. The residual splitting tensile strength were in the ranges of (58- 90) % of the splitting strength for the reference specimens. The weight loss of concrete specimens increases with increasing fire temperature. The reduction in weight loss ranged between (3.47-6.17) % relative to reference specimens.

Keywords: SCC, fire flame, warkability, mechanical properties.

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Simulating airborne line scanner imagery

Muthanna Journal of Engineering and Technology

Volume (2), Issue (2), Year (30 December 2013), Pages (83-92)

DOI:10.52113/3/eng/mjet/2013-02-02/83-92

Research Article By:

Rasheed Saleem Abed and A. R. Santhakumar

Corresponding author E-mail: mosul_5@yahoo.com

ABSTRACT

Simulation is used to view or evaluate processes that are costly, difficult to perform or time consuming, or simply for educational and display purposes. In photogrammetry, airborne line scanner imagery differs from normal perspective photography in geometric properties. This work introduces the development of a program used for airborne line scanner image simulation. Two products have been discussed, raster image data and ground coverage.

Keywords: Line scanner, pushbroom, simulation, photogrammetry.

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Micromechanical modeling of short – fiber reinforced polymeric composite

Muthanna Journal of Engineering and Technology

Volume (2), Issue (2), Year (30 December 2013), Pages (73-82)

DOI:10.52113/3/eng/mjet/2013-02-02/73-82

Research Article By:

Kareem N. Hussien

Corresponding author E-mail: kareem_najem@yahoo.com

ABSTRACT

This paper presents a method considering the effect of fiber geometry and volume fraction for predicting the tensile strength, shear stress and Von Mises stress. The finite element scheme for the micromechanical modeling of the behavior of fiber reinforced polymeric composites under external load is developed. The model is used to estimate the stress distribution throughout the composite domain and to identify the location where maximum stresses occur. The ratio between fiber modulus and matrix modulus must be high enough to improve the mechanical properties and to reduce the premature interfacial failure. The prediction of the stress distribution by using a simulation tool could be helpful for more understanding the real reasons behind failure of polymer composites.

Keywords: Polymer composite, finite element, stress distribution, short-fiber reinforced composite.

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Protection of natural rubber from ultraviolet by using anthocyanin pigment

Muthanna Journal of Engineering and Technology

Volume (2), Issue (2), Year (30 December 2013), Pages (61-72)

DOI:10.52113/3/eng/mjet/2013-02-02/61-72

Research Article By:

Mohammed Razzaq Mohammed

Corresponding author E-mail: m.r.alassadi14@gmail.com

ABSTRACT

Anthocynin pigment is one of natural pigments material. Pigments are present in each one of the organisms in the world, and plants are the principal producers. They are in leaves, fruits, vegetables, and flowers. In this study the effect of anthocyanin pigment on protection of natural rubber from UV radiation and effect of pigment on some mechanical and physical behaviour of natural rubber was assessed. Anthocyanin pigment was prepared from chards by filtration method. It was added to NR from (5pphr) to (25 pphr). The samples with anthocyanin and without were exposed to UV for a various periods and then some mechanical and physical tests were carried out for the prepared specimens. The results showed that the tensile strength, modulus of elasticity, hardness and specific weight decreased with increasing of anthocyanin. Elongation increased with increasing of anthocyanin pigment. When samples exposed to UV, the results showed a broad enhancement in the mechanical properties for all samples contained anthocyanin. This research was used a natural and cheap material available largely in plants to protect of polymers from degradation and to improve their properties instead of synthetics pigments that they are harmful and expensive.

Keywords: Natural rubber (NR), anthocyanin, pigment, ultraviolet (UV) mechanical, physical, properties.

