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CONTENTS
Volume 61, Number 4, February25 2017
 

Abstract
This study investigates the bending of an isotropic thin rectangular plate in finite deformation. Employing hyperelastic material of John\'s type, a non-classical model which generalizes the famous Kirchhoff\'s plate equation is obtained. Exact solution for deflection of the plate under sinusoidal loads is obtained. Finally, it is shown that the non-classical plate under consideration can be used as a replacement for Kirchhoff\'s plate on an elastic foundation.

Key Words
bending; non-classical; thin plate

Address
Odunayo O. Fadodun and Adegbola P. Akinola : Department of Mathematics, Obafemi Awolowo University, Ile-Ife, 220005, Nigeria

Abstract
The need of progress in engineering designs especially for aerospace structure is nowadays becoming a major industry request. The objectives of this work are to quantify the influence of material and operational uncertainties on the performance of the aerodynamic behavior of an Aircraft Wing, and to give a description of the most commonly used methods for reliability based design optimization (RBDO) to point out the advantages of the application of this method in the design process. A new method is proposed, called Safest Point (SP) that can efficiently give the reliability-based optimum solution for freely vibrating structures with and without fluid flow.

Key Words
fluid-structure interaction; aircraft wing; aerodynamic; reliability; RBDO; uncertainties

Address
Rabii El Maani, Abderahman Makhloufi and Abdelkhalak El Hami : LOFIMS, INSA de Rouen, Avenue de l\'Universite, 76800 Saint Etienne de Rouvray, France
Rabii El Maani and Bouchaib Radi : LIMII, FST Settat, route de Casablanca, Settat, Morocco

Abstract
This paper presents the series multiple tuned mass dampers (STMDs) to suppress the resonant vibrations of railway bridges under the passage of high-speed trains (HSTs). A STMD device consisting of two spring-mass-damper units connected each other in series is installed on the bridge. In solution, bridge is modeled as a simply-supported Euler-Bernoulli beam with constant cross-section, and vehicle is simulated as a series of moving forces with constant speed. By the assumed mode method, the governing equations of motion of the beam-TMD device coupled system traversed by a moving train are obtained. The optimum values for the parameters of the STMD device are obtained for the criterion based on the minimization of the maximum dynamic displacement of the beam at its midspan. Single TMD and multiple TMDs in parallel are also considered for demonstration of the STMD device\'s performance. The results show that STMDs are effective in bridge vibration suppression and robust to parameters\' change in the main system and the absorber itself.

Key Words
tuned mass dampers; railway bridges; vibration control; high-speed train; resonant vibrations

Address
Volkan Kahya : Department of Civil Engineering, Karadeniz Technical University, Faculty of Engineering, Trabzon 61080, Turkey
Onur Araz : Department of Civil Engineering, Gümüşhane University, Faculty of Engineering and Natural Sciences, Gümüşhane 29100, Turkey

Abstract
Reinforced concrete is a complex material to be modeled in finite element domain. A proper material model is necessary to represent the nonlinear behaviour accurately. Though the nonlinear analysis of RC structures evolved long back, still an accurate and reliable model to predict the realistic behaviour of components are limited. It is observed from literature that there are three well-known models to represent the nonlinear behaviour of concrete. These models include Chu model (1985), Hsu model (1994) and Saenz model (1964).A new stress-strain model based on Weibull distribution has been proposed in the present study. The objective of the present study is to analyze a reinforced concrete beam under flexural loading by employing all the models. Nonlinear behaviour of concrete is considered in terms of stress vs. strain, damage parameter, tension stiffening behaviour etc. The ductility of the RC beams is computed by using deflection based and energy based concepts. Both deflection ductility and energy based ductility is compared and energy based concept is found to be in good correlation with the experiments conducted. The behavior of RC beam predicted using ABAQUS has been compared with the corresponding experimental observations. Comparison between numerical and experimental results confirms that these four constitutive models are reliable in predicting the behaviour of RC structures and any of the models can be employed for analysis.

Key Words
RC beam; Weibull distribution; ABAQUS; finite element analysis; ductility

Address
A. Ramachandra Murthy : CSIR-Structural Engineering Research Centre, Taramani, Chennai, 600113, India
D. Shanmuga Priya : Dhanalakshmi College of Engineering, Chennai, Tamilnadu, 601301, India

Abstract
An overhead travelling crane structure of two doubly symmetric welded box beams is designed for minimum cost. The rails are placed over the inner webs of box beams. The following design constraints are considered: local buckling of web and flange plates, fatigue of the butt K weld under rail and fatigue of fillet welds joining the transverse diaphragms to the box beams, fatigue of CFRP (carbon fibre reinforced plastic) laminate, deflection constraint. For the formulation of constraints the relatively new standard for cranes EN 13001-3-1 (2010) is used. To fulfill the deflection constraint CFRP strengthening should be used. The application of CFRP materials in strengthening of steel and concrete structures are widely used in civil engineering applications due to their unique advantages. In our study, we wanted to show how the mechanical properties of traditional materials can be improved by the application of composite materials and how advanced materials and new production technologies can be applied. In the optimization the following cost parts are considered: material, assembly and welding of the steel structure, material and fabrication cost of CFRP strengthening. The optimization is performed by systematic search using a MathCAD program.

