Techno Press
Tp_Editing System.E (TES.E)
Login Search


scs
 
CONTENTS
Volume 17, Number 1, July 2014
 

Abstract
Buckling and vibration characteristics of circular laminated plates under in-plane edge loads and resting on Winkler-type foundation are solved by the Ritz method. Inclusive numerical data are presented for the first three eigen-frequencies as a function of in-plane load for different classical edge conditions. Moreover, the effects of fiber orientation on the natural frequencies and critical buckling loads of laminated angle-ply plates with stacking sequence of [(β / -β / β / -β)]s, are studied. Also, selected deformation mode shapes are illustrated. The correctness of results is established using finite element software as well as by comparison with the existing results in the literature.

Key Words
natural vibrations; buckling loads; composite laminates; elastic foundation; variational method; in-plane force

Address
School of Mechanical Engineering, Iran University of Science and Technology, Tehran, 16846-13114, Iran.

Abstract
This paper presents a simple n-order four variable refined theory for the bending and vibration analyses of functionally graded plates. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The present theory is variationally consistent, uses the n-order polynomial term to represent the displacement field, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The governing equations are derived by employing the Hamilton\'s principle and the physical neutral surface concept. The accuracy of the present solutions is verified by comparing the obtained results with available published ones.

Key Words
nth-order four variable refined theory; FG plates; vibration; bending; neutral surface position

Address
(1) I. Klouche Djedid, Abdelkader Benachour, Abdelouahed Tounsi:
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(2) I. Klouche Djedid:
Universitée Ibn Khaldoun, BP 78 Zaaroura, 14000 Tiaret, Algeria;
(3) Mohammed Sid Ahmed Houari, Abdelouahed Tounsi, Mohammed Ameur:
Laboratoire des Structures et Matéeriaux Avancés dans le Genie Civil et Travaux Publics, Universitée de Sidi Bel Abbes, Facultée de Technologie, Algeria;
(4) Mohammed Ameur:
Ecole Nationale Polytechnique d\'Oran, Algeria.

Abstract
Due to thermal expansion, the structural behaviour of beams in steel structures subjected to temperature increase will be affected. This may result in the failure of the structural members or connection due to extra internal force in the beam induced by the thermal increase. A method to release some of the thermally generated internal force in the members is to allow for some movements at the end supports of the member. This can be achieved by making the plane of the end-plate of the connection slanted instead of vertical as in conventional design. The present paper discusses the mechanical behaviour of beams with bolted slant end-plate connection under symmetrical gravity loads, subjected to temperature increase. Analyses have been carried out to investigate the reduction in internal force with various angles of slanting, friction factor at the surface of the connection, and allowable temperature increase in the beam. The main conclusion is that higher thermal increase is tolerable when slanting connection is used, which means the risk of failure of structures can be reduced.

Key Words
slant bolted end-plate connection; elevated-temperature; symmetric gravity load; friction factor; friction bolt; analytical model

Address
(1) F. Zahmatkesh, M.H. Osman, E. Talebi:
Faculty of Civil Engineering at Universiti Teknologi Malaysia (UTM), 81310 UTM, Johor, Malaysia;
(2) A.B.H. Kueh:
Construction Research Centre (CRC), Universiti Teknologi Malaysia (UTM), 81310 UTM, Johor, Malaysia.

Abstract
The novelty of this paper is the use of trigonometric four variable plate theory for free vibration analysis of laminated rectangular plate supporting a localized patch mass. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The Hamilton's Principle, using trigonometric shear deformation theory, is applied to simply support rectangular plates. Numerical examples are presented to show the effects of geometrical parameters such as aspect ratio of the plate, size and location of the patch mass on natural frequencies of laminated composite plates. It can be concluded that the proposed theory is accurate and simple in solving the free vibration behavior of laminated rectangular plate supporting a localized patch mass.

Key Words
laminated plates; free vibration; four variable plate theory; patch mass

Address
(1) Kada Draiche, Abdelouahed Tounsi, Y. Khalfi:
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(2) Abdelouahed Tounsi:
Laboratoire des Structures et Matériaux Avancés dans le Génie Civil et Travaux Publics, Université de Sidi Bel Abbes, Faculté de Technologie, Département de génie civil, Algeria.

