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CONTENTS
Volume 27, Number 4, October 2018
 

Abstract
In the desert and Gobi regions with strong wind and large sediment discharge, sand transporting engineering is more effective than sand blocking and sand fixing measures in sand prevention. This study uses the discrete phase model of 3D numerical simulation to study the motion trail, motion state and distribution rule of sand particles with different grain diameters when the included angle between the main shaft of the feather-row lateral transportation sand barrier and the wind direction changes, and conducts a comparison in combination with the wind tunnel test and the flow field rule of common sand barrier. According to the comparison, when wind-sand incoming flow passes through a feather-row sand barrier, sand particles slow down and deposit within the deceleration area under the resistance of the feather-row sand barrier, move along the transportation area formed by the transportation force, and accumulate as a ridge at the tail of the engineering. With increasing wind speed, the eolian erosion of the sand particles to the ground and the feather-row sand barrier is enhanced, and the sand transporting quantity and throw-over quantity of the feather-row sand barrier are both increased. When sand particles with different grain diameters bypass the feather-row sand barrier, the particle size of the infiltrating sands will increase with the included angle between the main shaft of the feather-row sand barrier and the wind direction. The obtained result demonstrates that, at a constant wind speed, the flow field formed is most suitable for the lateral transportation of the wind-drift flow when the included angle between the main shaft of the feather-row sand barrier lateral transportation engineering and the wind speed is less than or equal to 30

Key Words
3D numerical simulation; discrete phase model; wind-sand two-phase flow; lateral transportation; rule of motion

Address
Lin-gui Xin, Jian-jun Cheng, Bo-yu Chen and Rui Wang: College of Water Resources and Architectural Engineering, Shihezi University, Shihezi Xinjiang 832003, China

Abstract
In this study, a simplified three-dimensional calculation model is developed for the dynamic analysis of soil-pile group-supertall building systems excited by wind loads using the substructure method. Wind loads acting on a 300-m building in different wind directions and terrain conditions are obtained from synchronous pressure measurements conducted in a wind tunnel. The effects of soil-structure interaction (SSI) on the first natural frequency, wind-induced static displacement, root mean square (RMS) of displacement, and RMS of acceleration at the top of supertall buildings are analyzed. The findings demonstrate that with decreasing soil shear wave velocity, the first natural frequency decreases and the static displacement, RMS of displacement and RMS of acceleration increase. In addition, as soil material damping decreases, the RMS of displacement and the RMS of acceleration increase.

Key Words
soil-structure interaction; dynamic responses; wind load; supertall building; pile group

Address
Yajun Huang and Ming Gu: State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, 1239 Siping Road, Shanghai, China


Abstract
In this study the stress analysis of orthotropic thin plate with arbitrary shapes for different boundary conditions is investigated. Meshfree method is applied to static analysis of thin plates with various geometries based on the Kirchhoff‎ classical plate theory. According to the meshfree method the domain of the plates are expressed through a set of nodes without using mesh. In this method, a set of nodes are defined in a standard rectangular domain, then via a third order map, these nodes are transferred to the main domain of the original geometry; therefore the analysis of the plates can be done. Herein, Meshless local Petrov–Galerkin (MLPG) as a meshfree numerical method is utilized. The MLS function in MLPG does not satisfy essential boundary conditions using Delta Kronecker. In the MLPG method, direct interpolation of the boundary conditions can be applied due to constructing node by node of the system equations. The detailed parametric study is conducted, focusing on the arbitrary geometries of the thin plates. Results show that the meshfree method provides better accuracy rather than finite element method. Also, it is found that trend of the figures have good agreement with relevant published papers.

Key Words
Meshfree; Mindlin classical plate

Address
H. Edalati:Faculty of Mechanical Engineering‎, Jasb Branch, Islamic Azad University, Jasb, Iran
B. Soltani: Faculty of Mechanical Engineering, University of Kashan, Kashan

Abstract
In this paper, a simple first-order shear deformation theory is presented for dynamic behavior of functionally graded beams. Unlike the existing first-order shear deformation theory, the present one contains only three unknowns and has strong similarities with the classical beam theory in many aspects such as equations of motion, boundary conditions, and stress resultant expressions. Equations of motion and boundary conditions are derived from Hamilton\' s s principle. Analytical solutions of simply supported FG beam are obtained and the results are compared with Euler-Bernoulli beam and the other shear deformation beam theory results. Comparison studies show that this new first-order shear deformation theory can achieve the same accuracy of the existing first-order shear deformation theory.