Key Words
FRP strengthening; crane; welded box beam; fatigue; cost calculation; optimization

Address
Gyorgy Kovacs and Jozsef Farkas : Institute of Logistics, University of Miskolc, Miskolc-Egyetemvaros, Hungary

Abstract
Earthquake excitations may induce important amount of seismic energy into structures. Current design philosophy mainly deals with the plastic deformations of replaceable energy dissipating devices rather than damages accumulated on structural members. Since earthquake damage is substantially concentrated on these devices they could be replaced after severe earthquakes. In this study, the efficiency of steel cushion (SC) on seismic improvement of a vulnerable reinforced concrete (RC) frame is determined by means of several numerical simulations. The cyclic shear behaviors of SCs were determined by performing quasi-static tests. The test results were the main basis of the theoretical model of SCs which were used in the numerical analysis. These analyses were performed on three types of RC frames namely bare frame (BF), full-braced frame (FBF) and semi-braced frame (S-BF). According to analysis results; implementation of SCs has considerable effects in reducing the storey shear forces and storey drifts. Moreover plastic energy demands of structural elements were reduced which indicates a significant improvement in seismic behavior of the RC frame preventing damage accumulation on structural elements. Fullbraced frame having SCs with the thickness of 25 mm has better performance than semi-braced frame interms of energy dissipation. However, global energy dissipation demand of S-BF and F-BF having SCs with the thickness of 18 mm are almost similar.

Key Words
metallic dampers; shear force; storey drift; energy dissipation; nonlinear time history analysis

Address
Hasan ozkaynak : Department of Civil Engineering, Beykent University, Ayazaga 34396 Maslak, İstanbul, Turkey

Abstract
A framed structure may be composed of two sub-structures, which are linked by a hinged joint. One sub-structure is the primary system and the other is the secondary system. The primary system, which is subjected to the periodic external load, can give rise to an auto-parametric resonance of the second system. Considering the geometric-stiffness effect produced by the axially internal force, the element equation of motion is derived by the extended Hamilton\'s principle. The element equations are then assembled into the global non-homogeneous Mathieu-Hill equations. The Newmark\'s method is introduced to solve the time-history responses of the non-homogeneous Mathieu-Hill equations. The energy-growth exponent/coefficient (EGE/EGC) and a finite-time Lyapunov exponent (FLE) are proposed for determining the auto-parametric instability boundaries of the structural system. The auto-parametric instabilities are numerically analyzed for the two frames. The influence of relative stiffness between the primary and secondary systems on the auto-parametric instability boundaries is investigated. A phenomenon of the \"auto-parametric internal resonance\" (the auto-parametric resonance of the second system induced by a normal resonance of the primary system) is predicted through the two numerical examples. The risk of auto-parametric internal resonance is emphasized. An auto-parametric resonance experiment of a

Key Words
auto-parametric resonance; framed structures; finite element modeling; non-homogeneous Mathieu-Hill equation; energy-growth exponent/coefficient (EGE/EGC);finite-time Lyapunov exponent (FLE); experiment

Address
Yuchun Li, Hongliang Gou, Long Zhang and Chenyu Chang : Department of Hydraulic Engineering, College of Civil Engineering, Tongji University, Shanghai, China

Abstract
This paper presents an experimental investigation on the contribution of RCC strip in the in-filled RC frames. In this research, two frames were tested to study the behavior of retrofitted RC frame under cyclic loading. In the two frame, one was three bay four storey R.C frame with central bay brick infill with RCC strip in-between brick layers and the other was retrofitted frame with same stiffened brick work. Effective rehabilitation is required some times to strengthened the RC frames. Ferrocement concrete strengthening was used to retrofit the frame after the frame was partially collapsed. The main effects of the frames were investigated in terms of displacement, stiffness, ductility and energy dissipation capacity. Diagonal cracks in the infill bays were entirely eliminated by introducing two monolithic RCC strips. Thus more stability of the frame was obtained by providing RCC strips in the infill bays. Load carrying capacity of the frame was increased by enlarging the section in the retrofitted area.

Key Words
RCC strip; Ferro-cement retrofit; load-displacement; stiffness; ductility; energy dissipation; load carrying capacity

Address
Suyamburaja Arulselvan : Department of Civil Engineering, Coimbatore Institute of Technology, Civil Aerodrome Post, Coimbatore-641014, Tamilnadu, India
P. Sathiaseelan: Department of Civil Engineering, PPG Institute of Technology, Saravanampatti, Coimbatore-641035, Tamilnadu, India

Abstract
In the present paper, the effects of cutting parameters and coating material on the performances of cutting tools in turning of AISI 52100 steel are discussed experimentally. A comparative study was carried out between uncoated and coated (with TiCN-TiN coating layer) cermet tools. The substrate composition and the geometry of the inserts compared were the same. A mathematical model was developed based on the Response Surface Methodology (RSM). ANOVA method was used to quantify the effect of cutting parameters on the machining surface quality and the cutting forces. The results show that feed rate has the most effect on surface quality. However, cutting depth has the significant effect on the cutting force components. The effect of coating layers on the surface quality was also studied. A lower surface roughness was observed when using PVD (TiCN-TiN) coated insert. A second order regression model was developed and a good accuracy was obtained with correlation coefficients in the range of 95% to 97%.