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Deterioration of concrete for under-ground structures in Samawa city

Muthanna Journal of Engineering and Technology

Volume (2), Issue (2), Year (30 December 2013), Pages (48-60)

DOI:10.52113/3/eng/mjet/2013-02-02/48-60

Research Article By:

Riadh A. Abbas

Corresponding author E-mail: Readh_56@yahoo.com

ABSTRACT

Concrete is a relatively durable building Materials, it may be failed or damaged due to the effect of some properties of soil components, such as salt, sulfate and underground water, especially when the concrete used in construction of the underground structures. Sulfate and salt (which are dissolved in water) try to penetrate through the concrete and attack it. The attack effects will be on the strength characters of concrete and rebar reinforcements.
The aim of this work is to study the effect of soil components on strength of concrete (for 28 day age) when the concrete is buried in the soil. For achieving this aim of the work, the compressive strength of concrete specimens was tested before and after burying in the ground for the same concrete mix design. The specimens were grouped to be tested under the condition of different periods of burying in the soil for 5 months starting from the casting date. In addition to that, it was investigated the effect of saline degree on the compressive strength of the embedded concrete in the soil. The results of the tested specimens were compared with the reference specimens, i.e. those which had been tested without burying in the soil. The area in which the specimens were buried divided into three zones according to the degree of salinity, this area is in Samawa City (270 km south-west of Baghdad). It was found that the compressive strength of concrete specimens exposed to Sulphate attack in zone A for a period of 79 and 102 decreases from 25.7 MPa to 22.25 MPa, while the others in zones B and C showed a decrease in compressive strength from 25.7 MPa to 17.5 and 18 MPa respectively.

Keywords: Concrete, compressive strength, saline degree, sulphate attack.

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Numerical study to effect of thermal loading on J-integral using finite element method

Muthanna Journal of Engineering and Technology

Volume (2), Issue (2), Year (30 December 2013), Pages (30-47)

DOI:10.52113/3/eng/mjet/2013-02-02/30-47

Research Article By:

Ahmed Razzaq Hassan

Corresponding author E-mail: mr.ahmedrazaq@yahoo.com

ABSTRACT

In this work thermal loading is introduced to the J-Integral calculation using FEM. Study the effect of thermal loadings include temperature difference, convection heat transfer coefficient, temperature of fluid, and thermal conductivity on stresses values and J-integral. Three Programs have been developed, first program is to evaluate temperature distributions in (conduction, convection), while the second program is to compute thermal loading stresses and another loading conditions, third program is to evaluate the J-Integral of opening mode (Mode I) under effect of thermal and mechanical boundary conditions is introduced. So the comparison of the result depends on the validation of the programs developed and the extrapolation methods.

Keywords: J-integral, finite element, stress, displacement.

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Study of the efficiency of reverse osmosis system for water desalination

Muthanna Journal of Engineering and Technology

Volume (2), Issue (2), Year (30 December 2013), Pages (17-29)

DOI:10.52113/3/eng/mjet/2013-02-02/17-29

Research Article By:

Ra’id Tarik Hade and Anas B. Salman

Corresponding author E-mail: dr.raidt @yahoo.com

ABSTRACT

This paper studied the effect of operating parameters on the efficiency of a small scale reverse osmosis with cellulose acetate (CA) membrane type has been studied. different samples were selected from several wells from different spots from Baghdad city. It was found that the highest system’s efficiency can be attained at 36 oC temperature, 250 pressure, pH=3 and 2000 ppm salinity. Also it has been found that the reflux ratio is proportional to the pressure and temperature of feed water, and this ratio is inversely proportional with the pH and salinity of feed water. Four samples with different salinity values were selected from wells in south of Iraq.

Keywords: Reverse osmosis, water desalination.

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A single phase shut active power filter with fuzzy logic based for harmonics minimization under random load variation

Muthanna Journal of Engineering and Technology

Volume (2), Issue (2), Year (30 December 2013), Pages (01-16)

DOI:10.52113/3/eng/mjet/2013-02-02/01-16

Research Article By:

Adel M. Dakhil

Corresponding author E-mail: dr.adelmanaa@yahoo.com

ABSTRACT

In this work a simulation of single phase shunt Active Power Filter (APF) to minimize source current distortion is produced by feeding a nonlinear loads. The simulation results for single phase shunt APF with conventional PI controller and fuzzy PI controller were carried out. These two controller forced the single phase shunt APF to inject equal but opposite current in order to shape the source current to a sinusoidal form in phase with supply voltage. Conventional PI controller meets the required performance for ideal APF, but with unbalance load; this controller is failed to do same job hence the gain values of PI controller are set for a certain load condition. This situation lead to search with fuzzy controller in which the proportional and integral gains adjust dynamically as load condition change. The obtained simulation results for the fuzzy controller show good steady state and transient performance for the plant.

