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CONTENTS
Volume 29, Number 1, May10 2008
 

Abstract
Tunnels are generally constructed below the ground water table, which produces a long-term interaction between the tunnel lining and the surrounding geo-materials. Thus, in conjunction with tunnel design, the presence of water may require a number of considerations such as: leakage and water load. It has been reported that deterioration of a drainage system of tunnels is one of the main factors governing
the long-term hydraulic and structural lining-ground interaction. Therefore, the design procedure of an underwater tunnel should address any detrimental effects associated with this interaction. In this paper an attempt to identify the coupled structural and hydraulic interaction between the lining and the ground was made using a numerical method. A main concern was given to local hindrance of flow into tunnels. Six cases of local deterioration of a drainage system were considered to investigate the effects of deterioration on tunnels. It is revealed that hindrance of flow increased pore-water pressure on the deteriorated areas, and caused detrimental effects on the lining structures. The analysis results were compared with those from fully permeable and impermeable linings.

Key Words
tunnel lining; hydraulic deterioration; coupled structural and hydraulic interaction.

Address
J. H. Shin: Dept. of Civil Engineering, Konkuk University, Korea

Abstract
Neglecting the real joint behaviour in frame analysis may result in unrealistic predictions of the response and reliability of steel frames. The reliability of the prediction of main joint properties according to the component method (Eurocode 3-Part 1.8) still remains open to further investigation. The first step toward the solution is to compare the theoretical expressions given in EN 1993-1-8 and the experimental results. With that goal in mind six nominally the same, but really different specimens of welded beam-to-column joints subjected to static load were tested. The specimens present a combination of nominally identical structural elements produced in different European mills. This paper provides these tests, as well as their detailed evaulation and interpretation. All three joint structural properties (rotational stiffness, moment resistance and rotation capacity) have been considered. Four models for determining the plastic resistance out of experimental Mj-? curves have been applied. The results that have been discussed in detail, point to the fact that EN 1993-1-8 underestimates the real structural properties of the tested type of joint, as well as to the conclusion that detailed research of this problem needs to be conducted using the probabilistic reliability methods.

Key Words
semi rigid joint; rotational stiffness; moment resistance; rotation capacity; Eurocode 3-Part 1.8; experimental testing; reliability.

Address
Davor Skejic, Darko Dujmovic and Boris Androic: Dept. of Structural Engineering, Faculty of Civil Engineering, University of Zagreb Kaciceva 26, 10000 Zagreb, Croatia

Abstract
Plane steel portal frames, with pitched roof, exposed to fire, are examined. First, a determinate frame is analysed by hand. For flexible columns and shallow roof, snap-through occurs before plastic hinges mechanism is formed. An indeterminate frame with shorter columns and taller roof is also analysed by hand. Then, the same frame is simulated by a truss and a nonlinear static analysis is performed by use of a short computer program. The results of computer analysis by use of truss model are compared with those of analysis by hand and a satisfactory approximation between them is observed.

Key Words
steel portal frame; pitched roof; fire; snap-through; plastic hinges; truss model.

Address
Panagis G. Papadopoulos, Anastassia K. Papadopoulou and Kyriakos K. Papaioannou: Dept. of Civil Engineering, Aristotle University of Thessaloniki, 540 06 Thessaloniki, Greece

Abstract
In this paper, the behavior of two collinear Mode-I cracks in piezoelectric/piezomagnetic materials subjected to a uniform tension loading was investigated by the generalized Almansi?s theorem.
Through the Fourier transform, the problem can be solved with the help of two pairs of triple integral equations, in which the unknown variables were the jumps of displacements across the crack surfaces. To
solve the triple integral equations, the jumps of displacements across the crack surfaces were directly expanded as a series of Jacobi polynomials to obtain the relations among the electric displacement
intensity factors, the magnetic flux intensity factors and the stress intensity factors at the crack tips. The interaction of two collinear cracks was also discussed in the present paper.

Key Words
crack; piezoelectric/piezomagnetic materials; Fourier integral transform.

Address
Zhen-Gong Zhou, Jia-Zhi Wang and Lin-Zhi Wu: P. O. Box 3010, Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin, 150080, P. R. China

Abstract
Presence of high degree of orthotropy enhances shear lag phenomenon in laminated composite box-beams and it persists till failure. In this paper three key parameters governing shear lag behavior of laminated composite box beams are identified and defined by simple expressions. Uniqueness of the identified key parameters is proved with the help of finite element method (FEM) based studies. In addition to this, for the sake of generalization of prediction of shear lag effect in symmetrical laminated composite box beams a feed forward back propagation neural network (BPNN) model is developed. The network is trained and tested using the data base generated by extensive FEM studies carried out for various b/D, b/tF, tF/tW and laminate configurations. An optimum network architecture has been established which can effectively learn the pattern. Computational efficiency of the developed ANN makes it suitable for use in optimum design of laminated composite box-beams.

Key Words
laminated composites; shear lag; effective width ratio; finite element method; artificial neural networks.

Address
Rajeev Chandak, Akhil Upadhyay and Pradeep Bhargava:
Dept. of Civil Engineering, Indian Institute of Technology, Roorkee, 247667, India

Abstract
This paper outlines the development of a computational model in order to analyze the dynamic behaviour of coupled fluid-structure systems such as a) liquid containers, b) a set of parallel or
radial plates. In this work a hybrid fluid-solid element is developed, capable of simulating both membrane and bending effects of the plate. The structural mass and stiffness matrices are determined using exact integration of governing equations which are derived using a combination of classical plate theory and a finite element approach. The Bernoulli equation and velocity potential function are used to describe the liquid pressure applied on the solid-fluid element. An impermeability condition assures a permanent contact at the fluid-structure interface. Applications of this model are presented for both parallel and radial plates as well as fluid-filled rectangular reservoir. The effect of physical parameters on the dynamic behaviour of a coupled fluid-structure system is investigated. The results obtained using the presented approach for dynamic characteristics such as natural frequency are in agreement to those calculated using other theories and experiments.

Key Words
plates and shells; added mass; vibration; fluid-solid element.

Address
Y. Kerboua and A.A. Lakis: Mechanical Engineering Department, Ecole Polytechnique de Montreal, C.P. 6079, Succursale Centre-ville, Montreal, Quebec, H3C 3A7, Canada
M. Thomas: Mechanical Engineering Department, Ecole de Technologie Superieure, 1100 Notre Dame Ouest Montreal, Quebec, H3C 1K3, Canada
L. Marcouiller: Institut de Recherche d?Hydro Quebec, 1800 Lionel-Boulet, Varennes, Quebec, J3X 1S1, Canada

Abstract
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Key Words
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Address
Brad Regez, Ying Zhang, Tsuchin Chu, Jarlen Don and Ajay Mahajan: Dept. of Mechanical Engineering and Energy Processes, Southern Illinois University at Carbondale Carbondale, IL 62901-6603, U.S.A.


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