Print ISSN: 1813-0526

Online ISSN: 2220-1270

Volume 17, Issue 4

Volume 17, Issue 4, Summer and Autumn 2009, Page 1-96

Flexural Behavior Of Flat And Folded Ferrocement Panels

Sura A. Majeed; Mohamad N. Mahmood

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 1-11
DOI: 10.33899/rengj.2009.43268

The present paper describes the results of testing folded and flat ferrocement panels reinforced with different number of wire mesh layers. The main objective of these experimental tests is to study the effect of using different numbers of wire mesh layers on the flexural strength of folded and flat ferrocement panels and to compare the effect of varying the number of wire mesh layers on the ductility and the ultimate strength of these types of ferrocement structure. Seven ferrocement elements were constructed and tested each having (600x380mm) horizontal projection and 20mm thick, consisting of four flat panels and three folded panels. The used number of wire mesh layers is one, two and three layers. The experimental results show that flexural strength of the folded panels increased by 37% and 90% for panels having 2 and 3 wire mesh layers respectively, compared with that having single layer, while for flat panel the increase in flexural strength compared with panel of plan mortar is 4.5%, 65% and 68% for panels having 1, 2 and 3 wire mesh layers respectively. The strength capacity of the folded panels, having the particular geometry used in the present study, is in the order of 3.5 to 5 times that of the corresponding flat panels having the same number of wire mesh layers. Both types are also analyzed using finite element method to check the flexural stresses in these panels under self weight and cracking load.

Keywords: Ferrocement, Flat Panel, Folded panel, Mortar, Wire Mesh.

Free Vibration Analysis Of Curved Box Girder Bridges by Higher Order Finite Strip

Zeena A. Mohamma; Ayad A. Abdul Razzak

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 1-16
DOI: 10.33899/rengj.2009.43291

A higher-order conical frustum shell strip for analysis of free vibration of curved box girder bridges is developed, the auxiliary nodal line technique is used in the formation, the application of the motion equation by form the matrices of the stiffness and that of the consist mass of the strip and which has been mathematically derived by solving sixth and third order equations for bending and in plane actions respectively. Guyan reduction technique have been applied for each stiffness and the mass matrices of bridge. The strip which implies minimizing the degrees of freedom of the auxiliary nodal line of the Higher Order Finite Strip in order to reduce the size of the matrix from (15x15) to (8 x 8).
The study has come out with very good results compared to the previous studies in terms of the natural frequencies for the first harmonic number of the box girder bridge section which is composed of two box cells with inclined webs. The ratio of difference between the present and previous studies have reached (6.73%) , while the natural frequencies for the seconed harmonic number of the same box section the ratio is about equal (3.765%) .

Keywords: Box Girder Bridges, Free Vibration Analysis, Higher Order Finite Strip.

Prediction Of Ultimate Load Capacity Of High-Strength Reinforced Concrete Corbels

Ali Ramadhan Yousif

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 12-27
DOI: 10.33899/rengj.2009.43273

A study on the behavior of reinforced high-strength concrete corbels is carried out using nonlinear finite element analysis and a simplified softened strut-and-tie model. In the numerical analysis, eight-node isoparametric plane stress elements are employed to model the concrete material. An elastic-strain hardening plasticity approach combined with cracking damage is used in modeling the concrete behavior. The reinforcing bars are treated as embedded elements and are considered as elastic-perfectly plastic material. In the analytical method, the analysis is based on truss analogy following the provisions of Appendix A of the ACI 318-05 Code. Strength predictions of both methods correlate well with the 34 test results of corbels available from the literature. It was concluded that the adopted finite element model is a powerful tool for the analysis of such disturbed region. Also the simple truss model used proved to be a suitable design tool for these members. The finite element method can be used in conjunction with the truss analogy for optimum design.

Keywords: corbels; deep beams; finite element; non-flexural members; plasticity; shear strength; strut-and-tie models.