Key Words
free vibration; functionally graded materials; boundary conditions; shear deformation theories; Hamilton\'s principle

Address
Latifa Ould Larbi: Department of Civil Engineering, Faculty of Civil Engineering and Architecture, University Hassiba Benbouali, Chlef, BP 151, Hay Essalam, UHB Chlef, Chlef (02000), Algeria;
Laboratoire des Matériaux & Hydrologie, Université de Sidi Bel Abbes, 22000 Sidi Bel Abbes, Algeria
Lazreg Hadji:Department of Civil Engineering, Faculty of Civil Engineering and Architecture, University Hassiba Benbouali, Chlef, BP 151, Hay Essalam, UHB Chlef, Chlef (02000), Algeria
Mohamed Ait Amar Meziane:Department of Civil Engineering, Faculty of Applied Sciences, Ibn Khaldoun University, BP 78 Zaaroura, Tiaret (14000), Algeria
E.A. Adda Bedia: Department of Civil Engineering, Faculty of Applied Sciences, Ibn Khaldoun University, BP 78 Zaaroura, Tiaret (14000), Algeria;
Laboratory of Geomatics and Sustainable Development, Ibn Khaldoun University of Tiaret, Algeria




Abstract
This paper investigated the wind-snow flow around the bogie region of a high-speed train under crosswinds using a coupled numerical method of the unsteady Realizable k-e turbulence model and discrete phase model (DPM). The flow features around the bogie region were discussed and the influence of bogie fairing height on the snow accumulation on the bogie was also analyzed. Here the high-speed train was running at a speed of 200 km/h in a natural environment with the crosswind speed of 15 m/s. The mesh resolution and methodology for CFD analysis were validated against wind tunnel experiments. The results show that large negative pressure occurs locally on the bottom of wheels, electric motors, gear covers, while the positive pressure occurs locally on those windward surfaces. The airflow travels through the complex bogie and flows towards the rear bogie plate, causing a backflow in the upper space of the bogie region. The snow particles mainly accumulate on the wheels, electric motors, windward sides of gear covers, side fairings and back plate of the bogie. Longer side fairings increase the snow accumulation on the bogie, especially on the back plate, side fairings and brake clamps. However, the fairing height shows little impact on snow accumulation on the upper region of the bogie. Compared to short side fairings, a full length side fairing model contributes to more than two times of snow accumulation on the brake clamps, and more than 20% on the whole bogie.

Key Words
DPM; side fairing; snow accumulation; high-speed train; bogie

Address
Guangjun Gao, Yani Zhang, Jie Zhang, Fei Xie, Yan Zhang and Jiabin Wang: Key Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha 410075, China;
Joint International Research Laboratory of Key Technology for Rail Traffic Safety, Central South University, Changsha 410075, China;
National & Local Joint Engineering Research Center of Safety Technology for Rail Vehicle, Changsha 410075, China


Abstract
In this paper, a new displacement field based on quasi-3D hybrid-type higher order shear deformation theory is developed to analyze the static and dynamic response of exponential (E), power-law (P) and sigmoïd (S) functionally graded beams. Novelty of this theory is that involve just three unknowns with including stretching effect, as opposed to four or even greater numbers in other shear and normal deformation theories. It also accounts for a parabolic distribution of the transverse shear stresses across the thickness, and satisfies the zero traction boundary conditions at beams surfaces without introducing a shear correction factor. The beam governing equations and boundary conditions are determined by employing the Hamilton\'s principle. Navier-type analytical solutions of bending and free vibration analysis are provided for simply supported beams subjected to uniform distribution loads. The effect of the sigmoid, exponent and power-law volume fraction, the thickness stretching and the material length scale parameter on the deflection, stresses and natural frequencies are discussed in tabular and graphical forms. The obtained results are compared with previously published results to verify the performance of this theory. It was clearly shown that this theory is not only accurate and efficient but almost comparable to other higher order shear deformation theories that contain more number of unknowns.

Key Words
functionally graded beam; free vibration; bending; stress; shear deformation theory; stretching effect

Address
Mustapha Meradjah: Laboratoire des Structures et Matériaux Avancés dans le Génie Civil et Travaux Publics, Département de génie Civil, Université de Sidi Bel Abbes, Faculté de Technologie, Algeria
Khaled Bouakkaz: Département de Génie Civil, Université Ibn Khaldoun, BP 78 Zaaroura, 14000 Tiaret, Algeria
Fatima Zohra Zaoui: Laboratory of numerical and experimental modeling of the mechanical phenomena, Department of Mechanical Engineering,
Faculty of sciences and Technology, Ibn Badis University, Mostaganem 27000, Algeria
Abdelouahed Tounsi: Laboratoire des Structures et Matériaux Avancés dans le Génie Civil et Travaux Publics, Département de génie Civil, Université de Sidi Bel Abbes, Faculté de Technologie, Algeria;
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia;
Material and Hydrology Laboratory, Department of Civil Engineering, University of Sidi Bel Abbes, Faculty of Technology, Algeria


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