Keywords: Active power filter (APF), conventional PI controller, fuzzy PI controller, harmonics minimization, random load variation.

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Effect of hybrid micro steel-polypropylene fibers on high strength concrete with micro silica fume

Muthanna Journal of Engineering and Technology

Volume (3), Issue (1), Year (30 December 2014), Pages (90-102)

DOI:10.52113/3/eng/mjet/2014-03-01/90-102

Research Article By:

Othman Hameed Zinkaah

Corresponding author E-mail: al_azawy2001@yahoo.com

ABSTRACT

The present investigations consider the effect of hybrid micro steel- polypropylene fibers on high strength concrete. The fractions of steel and polypropylene fibers are 1% and 0.5% by volume respectively. Many mixes have been investigation by combination between steel fibers and polypropylene fibers with different percentages it is (0%S.F-100%P.P.F), (100%S.F- 0%P.P.F), (25%S.F, 75%P.P.F), (50%S.F-50%P.P.F), (75%S.F-25%P.P.F) in addition to reference mix. Properties of high strength concrete such as compressive strength, splitting strength, flexural strength, static modulus of elasticity, and absorption have been studied. The results showed that, the compressive strength decrease by about 28% when adding (0%S.F-100%P.P.F), and there are a small increasing with adding (100%S.F-0%P.P.F). However the results showed that there are an inverse relationship between compressive strength and the amount of polypropylene fibers. Experimental work also showed that adding (0%S.F-100%P.P.F) decrease the splitting strength by about 16%, while using hybrid fibers increase the splitting strength but less than its increasing when adding (100%S.F-0%P.P.F). It can be concluded that, the maximum effect of hybrid fibers is on the flexural strength, it is reach to 128% more than reference mix. Furthermore absorption increases by using polypropylene fibers.

Keywords: Steel fibers, polypropylene fibers, high strength concrete, compressive strength, splitting strength, flexural strength, modulus of elasticity.

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Analytical modeling of eccentrically loaded RC columns confined with FRP

Muthanna Journal of Engineering and Technology

Volume (3), Issue (1), Year (30 December 2014), Pages (75-89)

DOI:10.52113/3/eng/mjet/2014-03-01/75-89

Research Article By:

Nabil M. A. Hussian and Ali M. Lafta

Corresponding author E-mail: abilali75@yahoo.com

ABSTRACT

This paper presents an analytical research on behavior of columns confined with FRP subjected to axial load and uniaxial bending moment, by using finite element method and ANSYS-14. To indicate the accuracy of this program, five reinforced concrete columns strengthened with carbon fibers from the experimental testing of previous researches are reanalyzed by ANSYS program. The results showed that the percentage of experimental ultimate load to analytical ultimate load are (99.4, 99.6, 99.8, 97.5 and 97.2) %, and there is a reasonable agreement between the load-deflection curves for experimental and analytical results for all studied columns. The effects of important parameters on the ultimate load and the ductility of the column are studied. The results showed that the ultimate load and the ductility are increased by 60.3% and 118.8% as the compressive strength increased from 22 MPa to 40Mpa.The study shows, that the increasing in CFRP layers lead to increasing in the ultimate load and the ductility of the column, The maximum increasing in the ultimate load and ductility for the column are 78% and 69.4% respectively. The results showed that ,the ultimate load and the ductility are increased by 24.1% and 23% respectively when the percentage of steel area is increased from 1% to 4%. Finally, loads with several eccentricities from the center of the column are studied, the results show a significant reduced value in the ultimate load for confined column by 51% at load eccentricity value equal to 125mm. While the column ductility reduced to 42% for the same load eccentricity.

Keywords: Column, CFRP, strengthen, eccentrically load, FEF, ANSYS-14.

