Basrah Journal for Engineering Sciences

The paper deals with neural networks identification of ultimate moment capacity of steel-concrete composite beams on base of experimental results. Basic information on artificial neural networks and its parameters suitable for analysis of experimental results are given. Two types of neural network algorithms are used. Results of identification are reported. The results show that artificial neural networks are highly suitable for assessing the ultimate moment capacity of composite section. The proposed neural network was also used to explore the effect of the various parameters on the behaviour of composite beams.

The study investigates the behaviour of reinforced concrete corner joints under monotonically increasing loads which tend to increase the right angle between the two joint members. The experimental results for two case studies are considered, and the ANSYS computer code is employed to create three-dimensional models for corner joints within the context of the finite element method. The effect of reinforcement details at the corner joint is studied for commonly used detailing systems, and the nonlinear response is traced throughout the entire load range up to failure. The results obtained are generally in good agreement with the experiments, and show that the detailing system has a significant effect on corner joint behaviour, with efficiencies ranging from as low as 54% up to 147%.

The principle aim of this research is concentrated to analyze the effect of cracks and their propagations on the mechanical behavior of a quasi-brittle material such as concrete. The singularity (stress concentration to infinity at the tip of crack) is avoided by using the principal of fracture energy with the fictitious crack approach. The concrete crack is divided into two major zones; the first one is the fracture zone (a combination of bridging effect and the cohesive microscopic cracking) which obeys a special law permitting the transmission of stress across the two faces of crack, this zone is considered as partially cracked concrete. When the opening of the crack exceeds a specific value, this zone is converted to a real crack (an open crack) and cannot transmit any stress across the two faces of a crack. The program of finite element used in this research is prepared by the researcher using discrete-crack approach with the experimental data obtained from the flexural test on notched beam loaded under three-point bending, where fracture mode I is dominated. The response of the applied load-crack mouth opening displacement (CMOD) with appropriate fracture energy is selected. The results show that the cohesive microscopic cracking zone for the plain concrete is very wide. The cohesive stress distributions across the microcracks with the corresponding crack openings are drawn from the first crack appearance till the beam failure.

Shatt Al Arab River is the main water source for all water treatment plants in Basrah governorate. In order to assess its suitability as a source for domestic water supply and the performance of some of main water treatment plants, water quality index (WQI) is obtained for both raw and treated water for 10 water treatment plants. Physic-chemical parameters were monitored for the calculation of WQI for Winter, Spring, Summer, and Autumn seasons from March- 2011 to March- 2012.The parameter which were taken into account for the present work are pH, turbidity, electric conductivity, total alkalinity, total hardness, Ca, Mg, Cl, SO4, TDS, Na, and K. The results indicate that Shatt Al Arab is very poor for domestic, industrial, and irrigation purposes during Winter, Spring, Summer, and Autumn seasons, while seven of ten of consider of water treatment plants produce water of poor quality.

A linked simulation-optimization model for obtaining the optimum management of groundwater flow is presented in this research. (MODFLOW, 98) packages are used to simulate the flow of the groundwater system. This model is integrated with an optimization model which is based on the genetic algorithm (GA). Three management cases were undertaken by running the model with adopted calibrated parameters. In the first case found the optimum value of the objective function is (0.32947E+08 m3/year), in other words, the pumping rates could be raised to nine times the current pumping rates, with a highest decline in the hydraulic heads of groundwater compared with initial hydraulic heads reached to 6 cm. In a second case twenty six wells out of thirty five can be operated with "on/off" status associated with each well to obtain the maximum value of pumping rate. In third case is allowed to move a location of well anywhere within a user defined region of the model grid until the optimal location is reached. The optimum value of objective function in third case is (0.35539E+08 m3/year) with 8% increasing of the pumping rates compared with the first case. This is due to the random distribution of existing well locations.

Polyethylene terephthalate (PET) was prepared from (PET) flakes and 25% of NaOH solution were added to in tri-neck flask, the reaction run for six hours at temperature (100-130) oC and the precipitate was reacted with ethylene glycol at temperature (130-160) oC. IR spectrophotometer was used for the diagnoses of (PET). Differential scanning calorimeter (DSC) is used to indicate glass transition temperature Tg, the melting temperature Tm and the heat absorbed. Part hundred ratios (phr,s) of (PET) rather than dosage of PET in gms. To concrete cubes were added to study its effect on concrete properties. Additives of (phr,s) impart performance such as increased cement dispersion, and enhance the performance of concrete which was appeared in maintaining a lengthening or slow the setting time that meets product and job needs. Maximum and minimum compressive strength is 43.7 MPa and 30.0 MPa at 0.3 gm. and 0.1 gm. respectively.

