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CONTENTS
Volume 6, Number 4, December 2017
 

Abstract
The present paper deals with the influence of the inclination of cables\' system on the decrease of the lateral-torsional motion because of dynamic loadings. For this goal, a mathematical model is proposed. A 3-D analysis is performed for the solution of the bridge model. The theoretical formulation is based on a continuum approach, which has been widely used in the literature to analyze such bridges. The resulting uncoupled equations of motion are solved using the Laplace Transformation, while the case of the coupled motion is solved through the use of the potential energy. Finally, characteristic examples are presented and useful results are obtained.

Key Words
suspension bridges; footbridges; dynamic behavior; damping systems

Address
Ioannis Raftoyiannis and George Michaltsos: National Technical University of Athens, Department of Civil Engineering, 15780, Greece
Theodore Konstantakopoulos: University of Thessaly, Greece

Abstract
This paper deals with the nonlinear static deflections of functionally graded (FG) porous under thermal effect. Material properties vary in both position-dependent and temperature-dependent. The considered nonlinear problem is solved by using Total Lagrangian finite element method within two-dimensional (2-D) continuum model in the Newton-Raphson iteration method. In numerical examples, the effects of material distribution, porosity parameters, temperature rising on the nonlinear large deflections of FG beams are presented and discussed with porosity effects. Also, the effects of the different porosity models on the FG beams are investigated in temperature rising.

Key Words
functionally graded material; porosity; nonlinear analysis; total langragian finite element model; large deflections

Address
Şeref D. Akbaş: Department of Civil Engineering, Bursa Technical University, Yildirim Campus, Yildirim, Bursa 16330, Turkey


Abstract
This paper shows a comparative study for design of reinforced concrete boundary combined footings of trapezoidal and rectangular forms supporting two columns and each column transmits an axial load and a moment around of the axis X (transverse axis of the footing) and other moment around of the axis Y (longitudinal axis of the footing) to foundation to obtain the most economical combined footing. The real soil pressure acting on the contact surface of the footings is assumed as a linear variation. Methodology used to obtain the dimensions of the footings for the two models consider that the axis X of the footing is located in the same position of the resultant, i.e., the dimensions is obtained from the position of the resultant. The main part of this research is to present the differences between the two models. Results show that the trapezoidal combined footing is more economical compared to the rectangular combined footing. Therefore, the new model for the design of trapezoidal combined footings should be used, and complies with real conditions.

Key Words
design of trapezoidal combined footings; design of rectangular combined footings; bending moments; bending shear; punching shear

Address
Arnulfo Luevanos-Rojas, Sandra Lopez-Chavarria and Manuel Medina-Elizondo: Institute of Multidisciplinary Researches, Autonomous University of Coahuila,
Blvd. Revolucion No, 151 Ote, CP 27000, Torreon, Coahuila, Mexico
Jose Daniel Barquero-Cabrero: Institute for Long Life Learning IL3, University of Barcelona,
Street Girona No, 24, CP 08010, Barcelona, Spain

Abstract
The hydro-elastic system consisting of a pre-stretched highly elastic plate, compressible Newtonian viscous fluid, and the rigid wall is considered and it is assumed that on the plate a lineal-located time-harmonic force acts. It is required to investigate the dynamic behavior of this system and determine how the problem parameters and especially the pre-straining of the plate acts on this behavior. The elasticity relations of the plate are described through the harmonic potential and linearized (with respect to perturbations caused by external time-harmonic force) form of these relations is used in the present investigation. The plane-strain state in the plate is considered and the motion of that is described within the scope of the three-dimensional linearized equations of elastic waves in elastic bodies with initial stresses. The motion of the fluid is described by the linearized Navier-Stokes equations and it is considered the plane-parallel flow of this fluid. The Fourier transform with respect to the space coordinate is applied for a solution to the corresponding boundary-value problem. Numerical results on the frequency response of the interface normal stress and normal velocity and the influence of the initial stretching of the plate on this response are presented and discussed. In particular, it is established that the initial stretching of the plate can decrease significantly the absolute values of the aforementioned quantities.