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Experimental study for the size effect on the flexural behaviour of SPLWA reinforced concrete slabs strengthened with CFRP strips

Muthanna Journal of Engineering and Technology

Volume (3), Issue (1), Year (30 December 2014), Pages (60-74)

DOI:10.52113/3/eng/mjet/2014-03-01/60-74

Research Article By:

Readh A. Abbas and Ahad Z. Hamoodi

Corresponding author E-mail: readh_56@yahoo.com

ABSTRACT

An experimental Study was conducted to investigate the size effect on the flexural behaviour of sand-porcelinite lightweight aggregate reinforced concrete one way slabs (SPLWAC OWS). In order to get a clear results, eight slabs were casted, and six of them were strengthened with carbon fibre reinforced polymer (CFRP) strips. To investigate the size effect, four slabs were of 300 mm width, 1500 mm length and 80 mm depth and the others were of 300 mm width, 2000 mm length and 108 mm depth. The present study showed that the SPLWAC OWS showed a reverse size effect. The failure mode was by yield of steel for the control un-strengthened slabs, while it was by yield of steel followed by rupture of CFRP strips for the strengthened slabs. Also, the results of this study were compared with those obtained by the ACI equations. This comparison showed that the ultimate moment strength and deflection obtained by the ACI equations were always less than those obtained experimentally.

Keywords: Carbon fiber reinforced polymer strips, sand-porcelinite lightweight aggregate concrete, one way slabs, monotonic loading, variable amplitude loading.

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Experimental and numerical investigation of I-section lightweight concrete deep beams strengthened with CFRP failing in shear

Muthanna Journal of Engineering and Technology

Volume (3), Issue (1), Year (30 December 2014), Pages (46-59)

DOI:10.52113/3/eng/mjet/2014-03-01/46-59

Research Article By:

Riadh A. Abass and Mustafa Sh. Zewair

Corresponding author E-mail: readh_56@yahoo.com

ABSTRACT

The experimental program consisted of testing four I-section reinforced concrete deep beams strengthened with CFRP strips made from lightweight concrete (porcilinate). The experimental program variables include configurations of CFRP. Experimental results obtained from the adopted strengthening CFRP techniques show a significant improvement in the behavior and shear carrying capacity of reinforced concrete deep beams. A stiffer load deflection response is observed for beams strengthened with CFRP strips as compared with response of control deep beam and the inclined CFRP strips give better enhancement than the vertical CFRP strips in ultimate load, deflection and crack width. Nonlinear finite element analysis is performed using the ANSYS-11. The Comparison between experimental results and numerical results indicates that numerical models can successfully used to simulate similar cases. Where the ultimate numerical load to ultimate experimental load ranged between (88%-96%). And good agreement for (load–deflection) curves between numerical and experimental.

Keywords: ANSYS, CFRP, I-section, lightweight, strengthened.

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Effect of magnesium powder addition on some mechanical properties of composite glass-ceramic materials

Muthanna Journal of Engineering and Technology

Volume (3), Issue (1), Year (30 December 2014), Pages (38-45)

DOI:10.52113/3/eng/mjet/2014-03-01/38-45

Research Article By:

Ali Husain Hawi

Corresponding author E-mail: hawy63@yahoo.com

ABSTRACT

Glass – ceramic material as main component in aerospace application (shuttle), bio-material for the veneering of metal restoration in destroy. In this work glass-ceramic from raw material (Oxides + BaO) was prepared. The XRD analysis showed that the heat treatment causes a very rapid crystallization process and at 900 °C, a new phase, MgFe2O4 structure appears in the glass matrix. Addition of different weight percentage of Magnesium metal to glass – ceramic were studied to estimate some properties such as density , young modulus, and hardness. The results show decreasing in density to 2.06*103kg/m3 when add 9%Mg , this result prefer in application of glass-ceramic, especially in aerospace application (window of shuttle). The addition of 9% Mg leads to increase young modulus (E) to (73.5 Gpa). Mg addition on glass -Ceramic leads to decrease Hardness to (260.5 HB at 9% Mg). Microstructure inspection show the gradually spread of Mg metal through the glass matrix leading to a consolidate for all the alternative properties.

Keyword: Addition of Mg, glass ceramic, density, mechanical properties.

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Deriving rainfall intensity-duration-frequency relationships for Kerbala city

Muthanna Journal of Engineering and Technology

Volume (3), Issue (1), Year (30 December 2014), Pages (25-37)

DOI:10.52113/3/eng/mjet/2014-03-01/25-37

Research Article By:

Ayad Kadhum Hussein

Corresponding author E-mail: dr.ayad.alkafajy@gmail.com

ABSTRACT

Intensity-Duration-Frequency (IDF) relationship of rainfall amount is one of the most commonly used tools in water resources engineering for planning designing, and operation of water resources projects. The objective of this research is therefore, to develop operational IDF relationships for the province of Kerbala based on historical data. The IDF curves have been developed considering application to Kerbala area and presented in the form of general mathematical equation, curves relating Intensity–Duration-Frequency of rainfall. The IDF curves are plotted for 2, 5, 10, 25, 50 and 100-year return periods in Kerbala. The values of the constants α, γ and exponents β, τ in the IDF function are calculated from the observed precipitation data by using different methods. Using the methods of goodness of fit has been reached in Kerbala that the Log Pearson type III is the best method of other methods.