Effect Of Externally Bonded Gfrp Sheets On The Shear Transfer Capacity Of Concrete

Ashtar S. Al-Luhybi; Bayar J. Al-Sulayfani

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 17-27
DOI: 10.33899/rengj.2009.43293

The current research includes practical results of study and investigated the subject of strengthening the shear strength through uniaxial confinement (one direction) using GFRP Sheets. This study was carried out by casting eight specimens (the push-off specimens group) which was divided in to four groups, the first non confined, being the reference group, the remaining groups consisted of two specimens each with only one variable being the degree of strengthening that is the numbers of confinement layers. The second, third, and fourth group were confined with one, tow, and three layers respectively. All specimens were tested through the application of a vertical load up to failure. The result indicated that there is a clear indication of shear strength increase amounting to 33% relative to the reference specimens (non confined), also there was a noticeable increase in the absorption capacity as a function of the number of confinement layers.
Key words: Strengthening, Shear Transfer on concrete, GFRP Sheets, Push-off specimens.

Modeling and Computer Simulation of a Dual Converter System

Yasser Ahmed Mahmood; Dhaiya Ali Al-Nimma

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 28-35
DOI: 10.33899/rengj.2009.43294


DC Drives have been used and still being used in many industrial applications as adjustable speed drives. Among these applications are robotics, mill, steel, cement…etc, [1] industries. The dual converters are the most common power electronics equipments that are used in driving DC motors. Each converter drives the motor in two different quadrants in the torque-speed diagram, thus the drive system becomes a four-quadrant. Computer Simulation results has been obtained for the steady state condition. The results are in the form of motor and converters currents and voltages for different trigger angles. In order to validate the simulated results, practical results have been obtained for the same triggering angles. For dynamic conditions such as starting condition have been obtained practically and compared with the simulated results, be sides that studying some abnormal conditions such as fault condition with in the motor or in the dual converter.

Key words: DC drives, simulation of DC drive, dual converter.

Effect of Elevated Temperature on Some Properties of Air-Entrained Steel Fibers Reinforced Concrete

Rana Burhan Abdurrahman; Abdul Hakeem Hamed Ahmad

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 28-41
DOI: 10.33899/rengj.2009.43276

In this paper, an experimental investigation was conducted to explore the mechanical properties of air entrained steel fibers reinforced concrete (AESFC). The residual mechanical properties measured include compressive and splitting tensile strengths, modulus of elasticity and (stress – strain) curves. Air-entrained concretes (AECs) were prepared with different steel fibers content (0, 0.4, 0.8, and 1.2) % added to enhance the strength of concrete. After exposure to high temperature included (200, 400, 600) ◦C, the residual mechanical properties of AESFC were investigated and compared with normal concrete. Test results showed reduction in properties by different ratio for all types of concrete after exposure to elevated temperature, the tensile strength and elastic modulus deteriorated with temperature more than the compressive strength. Using steel fibers seems effective in minimizing the degradation of strength for the concrete. Results showed also that the decrease in compressive strength after exposure to high temperature could be reduced by increasing volume of samples. Heating accompanied with weight losses and color changes became clearer at (400 – 600) ◦C exposure.
Key words: Air entrained concrete; steel fibers ; elevated temperature

Improved Equations for Estimating Spray Losses of Fixed Sprinkler Irrigation Systems in Iraq

Nawal M. Jajoo

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 36-41
DOI: 10.33899/rengj.2009.43298

Many local field studies on sprinkler spray losses in Iraq have been conducted, the first was in 1980 and the latest is in 2008. Many equations to estimate these losses have been proposed. But, most of these studies depended on narrow ranges in the values of the parameters and variables involved. Therefore, there may be great risk in applying these equations in the design and management of sprinkler irrigation systems. Add to that, the problem of unavailability of data for some of the variables involved which makes the use of these equations impossible. Thus, this study presented a group of 14 prediction equations for the sprinkler spray losses, so that it becomes possible to estimate these losses if one or more of the following main variables is available: air temperature, wind speed, relative humidity, nozzle size, and operating pressure head. The derivation of the proposed equations depends on all available local field data, thus making these equations more accurate and general.

Key words: Sprinkler irrigation, sprinkler spray losses, sprinkler irrigation in Iraq.

