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CONTENTS
Volume 31, Number 4, March 10 2009
 

Abstract
The concrete plates are most widely used structural elements in the hulls of floating concrete structures such as concrete barges and pontoons, bridge decks, basement floors and liquid storage tanks. The study on the behavior of high-strength fiber reinforced concrete (HSFRC) plates was carried out to evaluate the performance of plates under in-plane and transverse loads. The plates were tested in simply supported along all the four edges and subjected to in-plane and traverse loads. In this experimental program, twenty four 150 mm diameter cylinders and twelve plate elements of size 600

Key Words
steel fiber reinforced concrete; silica fume; steel fibers; static mechanical properties; axial loads; plate elements; out-of-plane central deflection.

Address
Ramadoss, P.: Department of Civil Engineering, Pondicheery Engineering College, Puducherry-605 014, India
Nagamani, K.: Structural Engineering Division, Civil Engineering Department, Anna University, Chennai-600 025, India

Abstract
The static and dynamic analyses of simply supported beams are studied by using the Utransformation method and the finite difference method. When the beam is divided into the mesh of equal elements, the mesh may be treated as a periodic structure. After an equivalent cyclic periodic system is established, the difference governing equation for such an equivalent system can be uncoupled by applying the U-transformation. Therefore, a set of single-degree-of-freedom equations is formed. These equations can be used to obtain exact analytical solutions of the deflections, bending moments, buckling loads, natural frequencies and dynamic responses of the beam subjected to particular loads or excitations. When the number of elements approaches to infinity, the exact error expression and the exact convergence rates of the difference solutions are obtained. These exact results cannot be easily derived if other methods are used instead.

Key Words
static analysis; dynamic analysis; beam; convergence rate; U-transformation; finite difference method.

Address
Y. Yang: School of Civil Engineering and Transportation, South China University of Technology, Guangzhou, 510640, P. R. China
M. Cai and J. K. Liu: Department of Mechanics, Zhongshan University, Guangzhou 510275, P. R. China

Abstract
The Purpose of this paper is to show the applicability of a methodology, developed by the authors, with which to perform the mechanical optimization of space truss structures strongly restricted. This methodology use a parameter call \"Volumetric Displacement\", as the Objective Function of the optimization process. This parameter considers altogether the structure weight and deformation whose effects are opposed. The Finite Element Method is employed to calculate the stress/strain state and the natural frequency of the structure through a structural linear static and natural frequency analysis. In order to show the potentially of this simple methodology, its application on a large diameter telescope structure (10 m) considering the strongly restriction that became of its use, is presented. This methodology, applied in previous works on continuous structures, such as shell roof and fluid storage vessels, is applied in this case to a space truss structure, with the purpose of generalize its applicability to different structural topology. This technique could be useful in the morphology design of deployable and retractable roof structures, whose use has extensively spread in the last years.

Key Words
structural analysis; optimization; telescope.

Address
Nestor F. Ortega and Sandra I. Robles: Departamento de Ingenieria - Universidad Nacional del Sur-Av. Alem 1253,(8000) Bahia Blanca, Argentina

Abstract
The present paper addresses the optimal design of composite laminates with the aim of minimizing free-edge delamination stresses. A technique involving the application of particle swarm optimization (PSO) integrated with FEM was developed for the optimization. Optimization was also conducted with the zero-order method (ZOM) included in ANSYS. The semi-analytical method, which provides an approximation of the interlaminar normal stress of laminates under in-plane load, was used to partially validate the optimization results. It was found that optimal results based on ZOM are sensitive to the starting design points, and an unsuitable initial design set will lead to a result far from global solution. By contrast, the proposed method can find the global optimal solution regardless of initial designs, and the solutions were better than those obtained by ZOM in all the cases investigated.

Key Words
laminates; interlaminar stress; particle swarm optimization; delamination; FEM.

Address
Jianqiao Chen, Wenjie Peng, Rui Ge and Junhong Wei: Department of Mechanics, Huazhong University of Science and Technology, Wuhan 430074, China

Abstract
In order to perform a step-by-step force-displacement response analysis or dynamic timehistory analysis of large buildings with masonry infilled R/C frames, a continuous force-deformation model based on an equivalent strut approach is proposed for masonry infill panels containing openings. The model, which is applicable for degrading elements, can be implemented to replicate a wide range of monotonic force-displacement behaviour, resulting from different design and geometry, by varying the control parameters of the model. The control parameters of the proposed continuous model are determined using experimental data. The experimental program includes fifteen 1/3-scale, single-story, single-bay reinforced concrete frame specimens subjected to lateral cyclic loading. The parameters investigated include the shape, the size, the location of the opening and the infill compressive strength. The actual properties of the infill and henceforth the characteristics needed for the diagonal strut model are based on the assessment of its lateral resistance by the subtraction of the response of the bare frame from the response of the infilled frame.

Key Words
infilled R/C frames; masonry infills; openings; experimental results; analytical modeling.

Address
D. Kakaletsis: Technological Educational Institution of Serres, Terma Magnesias, Serres, 62124, Greece

Abstract
The paper deals with the problem related to the modelling of riveted assemblies for crashworthiness analysis of full-scale complete aircraft structures. Comparisons between experiments and standard FE computations on high-energy accidental situations onto aluminium riveted panels show that macroscopic plastic strains are not sufficiently localised in the FE shells connected to rivet elements. The main reason is related to the structural embrittlement caused by holes, which are currently not modelled. Consequently, standard displacement FE models do not succeed in initialising and propagating the rupture in sheet metal plates and along rivet rows as observed in the experiments. However, the literature survey show that it is possible to formulate super-elements featuring defects that both give accurate singular strain fields and are compatible with standard displacement finite elements. These super-elements can be related to the displacement model of the hybrid-Trefftz principle of the finite element method, which is a kind of domain decomposition method. A feature of hybrid-Trefftz finite elements is that they are mainly used for elastic computations. It is thus proposed to investigate the possibility of formulating a hybrid displacement finite element, including the effects of a hole, dedicated to crashworthiness analysis of fullscale aeronautic structures.

Key Words
hybrid-displacement finite element; complex variable; structural mechanics; riveted assemblies; crashworthiness.

Address
Nicolas Leconte and Bertrand Langrand: Department of Aeroelasticity and Structural Dynamics, The French Aerospace Lab (ONERA),F-59045 Lille, France
Eric Markiewicz: Laboratory of Industrial and Human Automation Control, Mechanical Engineering and Computer Science (LAMIH UMR CNRS 8530), University of Valenciennes, F-59313 Valenciennes, France

Abstract
The literature regarding the free vibration analysis of Bernoulli-Euler and Timoshenko beams on elastic soil is plenty, but the free vibration analysis of Reddy-Bickford beams on elastic soil with/without axial force effect using the Differential Transform Method (DTM) has not been investigated by any of the studies in open literature so far. In this study, the free vibration analysis of axially loaded Reddy-Bickford beam on elastic soil is carried out by using DTM. The model has six degrees of freedom at the two ends, one transverse displacement and two rotations, and the end forces are a shear force and two end moments in this study. The governing differential equations of motion of the rectangular beam in free vibration are derived using Hamilton

Key Words
differential transform method; elastic soil; free vibration; partial differential equation; Reddy-Bickford beam.

Address
Yusuf Yesilce and Seval Catal: Dokuz Eylul University, Civil Engineering Department, Engineering Faculty, 35160, Buca, Izmir, Turkey

Abstract
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Key Words
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Address
Murat Reis and Yasar Pala: Uluda University, Engineering Faculty, Mechanical Engineering Department, Gorukle,16059, Bursa, Turkey


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