Keywords: Plotting position, rainfall frequency analysis.

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The ultimate strength of double short composite columns under concentric loads

Muthanna Journal of Engineering and Technology

Volume (3), Issue (1), Year (30 December 2014), Pages (11-24)

DOI:10.52113/3/eng/mjet/2014-03-01/11-24

Research Article By:

Ragheed Fatehi Makki

Corresponding author E-mail: ragheed.almutwali@uokufa.edu.iq

ABSTRACT

No-Fine concrete filled double steel tube columns (CFDST) are being increasingly used for structural applications. It has been used for submerged tube tunnels, nuclear containment, liquid and gas retaining structures, vessels under external pressure in very deep water and for compression members in offshore construction, this is due to the aesthetic appearance, ease of maintenance and simple of construction. The (CFDST) columns also have excellent resistance to seismic loads and fire. This paper comprises of an experimental study on the structural behavior of double steel tubular columns filled with No-Fine concrete under axial load. Eight samples of double steel circular tubes with different diameters for the inner and outer tubes are used, with different slenderness ratios (L/r), different ultimate strengths of No-Fine concrete (fc′). Also two cases are study for (CFDST) samples first with hollow inner tube and second with completely filled inner and outer tubes with No-Fine concrete.
The experimental results show that the effect of height (the slenderness (L/r) ratio) on the ultimate strength of CFDST columns will have a reverse relation. While the effect of uniaxial compressive strength (fc′) and the effect of fully filling the core of internal tube on the ultimate strength of CFDST columns will have an increase relation.

Keywords: No-fine concrete, compression members, concrete filled double steel tubes (CFDST).

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Statistical analysis of quality parameters of Maamera sewage treatment plant

Muthanna Journal of Engineering and Technology

Volume (3), Issue (1), Year (30 December 2014), Pages (01-10)

DOI:10.52113/3/eng/mjet/2014-03-01/01-10

Research Article By:

Nabaa Shakir Hadi

Corresponding author E-mail: nabaalshimmri@yahoo.com

ABSTRACT

The present study aimed to statistical analysis of quality parameters of Maamera sewage treatment plant at Hilla city. The plant designed to serve 50000 populations and it is operating on biological treatment method (Activated Sludge Process) with an average wastewater inflow of 12000 M3D. Wastewater data were collected yearly by Mayoralty of Hilla from the influent and effluent in Maamera Sewage treatment plant for major water quality parameters, such as biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), pH, T, chloride (Cl) over a period of six consecutive years. performance efficiency of the plant has been estimated for each year. A multivariate statistical technique of the data has been attempted by applying Cluster analysis using Statistical Package for Social Sciences (SPSS). The result reveals that the overall performance of the existing was satisfactory. Cluster analysis shows that years ( 2009, 2010 , 2011 and 2012) indicate a good level of treatment compared to that compared to that of 2007 and 2008. Final effluent quality (in term of mean value of six consecutive years) does not meet the stringent regulations proposed by the Iraqi National Standards set by the Regulation 25 of 1967. The BOD5/COD ratio of the influent was calculated as 0.49 in total wastewater.

Keywords: Maamera sewage treatment plant, cluster analysis, statistical analysis.

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Assessment of natural radioactivity levels and radiation hazards for building materials used in some selected provinces in Iraq

Muthanna Journal of Engineering and Technology

Volume (3), Issue (2), Year (30 December 2015), Pages (80-84)

DOI:10.52113/3/eng/mjet/2015-03-02/80-84

Research Article By:

Muhannad Kh. Mohammed

Corresponding author E-mail: muhannad62@yahoo.com

ABSTRACT

The radioactive properties of building materials used for the construction of habitable structures in Iraq were investigated in this study. In the framework of this paper, ten samples of commonly used building materials (bricks and rocks used for incasing) were collected from ten Iraqi provinces for radiometric analysis. The activity concentrations of natural radionuclides in the selected samples were determined by gamma ray spectrometry using sodium iodide (NaI) detector. Based on the results of this study, the use of rocks for incasing manufactured in Al-Rumadi is considered to be unsafe for human habitation from radiological points of view due to relatively high background radioactivity. The radioactivity levels for building materials for the remaining investigated areas were well within the permissible limits.

