JOURNAL OF FACULTY OF ENGINEERING (UNIVERSITY OF TABRIZ)
Year:2005 | Volume:31 | Issue:2 (39) CIVIL ENGINEERING|Papers Count:8

In this paper application of GPS observation for determination of water vapor of the Earth’s atmosphere has been studied based on 4 permanent GPS stations, namely, PERM (in Iran), BAHR (in Bahrain), KIT3 (in Kazakhstan), and NSSP (in Armenia). The obtainable accuracy of the water vapor by GPS has been investigated by comparison of the computed Zenith Total Delay (ZTD) in this study at the KIT3 station by that computed by International GPS Service (IGS). The results of the comparison ensuring the success of atmospheric water vapor determination by GPS and as such the presented methodology can be readily applied at all existing permanent GPS station of the country and those that would be established in future. Since so far there has been no permanent station for the observation of the water vapor in Iran, the results of this study provides the possibility of using the permanent GPS stations, in addition to their geodynamic and positioning missions for the meteorological applications.

In this paper details of the numerical model results of the layer integrated model for the square river harbour, using the zero-and two-equation turbulence models are discussed. For the zero-and two-equation turbulence models, the modified mixing length and depth integrated k-e models were deployed to calculate the horizontal eddy viscosity coefficients, respectively. Likewise, the parabolic distribution and layer integrated k-e models were used to determine the vertical eddy viscosity. The model was applied for prediction of flow within the river and harbour and the various numerical model and experimental results were then compared graphically with each other. General study of the numerical model results showed that the zero-equation model has predicted small values for the velocity components within the harbour, whereas the two-equation model has predicted reasonable values for the flow components and these values were relatively in good agreement with the experimental results. Also, the numerical model results of the vertical profile of horizontal velocity components have shown the capability of the k-e turbulence model in predicting the experimental data.

This paper investigate influence of various parameters on the nonlinear behavior of R.C. deep beams. Reinforced Concrete deep beams are one of the structural element that used in dams, offshore piers, rectangular tanks, bridges, floors, diaphragms and high rise buildings. Definition of deep beam by various codes is based on span to height of beam ratio. Generally, span to height ratio of deep beams required not to be greater 2.5. In this paper, three deep beams which have been tested in laboratory already, have been analyzed with various number of element by a nonlinear layered finite element program. In the nonlinear analysis section, results include vertical load versus vertical displacement curve, crack pattern, cracking load and ultimate load. For investigating deep beams behavior, a parametric study used to investigate size–effect phenomenon, tension and compression strength of concrete, yield strength of reinforcement (bar), amount of longitudinal and vertical reinforcement, location and percentage of opening. Also, a new method proposed for placing reinforcement cage in the shear failure area and analytical results compared to experimental results. Results comparison show that nonlinear layered finite element method can be used for investigating of R.C. deep beams with high accuracy.

In this paper the stability analysis of X-Bracing systems is performed and a simple and effective mid-span connection detailing is proposed. This detailing can improve the load carrying capacity of the X-Bracing as well as behavior of the bracing system. In the common detailing for mid-span, one diagonal (which is comprised of a pair of channel or angle section) is cut at the mid-span connection, so the other diagonal is continuously passed from the cross connection. In the proposed method one section from each diagonal is cut and the other section is continuous so each diagonal is semi-continuous at the cross connection. There are three kinds of mid-connection which may be verified: a-continuous b-discontinuous (hinged) c-semi-continuous. In this research the stability of the above three cases are studied and several experiments are done. Then the theoretical methods are improved. These results show that the detailing of mid-connection can affect on the load carrying capacity of X-bracing and it must be taken into account in the design.

In this paper a nonlinear analysis of the earthquake hydrodynamic pressure on dam bodies using the Navier Stokes equations is used. The finite volume method SIMPLEC scheme for discretization of the Navier Stokes and continuity equations are utilized. Boundary conditions on the dam body and reservoir bed were applied. The nonlinear discretized equations were solved using Thomas algorithm by an iterative scheme. The hydrodynamic force exerted on the dam body was obtained by the integration of the calculated pressures. This Force is a function of time and hence it can be determined at any time interval. A computer program using the visual basic language was developed for the analysis to determine velocity components, pressures at nodal points of the reservoir grid including the face of the dam body, and reservoir water surface profile as a function of time due to an earthquake considering surface waves and nonlinear convective terms. Results were compared to those obtained by other researchers. The comparison indicates that the accuracy and convergence are quite satisfactory. The results were also compared with an analytical solution to investigate influences of surface waves and nonlinear convective terms.

Dispersive soils dilute as colloids when they are exposed to water. The most important characteristic of these soils is presence of a large amount of Na ion in their pore water. Electro-osmosis is one on of the electro-kinetic phenomena in which the liquid moves relative to the solid phase under the influence of an externally applied electrical potential. This causes the positive ions move from anode towards cathode; following which the moisture content and TDS value of the soil near by the anode are decreased and it is highly treated to become non-dispersive. At cathode, however, the dispersivity become even worse. These phenomena initiates several physical and chemical changes in soil which are appreciated in the current paper. This paper presents results of a laboratory research program in which the pH value of the inflow fluid, and in some cases also outflow fluid, at anode and cathode, are changed and their effects on the efficiency of the electro-osmotic treatment of test specimens are evaluated. It was observed that the soil is best treated when the inflow and outflow fluids are acidic and base respectively. As the treatment proceeds the current density decreases due to the increase of soil electrical resistance When the ultimate treatment has been achieved the pH value of the soil at anode and at cathode decreases and increases, respectively. In the same time the plastic and liquid limits increase both at anode and at cathode. However, this effect is more eminent at anode.

The purpose of an altimeter is to make accurate and precise measurements of surface height. Height refers to the distance of the surface above a reference and is computed from satellite altitude and altimeter range. In order to fully assess the accuracy of the altimeter measurements, accurate ground height data in a digital formal and with a sufficient coverage are required to compare with the altimeter height data. Ideally height values are needed to be better than the expected precision of the altimeter. The only satisfactory way to compare Radar Altimeter (AR) data with accurate co- ordinate data is comparing the calculated RA height data with the available accurate data on a point by point basis. To compare the height data all data should be on the same datum which means the same ellipsoid. However, the map will be referenced to local sea level rather to an ellipsoid and geoid. In the case when different datum levels are used this makes a comparison difficult and it is best to look at the height difference changes.