Validation Of The Total Resistance Heat Dissipation Model For Heat Transmission Through Annular Fins With Variable Heat Transfer Coefficient

Ghalib Y.Kahwaji; Ziad M. Al-Makhyoul

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 42-50
DOI: 10.33899/rengj.2009.43280

The present paper includes analytical investigation of the validity of total resistance heat dissipation model using variable heat transfer coefficient for annular fins constant thickness. The model is given as:
Furthermore, a finite difference method using SOR technique is devised to serve the two purposes of verifying the two dimensional heat transfer model and to cover a wide range of fin parameters and heat transfer coefficient models. The results were in agreement and proved the validity of the suggestion model under the both the constant and variable heat transfer coefficient assumptions.
Key words: Total resistance, Variable heat transfer coefficient, Heat transfer, Annular fins

Laboratory Study of Flow Energy Dissipation Using Stepped Weirs

Azza Nasiralla AL-Talib; Hana Abd AL-Majeed Hayawi

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 42-51
DOI: 10.33899/rengj.2009.43300

A laboratory study was conducted on stepped and unstepped weirs in order to find their efficiency of dissipating flow energy. Thirty six weirs were constructed and tested to compare between stepped and unstepped weirs in flow energy dissipation, twenty seven of them were stepped while the rest were unstepped. Three heights of stepped weirs (P=36,45,54)cm were used with different numbers of steps (n=9,12,15) , and three downstream slopes of stepped face (h/l=1/2,1/3,1/4) were tested, while for unstepped weirs one height of weir (P=54)cm and three downstream slops (α=26.6o,18.4o,14o) were tested. The results showed that increasing height of weir and decreasing both number of steps and downstream slops stepped face of the weir will cause an increase of the ratio of flow energy dissipation, and the stepped weirs are more efficient in flow energy dissipation compared with unstepped weirs. The percentage of flow energy dissipation (E%) is increased by increasing the ratio of height of weir to critical water depth (P/dc), the ratio of length of the step to critical water depth (l/dc) and the ratio of height of step to critical water depth (h/dc) while it decreases by increasing the discharge (Q). Imperical relationships between the ratio of flow energy dissipation and factors affecting it were obtained in stepped weirs.

Numerical Study of Natural Convection Heat Transfer of a Square Eccentric Body Buried in a Porous Media

Ramiz Ibraheem saeed; ed Ahmed Ali

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 51-62
DOI: 10.33899/rengj.2009.43283


Natural convection in a saturated porous medium bounded by two horizontal eccentric ducts is studied numerically by solving the governing Darcy-Boussinsq equations using finite differences on very fine grid. This paper reports the effect of the position of a cooled square body with respect to the centre of the square cavity vertically and horizontally. The numerical results of heat transfer are presented for modified Rayleigh number Ra* (based on width of cavity) in the range (50 to 400) and for different size of the body with respect to the width of the cavity (0.25x0.25,0.3x0.3,0.5x0.5) and six positions of the body respect to the center of cavity. The results are represented by streamlines and isotherms to show the behavior of the flow and temperatures distribution. Also some graphics had been obtained which represent the relationship between Nusselt and Rayleigh numbers with eccentricity. (Key words: natural convection, porous medium, cavity)
Key Words : Porous medium , Thermal nonequilibrium , Heat transfer , Natural convection.

The alteration of designer logical performance during architectural design task

Uriya Noory Saeed; Nahith Taha Abdulla

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 52-66
DOI: 10.33899/rengj.2009.43304

Although many studies have tried to reduce differences between conceptual models of thinking processes, through the description of the operational performance of any intellectual task includes problem solving, however, because of the design specificity in this regard, and diversity of its motion, there were always, many of obstacles that stand in the way of developing a model describes the operations of reasoning achievement during different architectural design phases. The need for explicit language of designer thinking, and architects performance or how they underlined such aspects, was incentive concern for many contemporary studies, which tried to cover this area in one way or another. This research tries to investigated designer logical behavior during a design process, through the review of inference acts, during conceptual stage of that process, also it tries to investigate the nature of the mobility of this behavior across time of the task.

