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CONTENTS
Volume 6, Number 7, October 1998
 

Abstract
Finite element models and numerical results are presented for bending and natural vibration using the unified third-order plate theory developed in Part 1 of this paper. The unified third-order theory contains the classical, first-order, and other third-order plate theories as special cases. Analytical solutions are developed using the Navier and Levy solution procedures (see Part 1 of the paper). Displacement finite element models of the unified third-order theory are developed herein. The finite elelment models are based on C-0 interpolation of the inplane displacements and rotation functions and C-1 interpolation of the transverse deflection. Numerical results of bending and natural vibration are presented to evaluate the accuracy of various plate theories.

Key Words
finite element model, analytical solutions, bending, vibration, shear deformation, third-order theory

Address
Bose P, Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA
Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA

Abstract
In this paper the influence of rotary inertia, shear and compressibility on the value of the critical force for the Beck\'s column is analyzed. The constitutive equation is of Engesser\'s type. As a result, the critical load parameter for which instability of flutter type occurs is calculated for several values of the column\'s parameters.


Key Words
beck\'s column, elastic stability, column with shear and compressibility

Address
Cveticanin LJ, Dept Tech Sci, Trg D Obradovica 6, YU-21000 Novi Sad, Yugoslavia
Dept Tech Sci, YU-21000 Novi Sad, Yugoslavia

Abstract
The objective of the present work is to estimate the strength and failure characteristics of symmetric thin square laminates under negative shear load. Two progressive failure analyses, one using the Hashin criterion and the other using a Tensor polynomial criterion, are used in conjunction with the finite element method. First-order shear-deformation theory along with geometric nonlinearity in the von Karman sense has been incorporated in the finite element modeling. Failure loads, associated maximum transverse displacements, locations and modes of failure including the onset of delamination are discussed in detail; these are found to be quite different from those for the positive sheer load reported in Part I of this study (Singh et al. 1998).

Key Words
progressive failure, laminated plate, failure criteria, in-plane negative shear

Address
Singh SB, MNREC, Dept Appl Mech, Allahabad, Uttar Pradesh, India
Indian Inst Technol, Dept Civil Engn, Kanpur 208016, Uttar Pradesh, India
Indian Inst Technol, Dept Aerosp Engn, Kanpur 208016, Uttar Pradesh, India

Abstract
To assess the collapse risk of transmission line structures subject to natural hazards, it is important to identify what hazard may cause the structural collapse. In Australia and many other countries, a large proportion of failures of transmission line structures are caused by severe thunderstorms. Because the wind loads generated by thunderstorms are not only random but time-variant as well, a time-dependent structural reliability approach for the risk assessment of transmission line structures is essential. However, a lack of appropriate stochastic models for thunderstorm winds usually makes this kind of anaysis impossible. The intention of the paper is to propose a stochastic model that could realistically and accurately simulate wind loading due to severe thunderstorms. With the proposed thunderstorm model, the collapse risk of transmission line structures under severe thunderstorms is assessed numerically based on the computed failure probability of the structure.

Key Words
risk, failure probability, transmission line, thunderstorms, wind loads, stochastic model, poisson process, upcrossing rate

Address
Li CQ, Monash Univ, Dept Civil Engn, Clayton, Vic 3145, Australia
Monash Univ, Dept Civil Engn, Clayton, Vic 3145, Australia

Abstract
This paper deals with the nonlinear finite element analysis of fibre-reinforced plastic poles. Based on the principle of stationary potential energy and Novozhilov\'s derivations of nonlinear strains, the formulations for the geometric nonlinear analysis of general shells are derived. The formulations are applied to the fibre-reinforced plastic poles which are treated as conical shells. A semi-analytical finite element model based on the theory of shell of revolution is developed. Several aspects of the implementation of the geometric nonlinear analysis are discussed. Examples are presented to show the applicability of the nonlinear analysis to the post-buckling and large deformation of fibre-reinforced plastic poles.

Key Words
nonlinear analysis, finite element, stability, large displacement, fibre-reinforced plastics, poles

Address
Lin ZM, Univ Manitoba, Dept Civil & Geol Engn, Winnipeg, MB, Canada
Univ Manitoba, Dept Civil & Geol Engn, Winnipeg, MB, Canada

Abstract
An overview of an analytical model to predict mortar joint failure in unreinforced masonry (URM) structures is presented. The validity of the model is established by comparison with experimental results at element level as well as structure level. This model is then used to study the behavior of URM walls and two commonly used retrofitting schemes. Finally, effectiveness of the two retrofitting schemes in increasing strength and stiffness of existing URM walls is discussed.

Key Words
masonry waus, seismic, mortar, joint, interface, retrofitting

Address
Mehta S, Lichtenstein Engn Associates, 350 5th Ave, New York, NY 10118 USA
Lichtenstein Engn Associates, New York, NY 10118 USA
New Jersey Inst Technol, Dept Civil & Environm Engn, Newark, NJ 07102 USA

Abstract
A finite element model based on the incremental endochronic theory for flexible pavement materials was developed in this study. Three grid systems with eight-node cubic isoparametric elements, and different loading steps were used to perform the calculations for a specimen of circular cylinder. The uniaxial stress experimental results on an asphalt mixture at 60 degrees C in SHRP conducted by University of California at Berkeley were used to check the ability of the derived numerical model. Then, the numerical results showed isotropic response and deviatoric response on the specimen in a three dimensional manner, which provided a better understanding for a deformed flexible material under the specified loading conditions.

Key Words
finite element analysis, incremental endochronic theory, flexible pavement material, isotropic response, deviatoric response

Address
Kerh T, Natl Pingtung Univ Sci & Technol, Dept Civil Engn, Pingtung 91207, Taiwan
Natl Pingtung Univ Sci & Technol, Dept Civil Engn, Pingtung 91207, Taiwan

Abstract
This paper presents a study of buckling of the multi-vaulted cylindrical shell (\"Aster\"), under an axial compression alone or combined with an external pressure. This shell which was presented in a recent paper is a self-stiffened structure having a satisfactory behaviour and a higher buckling strength under external pressure than a circular cylindrical shell with the same dimensions. The results of this study emphasize the interest of the behaviour of the \"Aster\" shell under two other types of loading, revealing an acceptable level of strength which is favorable for an expansion of its use in other areas.

Key Words
buckling, cylindrical shell, \"Aster\" shell, axial compression, external pressure, combined loading, self stiffening

Address
Araar M, Univ Annaba, Inst Civil Engn, BP 12, Annaba 23000, Algeria
Univ Annaba, Inst Civil Engn, Annaba 23000, Algeria
Inst Natl Sci Appl Lyon, F-69621 Villeurbanne, France


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