Articles in This Issue
Abstract
AbstractConstruction of concrete structures involves at least two different main materials: concrete and steel. Design of these structures should be based on cost rather than weight minimization. In this work, least cost design of singly and doubly reinforced beams is done by applying of the Lagrangian multipliers method (LMM) under ultimate design constraint beside other constraints. Cost objective functions and moment constraints are derived and implemented within the optimization method. The optimum solution comparisons with conventional design methods are performed and the result reported, showing that the LMM can be successfully applied to the minimum cost deign of reinforced concrete beams without need for iterative trials. Optimum design solution surfaces have been developed. Good and reliable results have been obtained and confirmed by using standard design procedures. The artificial neural networks (ANN) has been trained with design data obtained from optimal design formulas. After successful trials, the model predicted the optimum depth of the beam sections and optimum areas of steel required for the problems with accuracy satisfying all design constraints.
Abstract
This research investigates the efficiency of Ultrasonic Pulse Velocity (UPV) method in detecting voids and depth of cracks in concrete. Tests were performed to compare the accuracy between the direct and indirect method of Ultrasonic Pulse Velocity method (UPV) in detecting the location of defects. Three concrete prisms with fabricated void at a known location were used and tested at 28 day. Two other prisms were casted and tested to detect of crack depth in concrete, cracks at depth of 5 and 10 cm perpendicular to axis of beam were induced without actually breaking the beam. Test results indicate that direct and indirect methods can be used to assess the in-situ properties of concrete or for quality control on site, and the first and second method of determining the crack depth gave results with high accuracy while the results of third method were lower than the actual crack depth and for the forth method were higher than it. Therefor, we can use the average of the third and forth results to obtain the crack depth with good accuracy.
Abstract
Considering the corporations of the projects engineering in the universities from important corporations because they which work from projects contribute in prosperity and development of construction. Although for the quality management importance and concept application on the effects of these corporations, therefore must be first application quality management in these projects. The aim of this research to study the management system which used in the engineering affairs corporation (University of Tikrit study case). The harmony evaluation purpose between the management systems with the quality management system dependency on the tests menus which limited I.S.O. 9001/2000 and visit the corporation of projects engineering in university of tikrit for study the management system. Where as a questionnaire form was prepared, included answer on the questions of the tests menus, questionnaire distributed on the group of corporation engineering staff and some engineers whose they worked past in this corporation to fill the answers on questionnaire. The questionnaire results show that this corporation suffer disadvantage very clear in the corporation system structure. After that the Researchers suggest the management system build which can be more active and with high response on requirements of quality managemen
Abstract
AbstractThe aim of this study is to analyze the slope stability for sections in Al-Furat River where engineering construction build on it, when a sudden decrease in the river water level happens. Two sections were chosen from the river in the area located about 35 km away from Ramadi city called Tel Aswad where undisturbed samples are taken and laboratory tests are done to obtain the soil parameters which are used in Geo-Slope program. The finite element method was applied in this study with elastic-plastic soil model. The analysis results show that the sections slope chosen from the river are stable. The second purpose of this analysis to reduce the risk of using earth structures when engineering construction build on it. Also, it is clear that the values of factor of safety calculated by the FEM are low compared with limit equilibrium methods.
Abstract
AbstractA geophysical study using seismic wave velocities data, including compressional and shear wave velocity (Vp and Vs) values, for 14 sites has been carried out. These sites are located within the Mesopotamian plain and surroundings. Both seismic and geotechnical data have been conducted by the National Center for Construction Laboratories and Research (NCCLR) in Iraq. Some geotechnical parameters have been deduced from seismic velocities either from Vp or Vs. Correlations between seismic velocities (Vp and Vs) and geotechnical properties have been derived. These relations show direct proportionalities between Vp and Vs with standard penetration test (SPT-N value). LiuefyPro software has been utilized for two selected Iraqi sites to investigate the liquefaction potential. Input data of the program will be based on those derived from the compressional and shear wave velocities. The application shows a total settlement for saturated and dry sand of 32 mm for the first site while no settlement has been indicated for the second site. It was found that the high value of both wave velocities for a cohesionless fully saturated soil gives an indication that this soil is unable to liquefy and settle under earthquake excitation and vice versa.
Abstract
This research includes study of the of effect of adding sulphur, which is obtained from Samrraa factory on the properties of concrete like compressive strength, flexural strength and splitting tensile strength. The concrete mixes were: (1:8.5:8.5:7), (1:8.5:8.5:9), (1:8.5:8.5:12) and (1:1.5:3:0) (cement: sand: gravel: sulphur) respectively. The results refer to increasing of compressive strength , flexural strength and splitting tensile strength with increasing of sulphur ratio but increasing decreased at age (28)day with respect to ordinary concrete (sulphur ratio=0%).