Keywords: Natural radioactivity levels, radiation hazards, building materials.

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Structural behavior of self compacting concrete

Muthanna Journal of Engineering and Technology

Volume (3), Issue (2), Year (30 December 2015), Pages (69-79)

DOI:10.52113/3/eng/mjet/2015-03-02/69-79

Research Article By:

Jamal Abdul-Samad Khudair and Aqeel Hatem Chkheiwer

Corresponding author E-mail: aqeelcivil@yahoo.com

ABSTRACT

This study investigated the influence of type of concrete (self compacting concrete (SCC) and normal concrete (NC)) and compressive strength (30, 50 and 62 MPa) on the flexural and shear behavior of reinforced concrete beams, as well as punching shear of slabs. To achieve these targets, 18 beams and 6 slabs are equipped, tested and assessed. The tested beams were divided into three groups, the first group consists of six beams failed in flexure, the second group contains six beams without web reinforcement failed in shear with shear span/depth ratios of 3 (slender beams), the third group consists of six beams without web reinforcement failed in shear with shear span/depth ratio of 1 (deep beams), each group consisted of three SCC and three NC geometrically similar rectangular beams of different concrete strengths. Test results indicated that, for beams failing in flexure, SCC beams showed similar ultimate load to NC beams. For slender beams failing in shear, the ultimate load for beams with fc’ of about 32 and 48 MPa, NC beams showed 6.75 % higher ultimate load compared with SCC beams, but beams with fc’ of about 62 MPa, SCC and NC beams showed almost the same ultimate load value. For deep beams, no considerable difference in ultimate loads for SCC and NC beams was noticed. For the six geometrically similar slabs (three slabs made with SCC and three slabs made with NC of different concrete strengths) which were designed to fail in punching shear, it was found that, SCC slabs exhibited 17.25 % higher ultimate punching shear load than NC slabs.

Keywords: Self-compacting concrete, structural behavior, flexure, shear, punching shear.

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Punching shear resistance of lightweight concrete two way slabs strengthened with CFRP strips

Muthanna Journal of Engineering and Technology

Volume (3), Issue (2), Year (30 December 2015), Pages (58-68)

DOI:10.52113/3/eng/mjet/2015-03-02/58-68

Research Article By:

Mazen D.Abdulah

Corresponding author E-mail: mazend_81@yahoo.com

ABSTRACT

The aim of this study is to investigate the experimental behavior of reinforced concrete light weight concrete two-way slabs stiffened by CFRP strips to punching load and compare the results with the finite element model results. The experimental program includes testing a total of 14 slabs (800 x 800 x 70) and (800 x 800 x 90) mm. The slabs are divided into two groups; each group consists of seven slabs. In each group of seven slabs, one slab was left without strengthening as a reference slab, while each slab of the remaining six slabs has a different CFRP distribution. The effect thickness of slabs and shape of the CFRP distribution on the punching shear strength of slabs are studied. All slabs in this study are designed to fail in punching shear. During the test, the slabs are simply supported on all four edges and loaded centrally by a (75 x 75) mm column. Load deflection curves, cracking patterns and effect of variables on the test results are discussed. Experimental results showed that, the CFRP strengthening increased the ultimate punching load of the slabs by (9-26) %, also the first cracking load increased by (38-141) %. The strengthened slabs showed less deflection during loading by about 24% compared to the non- strengthened slabs. Increasing the slab depth gives changes to the slabs punching strength. The slabs are modeled by three dimension finite elements and non-linearly analyzed by the ANSYS program where the concrete is represented by the eight nodes solid element (solid 65) and the CFRP strips are represented by (3D shell 41) with a perfect bond between the CFRP and concrete slabs. Finite elements results showed a comparable results to laboratory tested slabs and the difference is not more 12% in ultimate load.

Keywords: CFRP, solid 65.

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