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


sem
 
CONTENTS
Volume 2, Number 3, September 1994
 

Abstract
The purpose of this investigation is to propose a numerical simulation method of the crack propagation behavior in 3D elastic body. The simulation method is based on the displacement-type finite element method, and the linear fracture theory is introduced. The results from the proposed method are compared with those from the structural experiments, and the good coincidences between them are shown in this paper. At the same time, 2-dimensional analysis is also done, and the results are compared with those obtained from 3-dimensional analysis and the structural experiments.

Key Words
linear fracture theory ; FEM; 3D crack propagation; automatic mesh generation; singular isoparametric element.

Address
Eng. Science Department, Okayama University, Okayama, Japan
Japan Development and Construction Co. Ltd., Minatoku, Tokyo, Japan
Ishikawajima-Harima Heavy Industry Co., Kure-shi, Horoshima, Japan
Department of Civil Engineering, Okayama University, Okayama, Japan

Abstract
A new axisymmetric crack model is proposed on the basis of p-version of the finite element method limited to theory of small scale yielding. To this end, axisymmetric stress element is formulated by integrals of Legendre polynomial which has hierarchical nature and orthogonality relationship. The virtual crack extension method has been adopted to calculate the stress intensity factors for 3-D axisymmetric cracked bodies where the potential energy change as a function of position along the crack front is calculated. The sensitivity with respect to the aspect ratio and Poisson locking has been tested to ascertain the robustness of p-version axisymmetric element. Also, the limit value that is an exact solution obtained by FEM when degree of freedom is infinite can be estimated using the extrapolation equation based on error prediction in energy norm. Numerical examples of thick-walled cylinder, axisymmetric crack in a round bar and internal part-thorough cracked pipes are tested with high precision.

Key Words
axisymmetric p-version model; stress intensity factor; virtual crack extension method; robustness; error prediction; Poisson locking.

Address
Department of Civil Engineering, Chonnam National University
Kwangju 500-757, Korea

Abstract
Motions of an unsymmetric rigid body on a rigid floor subjected to earthquake excitations with special attention to coefficient of friction are investigated. Motions of a body in a plane are classified (Ishiyama 1980) into six types, i.e. (1) rest, (2) slide, (3) rotation. (4) slide rotation, (5) translation jump, (6) rotation jump. Based upon the theoretical and experimental research work special attention is paid to the sliding of a body. The equations of motions and the behavior of coefficient of friction in the time of floor excitation are studied. One of the features of this investigation is the introduction and estimation of the

Key Words
rigid usymmetric body; earthquake; motion; slide; time-dependent coefficient of friction.

Address
Elktroprojekt Ljubljana, Hajdrihova 4, Ljubljana 61000, Slovenia

Abstract
The analysis and tests of thin-walled channel frames including nonlinear flexible or semi-rigid connection behaviour is presented. The smi-rigid connection behaviour is modelled using a mathematical approximation of the connection flexibility-moment relationship. Local instability such as local buckling and torsional flexural buckling of the member are included in the analysis. The full response of the frame, up to the collapse load, can be predicted. Experimental investigation was carried out on a validity of the analysis. Agreement between the theoretical and experimental results is acceptable, The investigation also shows that connection flexibility and local instability such as local buckling and torsional flexural buckling can affect the behaviour and strength of thin-walled frames significantly. The results can also provide further insight into the advanced study of practical structures where interaction between flexible connections and phenomenon associated with thin-walled members are present.

Key Words
rigid usymmetric body; earthquake; motion; slide; time-dependent coefficient of friction.

Address
School of Mechanical and Production Engineering, Nanyang Technological University, Nanyang Avenue, 2263, Singapore

Abstract
Based on a fast and accurate method for the stationary random seismic response analysis for discretized structures(Lin 1992, Lin et al. 1992), a Ritz method for dealing with such responses of continuous systems in developed. This method is studied quantitatively, using cantilever shear beams for simplicity and clarity. The process can be naturally extended to deal with various boundary conditions as well as non-uniform Bernouli-Euler beams, or even Timoshenko beams. Algorithms for both proportionally and non-proportionally damped responses are described. For all of such damping cases, it is not necessary to solve for the natural vibrations of the beams. The solution procedure is very simple, and equally efficient for a white or a non-white ground excitation spectrum. Two examples are given where various power spectral density functions, variances, covariances and second spectral moments of displacement, internal force response, and their derivatives are calculated and analyses. Some Ritz solutions are compared with

Key Words
random seismic beam Ritz.

Address
Research Institute of Engineering Mechanics, Dalian University of Technology
Dalian, 116023, China
Division of Structural Engineering, University of Wales College of Cardiff, Cardiff CF2 1YF, UK

Abstract
The present paper concerns the mathematical study and the numerical treatment of the problem of semirigid connections in bolted steel column base plates by taking into account the possibility of appearance of separation phenomena on the contact surface under certain loading conditions. In order to obtain a convenient discrete form to simulate the structural behaviour of a steel column base plate, the continuous contact problem. By applying an appropriate finite element scheme, the discrete problem is formulated as a quadratic opimization problem which expresses, from the standponint of mechanics, the principle of minimum potential energy of the semirigid connection at eh state of equilibrium. For the numerical treatment of this problem, two effective and easy-to-use solution strategies based on quadratic optimization algorithms are proposed. This technique is illustrated by means of a numerical application.

Key Words
structural steel work; semirigid connections; column base plate; optimization.

Address
The Institute of Steel Structures, Department of Civil Engineering, Aristotle University, Thessaloniki 54006, Greece


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