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RISS 인기검색어
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- 저자 : Ketabdari, (검색결과 4 건)
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Effects of discontinuous submerged breakwater on water surface elevation
Ketabdari, Mohammad J.,lamouki, Mohammad Barzegar Paiin,Moghaddasi, Alireza Techno-Press 2015 Ocean systems engineering Vol.5 No.4
Submerged breakwaters are used to prevent shore line erosion and sediment transportation. One of their advantages is low visual impact. In this paper, the effects of discontinuous submerged breakwaters over water surface elevation was numerically studied considering the extended Boussinesq equations as governing equations using MIKE21 software. The result of discontinuous breakwater was compared with a beach without breakwater. The results showed that the gap dramatically effects on surface elevation from shore line to offshore. It is also evident from results that with approaching the center of the gap, fluctuation of surface elevation is generated. It is because of passing longshore currents towards offshore through the gap which leads to an increase in sediment transportation rate. Nevertheless, transferring water mass from breakwater gap results in powerful rip currents leading to high changes on longshore wave profile.
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M. J. Ketabdari,H. Saghi,H. Rezaei,K. Rezanejad 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.4
In this research, a numerical model is developed for optimization of storage tanks based on sloshing phenomenon. The sloshing of the liquid can increase the dynamic pressure on the partially filled storage tank sidewalls and bottom to endanger its integrity. The coupled boundary element-finite element methods were used to solve the Laplace equation as governing equation and nonlinear free surface boundary conditions. The numerical model is validated against available data. Different sections for the liquid storage tanks such as rectangular tank with different aspect ratios, trapezoidal tanks with linear and nonlinear sidewalls, different sidewall angles and different widths were examined. Finally the best cross sections of storage tank based on minimization of the pressure and forces exerted on the perimeter of the tank due to sloshing phenomenon were suggested. The results showed that using nonlinear sidewalls in storage tank dramatically decreases the sloshing pressure on the perimeter of the tank.
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Seismic Reliability of Concrete Buildings Considering Probabilistic Distribution of Crack
Mohammad Safi,Majid Koolivand,Hesamoddin Ketabdari,Mahsa Rasouli 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.1
One of the effective factors in the analysis of concrete structures is consideration of the effect of cracking on the structural elements, which directly affects the calculation of the natural periods, the story displacement and other response parameters. In different codes for design of concrete structures, cracking effect is considered as a mean and constant coefficient for each element, while clearly the condition of various components will be different based on loading situation and specifications. In this paper, reliability of stiffness reduction coefficients of the beams and columns due to cracking of concrete in the ACI code is investigated under random distribution of floor live loads using Monte Carlo simulation method, By considering 1,000 modelling loops, calculating accurate crack coefficients of beams and columns and applying them in each model, the reliability of cracking coefficients has been obtained. The results show that the reliability index of these coefficients is very low. Also, other results of this modeling and applying accurate cracking coefficients show that the story displacements and the time period of first and second modes decrease about 40 − 55% and 20 − 30%, respectively, and the reaction forces of the elements, especially the axial and torsional forces increase about 20 − 30%.
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Abaiee, M.M.,Ahmadi, A.,Ketabdari, M.J. Korean Society of Ocean Engineers 2015 Journal of advanced research in ocean engineering Vol.1 No.1
Floating structure such as tension leg platform, semi-submersible and spar are widely used in field of oil exploration and renewable energy system. All of these structures have the base cylinder support structure which have effective rule in overall dynamic of response. So the accurate and reliable modeling is needed for optimum design and understanding the physical background of these systems. The aim of this article is an analytical discussion on stochastic modeling of floating cylinder based support structure but an applicable one. Due to this a mathematical mass-damper-spring system of a floating cylinder of HAWAII WTG offshore wind as an applicable and innovative system is adopted to model a coupled degrees using random vibration in analytical way. A fully develop spectrum is adopted to solve the stochastic spectrum analytically by a proper approximation. Some acceptable assumption is adopted. The simplified but analytical and innovative hydrodynamic analysis of this study not only will help researcher to concentrate more physically on hydrodynamic analysis of floating structures but also can be useful for any quick, simplified and closed form analysis of a complicated problem in offshore engineering.
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