KUFA JOURNAL OF ENGINEERING

This paper performed two steps of analysis. The first step used Soil Conservation Service (SCS) method to estimate surface water infiltration rates from the earth fill dams (proposed Kashkan dam north of Duhuk city as a case study). In the second step, a two dimensional finite element seepage analysis using (Seep/w) software was employed to determine seepage rates. The main purpose of constructing Kashkan dam is to store the rainfall water during rainy season and use it during summer season to provide the human requirements of water as well as to performed the agricultural requirements. Mean monthly rainfall data recorded for selected watersheds during the period (1986-2008) was used. The maximum infiltration rate during the depended period asymptotically tends to the value of the saturated permeability. The computed infiltration rates were used as input data for the seepage analysis by assigning the ground surface boundary condition. Finally, positive and negative pore water pressure distributions obtained

The influence of salt layer contamination of thickness below (2 mm) on solar evacuated tubes water heater performance parameters was investigated experimentally in several operating weather conditions on October and November 2011 at Baghdad location taking into consideration the effect of ambient conditions and collector inclination angle. It was concluded that the salt thickness have a minor effect on the collector efficiency, water circulation in the tubes and the heat loss coefficient from the storage tank. While on the other hand, the collector angle and the ambient have a greater effect on the above-mentioned parameters.

This paper is devoted to investigate the behavior of prestressed concrete beams under pure torsion using a non-linear three-dimensional finite element model. The 20-noded isoparametric brick elements have been used to model the concrete. The reinforcing bars are idealized as axial members embedded within the concrete element and perfect bond between the concrete and the reinforcement has been assumed to occur.

The behavior of concrete in compression is simulated by an elasto-plastic work hardening model followed by a perfect plastic response, which is terminated at the onset of crushing. On the other hand the behavior in tension is simulated by implementing a smeared crack model in connection with using a tension-stiffening model that account for the retained post-cracking stresses, and a shear retention model that modifies the shear modulus of rigidity as the crack widens. Also a model to simulate the reduction in the concrete compressive strength in presence of tensile transverse straining has been implemented in this study. Two types of prestressed concrete beams under torsion have been analyzed and the finite element solutions were compared with the experimental data. Several parametric studies have been carried out to investigate the effect some important material parameters. In general, good agreement between the finite element solutions and the experimental results was obtained.

The compressive strength of cement is regarded as a principal indicator to determine the quality of cement. Therefore, efforts were focused to combine the factors which affect compressive strength together in such a form to develop suitable statistical models for predicting strength of cement at various ages (3 and 7 days).

Using SPSS16 software, a statistical analysis is performed for (574) observations taken from archive of quality control at Kerbala Cement Plant, which produces low alkalis sulphate resisting Portland cement. These data sets include compressive strength at 3 and 7 days with various independent variables.

Stepwise regression results in multiple linear models that explain (99.7 %) and (99.9 %) of variations in 3-days and 7-days compressive strength respectively in function of; C3S, C2S, C3A, SO3 contents, and Insoluble residue (IR). The developed models show that these contents positive effect on strength, but (I.R) content has a negative one. Such models could be used in quality control of SRPC factories to enable the manufacturer to make corrections in process within production stage. The sufficient data used in the analysis assures confidence of the developed statistical model.

This study based on laboratory experiments for computing depth of local scour around abutment and bridge pier neighboring abutment considering the study of the effects of upstream flow conditions , pier and abutment sizes , median size of bed material and spacing between pier and abutment on the maximum scour depth and scour pattern around a pier and abutment.

The study was conducted using a physical hydraulic model of pier and abutment operated under subcritical flow , clear-water condition and using uniform cohesionless sand as bed material . Three different size models of pier and abutment were used to show the effect of the size on the local scour and two different median size (d50) of sand were used in this study.

Dimensional analysis techniques and statistical analysis were used to find new formulas with help of the experimental data . One of these formula was to compute the maximum scour depth at pier neighboring abutment and the other to find the maximum scour depth at abutment.

There formula were derived to predict the maximum scour depth in terms of Froude number , diameter of pier and abutment , median size of sand , flow depth , flow velocity and spacing between pier and abutment.

The aim of this research is to investigate the low-velocity impact response of different types of sandwich beams. The test beams were subjected to low- velocity impact loading using drop mass setup, at three energy levels. The data were collected for each specimen, which included time, force, deflection, and energy.

The absorbed energy was evaluated and compared for different types of sandwich beams. Qusi-static tensile and flexural tests were performed to obtain the mechanical properties of the face sheets and the core. The results showed that the specimens with face sheets of fiber at 90º had the maximum peak impact force and deflection, while the specimens with face sheet of random fiber had the minimum peak impact force and deflection. Concerning the absorbed energy, it was maximum in the specimens with random fiber face sheets and minimum in the type with unidirectional fiber 90º face sheets.

This work aims to study the ability of austempering DIN CK50 and DIN 62SiMnCr4 steels. Both steels were heated to austenitising temperature and then quenched in a molten metal bath (pure lead) at temperature below the nose of the TTT curves for both steels. Results showed that austempering at 350oC and 400oC for 30 and 15 minutes are the best for above steels respectively, where strength was increased. It was also shown that increasing holding (soaking) time decreases both hardness and strength and increasing elongation percentage. Microstructure examination showed that the majority of microstructures obtained from austempering vary from bainite and pearlite and ferrite for carbon steel to a mixture of bainite, retained austenite and martensite for the alloy steel.

Reliable prediction of sediment discharge is very important element in the evaluation of sedimentation in reservoir , local scour or deposition around hydraulic structures , river bed degradation , etc.The existing sediment discharge formulas are derived in flumes or tested with limited field data . Hence , the performance of these formulas are unknown in reference with measured flow and data of sediment in natural river. This paper presents the evaluation of eight existing sediment transport formulas (Enguland-Hanssen,Ingls-Lacey, Ackers-White,Yang1972,Yang 1978,Bagnold,Ariffin and Van Rijn) against the field data obtained from twenty cross sections along entire study reach (up- stream AL-Abbasiya Barrage) .Measured data included the hydraulic parameters of different cross sections and the properties of sediment particles.Samples of water sediment have been taken at each section in addition to bed samples using home- made samplers, while hydraulic parameters were founded using Acoustic Doppler Current Profile (ADCP) device.Although significant deviations are found between predictions and measured values in these evaluations , two formulas respectively (Acker-White and Van Rijn)gave a reasonably good agreement .