Abstract
This research includes study the effect of fineness upon physical properties of cement mortar where use ordinary Portland cement with fineness (300 m2/kg) as reference mixture which denoted by symbol (M1), and then produce with flowing fineness (350,400,450 and 500 m2/kg) which denoted by ( M2, M3, M4, M5 ) respectively . The results of study show that increasing in fineness makes an increase in water quantity that requires for consistence of standard paste and the ratio of above mixes with reference mixture (2%,5%,7%,11%)respectively, although the increasing in density for all ages and increasing in compressive strength in early age, the increasing ratio in 3 days age was ( 45% , 50% , 60% , 70%)respectively .this increasing in fineness makes increasing in ratio of flow as compared with reference mix(16%, 25%, 50%, 66%) respectively
Abstract
AbstractThis research includes the study of the effect of adding steel fibres resulting from cutting chicken wire (which is available in Iraqi markets now) as fibres added to the polymer concrete. These fibres were added with percentages of concrete volumes. These percentages were (0.5%) and (1%). Reference concrete mix was also made for comparative reasons. From the results, it can be noted that the increasing of compressive strength of SFPC1 comparing with RPC at 28 days equal to 9.90%, whereas the increasing of compressive strength of SFPC2 comparing with RPC at 28 days is equal to 15.48%. The increasing of splitting strength of SFPC1 comparing with RPC at 28 days equal to 15.50%, whereas the increasing of SFPC2 comparing with RPC at 28 days is equal to 21.40%. The increasing of flexural strength of SFPC1 comparing with RPC at 28 days equal to 10.80%, whereas the increasing of SFPC2 comparing with RPC at 28 days is equal to 20.63%.Results proved that adding of steel fibres with these percentages lead to improvements in compressive strength, splitting strength and flexural strength of concretes containing steel fibres, but the improvement in flexural strength appeared more clearly. Results proved also an increasing in densities of fibre concrete samples according to these made of reference mix.
Abstract
AbstractSemi-empirical equation for water flow through packed bed of sphere particles of mono size packing system has been estimated depending on Buckingham theorem. Different parameters affecting the pressure drop of fluid flow through packed bed have been studied. These parameters are fluid velocity, bed porosity, bed diameter, sphericity, particle diameter, packing height and wall effect. Several types and kinds of packing materials have been used in this study such as (Pea Gravel, Marbles, Glass Marbles, Black Marbles, Clear Marbles, Acrylic balls and Glass spheres). The diameters of the packing materials used in this model are from the range of (0.2-8.89) cm, the porosity is from the range of (0.3-0.47), the bed diameters is from the range of (7.62 - 15.24) cm and the height of packing is from the range of (26.03 - 55.88) cm. πThe results of all calculations for the estimated equations have been compared with many documented experimental literatures. This comparison gave a very good agreement, and has been represented in curves. The results from Ergun equation using similar conditions have been represented in the curves for the sake of comparison.
Abstract
AbstractThis work presents the study of water flow through a packed bed containing spherical glass particles distributed randomly. The packed bed was 7.62 cm in diameter and 57 cm long. The glass particles were 0.42, 0.50, 0.61, 0.79 and 1.01 cm in diameter. Different flow rates of fluid were used which expressed by modified Reynolds number. The experiments were carried out at laboratory temperatures at city water temperature (25◦C) for water flow. Many variables were studied in this work such as fluid type, flow rate and the packing porosity, in order to study the effect of these variables on the pressure drop and friction factor. The results showed that the pressure drop through a packed bed is highly sensitive to the packing porosity which has a significant effect on the friction factor. It was found that as the bed porosity increases the friction factor values as well as the pressure drop values decrease.Empirical correlation for friction factor as a function of Reynolds number for water flow through packed of mono size packing has been made, and can be written as follows: The correlation coefficient was 0.97406 and percentage of average errors was 2.44%.
Abstract
AbstractThe crystalline zeolite, namely faujasite type Y with SiO2/Al2O3 mole ratio of 5 was used as raw material for preparation of isomerization catalysts. Decationized HY-zeolite was prepared by treating Na Y-zeolite with solution of 4N ammonium chloride through ion exchange, drying at 110°C, and calcination initially at 150°C and the temperature increased to 525°C with a rate of 75°C/h to liberate NH3 and water. Then, HY-zeolite was reduced with hydrogen at 380°C, then fabricated as a spherical shape and calcined at 400°C.A 0.5 wt % Pt/HY-zeolite catalyst was prepared by impregnation with chloroplatinic acid. The catalyst was dried at 110°C over night, calcined at 400°C and reduced with hydrogen at 380°C. The prepared catalyst powder was then formulated as a spherical shape with 20% sodium silicate. The decationized HY-zeolite was treated with HCl, HNO3 and HI promoters using different normalities and with different concentrations of Sn, Ni and Ti promoters by impregnation method to obtain acidic and metallic promoters' catalysts, respectively. A 0.5 wt% of Pt was added to above catalysts using impregnation method. The catalysts were then dried, calcined, reduced and formulated using the same steps in preparation of Pt/HY-zeolite catalyst.