Keywords: Logic, Logical Structure, Architectural Inference, Architectural Design

FPGA Implementation of Adaptive Noise Canceller

Aws Hazim saber; Rafid Ahmed Khalil

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 63-72
DOI: 10.33899/rengj.2009.43287

This paper presents hardware implementation of least mean square (LMS) adaptive filter based Adaptive Noise Canceller (ANC) structure on FPGA using VHDL hardware description language. First, the adaptive parameters are obtained by simulating ANC on MATLAB. Second, the data, processed by FPGA, such as step size, input and output signals, desired signal, and coefficients of ANC, are exactly expressed into fixed-point data representation. Finally, the functions of FPGA-based system structure for such LMS algorithm in time sequence are synthesized, simulated, and implemented on Xilinx XC3S500E FPGA using Xilinx ISE 9.2i developing tool. The research results show that it is feasible to implement, on chip train, and use adaptive LMS filter based ANC in a single FPGA chip.
Keywords: Adaptive noise canceller, least mean square, FPGA, Adaptive FIR filter

Spatial and Visual Organization Properties of Mosul University Components

Miqdam A. M. Alkurukchi

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 67-79
DOI: 10.33899/rengj.2009.43305

Spatial organization is the operative mean through which built environment expresses the Purposes of its creation.
Due to its ability to provide basic requisites of movement, encounter and avoidance patterns, Modern Studies assume Spatial Organization as the main generator of Social life.
Syntactical relations of Spatial and Visual organization for Mosul University Campus components, represents phenomena that lacks adequate research endeavors, despite its importance as a social organization phase, and a human mode of reaction. Accordingly, this paper aims to explain these relations.
Using Space Syntax methodology, a number of findings were obtained, explaining Spatial and Visual properties of Mosul University Campus components.

Fuzzy Self Tuning Of Dc Position Control Based On Labview

Sura Nawfal Abd Alrazaaq; Fakhraldeen Hamid Ali

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 73-83
DOI: 10.33899/rengj.2009.43288

This paper investigates the effect of quantization gain factors, at the input side, and the scaling gain, at the output side, of a fuzzy controller. A fuzzy control system is designed with two main parts: a basic fuzzy controller (BFC) which produces the output control signal and supervisor fuzzy controllers (SFCs) to continuously adjust, on-line, the I/O scaling or gain factors of the (BFC) in order to improve its performance against different dynamic operating conditions. The designed self tuning controller is used to position control of a DC motor with un known parameters according to the feed back inputs, a tracking error (e) and change of error (Δe), based on the proposed fuzzy rules. The system implementation and tests are carried out using LabVIEW software ( V8.2 ) with a data acquisition card type (NI PCI-6251) from National Semiconductors to achieve real time measurements.

Keywords: self-tuning, fuzzy controller, position control, scaling gain, LabVIEW .

The Formal Composition of Khans in Islamic Architecture (An Analytical Study)

Assda A. H. Al-Tuhafi; Talaat I. M. Al-Aane; Khawla F. M. Al-Daudi

AL-Rafdain Engineering Journal (AREJ), Volume 17, Issue 4, Pages 80-96
DOI: 10.33899/rengj.2009.43312

Islamic architecture is considered to be a unique example that reflects the impact of structural formation systems in establishing its form; the structural relations represent the most important items and bases of architectural structures, especially at the abstract level. The structural relations form the basic foundation which represent the most important aspect in producing the formal structure of any building thus they are considered to be the most important method in describing the physical reality of architectural production . Stemming from the above fact, the study focuses on the structural relations that form the plans. The problem of the study is that structural relations which form the plans of Khans buildings in Islamic architecture are not clear. The aim of the present study is to clarify the specialty of Muslim architect intellectuality in the formation of a particular mechanism or method to form and design studied plans with specific functions like khans. To achieve the aim of the study a theoretical framework of structural relations is built depending on modern studies on formation of those relations on the bases of the statistical analytical method. The results arrived at show that the structural relations which form and construct the plans of Khans buildings are characterized by uniqueness as a distinguishing character of Islamic architecture some of these types of building are the khans, though they differ in their architectural design, their date and ever their geographical location. This in turn gives an indication and proof of the Muslim architect creative role in determine the distinguished identity of his architecture with the incentive of Islamic cultural intellect held by that architect all over the places of his civilization whenever and wherever he exists.
Key Word : Formal Composition , Relationships Formative , Khan , Islamic architecture