Key Words
coating material; cutting tool; mathematical model; RSM; ANOVA; machining surface; cutting forces

Address
Ouahid Keblouti, Lakhdar Boulanouar and Mohamed Walid Azizi : Advanced Technologies in Mechanical Production Research Laboratory (LRTAPM), Badji Mokhtar-Annaba University,
BP 12 Annaba 23000, Algeria
Mohamed Athmane Yallese : Mechanics and Structures Research Laboratory (LMS), May 8th 1945 University, PO Box 401, Guelma 24000, Algeria

Abstract
The evaluation of the loss-of-support conditions of frictional beam-to-column connections using simplified numerical models describing the transverse response of a portal-like structure is presented in this paper considering the effects of the seismic-hazard disaggregation. Real earthquake time histories selected from European Strong-motion Database (ESD) are used to show the effects of the seismic-hazard disaggregation on the beam loss-of-support conditions. Seismic events are classified according to different values of magnitudes, epicentral distances and soil conditions (stiff or soft soil) highlighting the importance of considering the characteristics of the seismic input in the assessment of the loss-of-support conditions of frictional beam-to-column connections. A rigid and an elastic model of a frame of a precast industrial building (2-DoF portal-like model) are presented and adopted to find the minimum required friction coefficient to avoid sliding. Then, the mean value of the minimum required friction coefficient with an epicentral distance bin of 10 km is calculated and fitted with a linear function depending on the logarithm of the epicentral distance. A complete parametric analysis varying the horizontal and vertical period of vibration of the structure is performed. Results show that the loss-of-support condition is strongly influenced by magnitude, epicentral distance and soil conditions determining the frequency content of the earthquake time histories and the correlation between the maxima of the horizontal and vertical components. Moreover, as expected, dynamic characteristics of the structure have also a strong influence. Finally, the effect of the column nonlinear behavior (i.e. formation of plastic hinges at the base) is analyzed showing that the connection and the column are a series system where the maximum force is limited by the element having the minimum strength. Two different longitudinal reinforcement ratios are analyzed demonstrating that the column strength variation changes the system response.

Key Words
loss of support; disaggregation; friction coefficient; precast industrial buildings; beam-to-column connections

Address
Cristoforo Demartino and Giorgio Monti : College of Civil Engineering, Nanjing Technical University, Nanjing 211816, PR China / DISG, Sapienza University of Rome, via A. Gramsci 53, 00197 Rome, Italy
Ivo Vanzi : Department of Engineering and Geology, University \"G. d\'Annunzio\" of Chieti-Pescara, viale Pindaro, 42 65127 Pescara, Italy / College of Civil Engineering, Fuzhou University, Fuzhou, 350108 Fujian, China

Abstract
In this paper, the wave propagation in an infinite poroelastic cylindrical bone with cavity is studied. An exact closed form solution is presented by employing an analytical procedure. The frequency equation for poroelastic bone is obtained when the boundaries are stress free and is examined numerically. The magnitude of the frequency equation, wave velocity and attenuation coefficient are calculated for poroelastic bone for different values of magnetic field, density and frequency. In wet bone little frequency dispersion was observed, in contrast to the results of earlier studies. Such a model would in particular be useful in large-scale parametric studies of bone mechanical response. Comparison was made with the results obtained in the presence and absence of magnetic field. The results indicate that the effect of magnetic field, density and frequency on wave propagation in poroelastic bone are very pronounced.

Key Words
wave propagation; poroelastic; wet bone; magnetic field; natural frequency

Address
A.M. Farhan : Physics Department, Faculty of Science, Jazan University, Jazan, Saudi Arabia / Physics Department, Faculty of Science, Zagazig University, Zagazig, Egypt

Abstract
As FGM (functionally graded material) bars which vibrate in axial or longitudinal direction have great potential for applications in diverse engineering fields, developing a reliable mathematical model that provides very reliable vibration and wave characteristics of a FGM axial bar, especially at high frequencies, has been an important research issue during last decades. Thus, as an extension of the previous works (Hong et al. 2014, Hong and Lee 2015) on three-layered FGM axial bars (hereafter called FGM bars), an enhanced spectral element model is proposed for a FGM bar model in which axial and radial displacements in the radial direction are treated more realistic by representing the inner FGM layer by multiple sub-layers. The accuracy and performance of the proposed enhanced spectral element model is evaluated by comparison with the solutions obtained by using the commercial finite element package ANSYS. The proposed enhanced spectral element model is also evaluated by comparison with the author

Key Words
functionally graded material (FGM); three-layered FGM axial bar; spectral element method; dynamic responses; waves

Address
Minsik Lee, Ilwook Park and Usik Lee : Department of Mechanical Engineering, Inha University, Inha-ro 100, Nam-gu, Incheon 22212, Republic of Korea


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