Abstract
The objective of this research is to study the ultimate moment capacity of the connections between steel I-beams and concrete-filled steel tube columns using different stiffener configurations. The main parameters considered are column cross section shape, square or circular, and filling the column with concrete. This analytical study includes finite element models using ANSYS program taking geometric and material nonlinearities into consideration. These models are verified against the experimental results obtained from previous researches and current design guides. The results show that using proper stiffener configuration affects the stress distribution through the connection and increases the ultimate moment capacity of the connections. Also, circular column is advantageous than the square column for all stiffener configurations and dimensions.

Key Words
concrete-filled steel tubes; square columns; circular columns; finite element analysis; stiffener configurations; ultimate strength; moment connections

Address
Structural Engineering Department, Faculty of Engineering, Ain Shams University, Egypt.

Abstract
A fundamental limitation of steel structures is the decrease in their load-bearing capacity at high temperatures in fire situations such that structural members may require some additional treatment for fire resistance. In this regard, this paper evaluates the structural stability of fire-resistant steel, introduced in the late 1999s, through tensile coupon tests and proposes some experimental equations for the yield stress, the elastic modulus, and specific heat. The surface temperature, deflection, and maximum stress of fire-resistant steel H-section columns were calculated using their own mechanical and thermal properties. According to a comparison of mechanical properties between fire-resistant steel and Eurocode 3, the former outperformed the latter, and based on a comparison of structural performance between fire-resistant steel and ordinary structural steel of equivalent mechanical properties at room temperature, the former had greater structural stability than the latter through 900°C.

Key Words
fire-resistant steel; FR490 steel; mechanical property; thermal property; stability; structural performance

Address
(1) In-Kyu Kwon:
Department of Fire Protection Engineering, Kangwon National University, 243 Joongangro, Samcheok-si, Kangwon Province, South Korea;
(2) Young-Bong Kwon:
Department of Civil Engineering, Yeungnam University, 280, Daehak-ro, Gyeongsan-si, Gyeongsangbuk-do, South Korea.

Abstract
In this paper we have considered the vibration of parametrically excited oscillator with strong cubic positive nonlinearity of complex variable in nonlinear dynamic systems with forcing based on Mathieu-Duffing equation. A new analytical approach called homotopy perturbation has been utilized to obtain the analytical solution for the problem. Runge-Kutta's algorithm is also presented as our numerical solution. Some comparisons between the results obtained by the homotopy perturbation method and Runge-Kutta algorithm are shown to show the accuracy of the proposed method. In has been indicated that the homotopy perturbation shows an excellent approximations comparing the numerical one.

Key Words
Homotopy Perturbation Method (HPM); Runge-Kutta Method (RKM); parametrically excited oscillator

Address
(1) Mahdi Bayat, Mahmoud Bayat:
Department of Civil Engineering, College of Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran;
(2) Iman Pakar:
Young Researchers and Elites Club, Mashhad Branch, Islamic Azad University, Mashhad, Iran.

Abstract
In this paper, we try to prepare an accurate analytical solution for solving nonlinear vibration of thin circular sector cylinder. A new approximate solution called variational approach is presented and correctly applied to the governing equation of thin circular sector cylinder. The effect of important parameters on the response of the problem is considered. Some comparisons have been presented between the numerical solution and the present approach. The results show an excellent agreement between these methods. It has been illustrated that the variational approach can be a useful method to solve nonlinear problems by considering the effects of important parameters.

Key Words
thin circular sector cylinder; nonlinear vibration; variational approach

Address
(1) Iman Pakar:
Young Researchers and Elites Club, Mashhad Branch, Islamic Azad University, Mashhad, Iran;
(2) Mahmoud Bayat, Mahdi Bayat:
Department of Civil Engineering, College of Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran.


Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2017 Techno-Press
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Tel: +82-42-828-7996, Fax : +82-42-828-7997, Email: info@techno-press.com