Key Words
compressible viscous fluid; highly elastic plate; initial strain; frequency response; forced vibration; rigid wall

Address
Surkay D. Akbarov:
1) Yildiz Technical University, Faculty of Mechanical Engineering, Department of Mechanical Engineering, Yildiz Campus, 34349, Besiktas, Istanbul, Turkey
2) Institute Mathematics and Mechanics of the National Academy of Sciences of Azerbaijan, AZ141, Baku, Azerbaijan
Meftun I. Ismailov: Nachicivan State University, Faculty of Mathematics, Nachicivan, Azerbaijan
Soltan A. Aliyev: Yildiz Technical University, Faculty of Mechanical Engineering, Department of Mechanical Engineering, Yildiz Campus, 34349, Besiktas, Istanbul, Turkey

Abstract
In this paper, free vibration and static response of magneto-electro-elastic (MEE) beams has been investigated. To this end, a 3D finite element formulation has been derived by minimization the total potential energy and linear constitutive equation. The coupling between elastic, electric and magnetic fields can have a significant influence on the stiffness and in turn on the static behaviour of MEE beam. Further, different Barium Titanate (BaTiO3) and Cobalt Ferric oxide (CoFe2O4) volume fractions results in indifferent coupled response. Therefore, through the numerical examples the influence of volume fractions and boundary conditions on the natural frequencies of MEE beam is illustrated. The study is extended to evaluate the static response of MEE beam under various forms of mechanical loading. It is seen from the numerical evaluation that the volume fractions, loading and boundary conditions have a significant effect on the structural behaviour of MEE structures. The observations made here may serve as benchmark solutions in the optimum design of MEE structures.

Key Words
magneto-electro-elastic; volume fractions; piezoelectric and piezomagnetic, free vibration

Address
Vinyas. M and S. C. Kattimani: Department of Mechanical Engineering, National Institute of Technology Karnataka,
Surathkal-575025, India


Abstract
This paper investigates the approximate solution bounds of radon diffusion equation in soil pore matrix coupled with uncertainty. These problems have been modeled by few researchers by considering the parameters as crisp, which may not give the correct essence of the uncertainty. Here, the interval uncertainties are handled by parametric form and solution of the relevant uncertain diffusion equation is found by using Galerkin\'s Method. The shape functions are taken as the linear combination of orthogonal polynomials which are generated based on the parametric form of the interval uncertainty. Uncertain bounds are computed and results are compared in special cases viz. with the crisp solution.

Key Words
radon; orthogonal; coupled; polynomials; crisp; uncertainty; interval

Address
T.D. Rao and S. Chakraverty: Department of Mathematics, National Institute of Technology Rourkela, Odisha, 769008, India

Abstract
This paper introduces a numerical procedure to incorporate elasto-plastic local deformation effects in the dynamic analysis of beams. The appealing feature is that simple beam type finite elements can be used for the global model which needs not to be altered by the localized elasto-plastic deformations. An overlapping local sophisticated 2D membrane model replaces the internal forces of the beam elements in the predefined region where the localized deformations take place. An iterative coupling technique is used to perform this replacement. Comparisons with full membrane analysis are provided in order to illustrate the accuracy and efficiency of the method developed herein. In this study, the membrane formulation is able to capture the elasto-plastic material behaviour based on the von Misses yield criterion and the associated flow rule for plane stress. The Newmark time integration method is adopted for the step-by-step dynamic analysis.

Key Words
iterative global-local method; multi-scale analysis; finite elements; elasto-plastic behavior; structural dynamics

Address
R. Emre Erkmen and Ashkan Afnani: School of Civil and Environmental Engineering, University of Technology, Sydney, 15 Broadway, Ultimo NSW 2007, Australia


Abstract
This study aims to investigate the capacity of different models to reproduce the nonlinear behavior of reinforced concrete framed structures. To accomplish this goal, a combined experimental and analytical research program was carried out on a large scaled reinforced concrete frame. Analyses were performed by SAP2000 and compared to experimental and VecTor2 results. Models made in SAP2000 differ in the simulation of the plasticity and the type of the frame elements used to discretize the frame structure. The results obtained allow a better understanding of the characteristics of all numerical models, helping the users to choose the best approach to perform nonlinear analysis.

Key Words
nonlinear analysis; pushover analysis; frame structure; experimental testing; numerical model; SAP2000; hinges properties

Address
Amir Salihovic and Naida Ademovic: Faculty of Civil Engineering at University of Sarajevo, Patriotske lige 30, 71000 Sarajevo, Bosnia and Herzegovina



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