The foundation of soil is considered safe when the factor of safety against shear failure is adequate and the settlement of the foundation should be tolerable and does not cause any unacceptable damage for the structure. The ultimate bearing capacity is defined as the maximum pressure which may be applied to the soil without causing neither a shear failure nor large settlement. In this research the bearing capacity of the soil at diesel power plant project in Al-Diwaniyah city by plate bearing test. The soil has been tested in the field in the locations of four foundations for circular tanks of diameter of 17m. The load is applied to the plate in four increments. In each increment; the load stays static for 15 minutes according to ASTM D1194-94 specification. The results showed that the plate settlements of the soil under three tanks were within the permitted settlement. The allowable bearing capacity of soils under these tanks were (117, 137 and 137) kPa respectively. While, the soil under the fourth tank was soft and the plate settled approximately 30 mm immediately after applying the first increment of load. Therefore the soil is considered improper and recommendations are suggested to improve it.

New illustration for mixed mode fracture mechanics analysis of central cracked plates using crack extension technique and Matlab Environment is presented. The technique of crack extension is applied to the computation of mixed mode stress intensity factors in linear elastic fracture mechanics for these plates for different loads. The technique uses the Brown approximate solutions for stress intensity factors and the Westergaard analytical solutions for stress and displacement near a crack tip in finite plate to calculate crack extension during each load step using an
proved to be a good tool for computation and results illustration for mixed mode stress intensity factors. The results were illustrated in a new form which is convenient for engineers and fracture mechanics analyst. The developed procedure reduced the need for sophisticated numerical analyses, which require more time and effort, to calculate the same parameters tackled in this research.

The conjugate natural convection-conduction heat transfer in a domain composed of nanofluids filled porous cavity heated by a vertical solid wall is studied under steady-state conditions. The vertical left wall of the solid is kept isothermal at hot temperature Th. The vertical right wall of the solid is in contact with the nanofluid saturated porous medium contained in the cavity. The right vertical wall of the cavity is kept isothermally at the lower temperature Tc. The upper and lower horizontal walls are kept adiabatic. The governing equations of the heat transfer in the solid wall and heat and nanofluid flow, based on the Darcy model, in the nanofluid-saturated porous medium together with the derived relation of the interface temperature are solved numerically using the over-successive relaxation finite-difference method. A temperature independent nanofluids properties model is adopted. The investigated parameters are the nanoparticles volume fraction  (0-0.2), Rayleigh number Ra (10-1000), solid wall to base-fluid saturated porous medium thermal conductivity ratio kwf (0.1, 1, 10), and the solid wall thickness D (0.05-0.5). The results are presented in the conventional form; contours of streamlines and isotherms and the average Nusselt number. At a very low Rayleigh number Ra=10, an enhancement in heat transfer within the porous cavity with  is observed. Otherwise, the heat transfer may be unchanged or deteriorated with 
depending on the wall thickness D and the conductivity ratio kwf.

Water pollution is the most important tasks facing all countries in the world to obtain suitable water for municipal, industrial, and agricultural uses. This study concerns with the effect of Bagdad city waste water on pollution and quality of Tigris River water using index of Aquifer water quality (IAWQ). The accuracy of chemical analyses of the selected water samples are conduced according to world standards of health classifications. Results of these analysis show that only two types of the 13th tested sample are ( certain ) ,while the other patterns ( models )are of the ( probable certain ). Cluster analysis is applied to evaluate the studied water characteristic. The results of the cluster analysis show the presence of three varying groups in their impact on their chemical properties on water .According to the cluster analysis and permissible limits of the variables, three chemical variables cadmium, lead, and calcium are selected to indicate its impact on the studied area. It is found that when using (IAWG) for the Tigris River, there is an increase in the values of the index along the river from its entry to Baghdad until it meets the Diyala river, showing a clear pollution of the Tigris river water.