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Civil-Comp Proceedings
ISSN 1759-3433 CCP: 88
PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and M. Papadrakakis
Paper 13
Evaluation of the Buckling Critical Load of Bars Subjected to their Self-Weight A.M. Wahrhaftig, R.M.L.R.F. Brasil and M.A.S. Machado
Department of Structural and Geotechnical Engineering, Polytechnic School, University of São Paulo, Brazil A.M. Wahrhaftig, R.M.L.R.F. Brasil, M.A.S. Machado, "Evaluation of the Buckling Critical Load of Bars Subjected to their Self-Weight", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 13, 2008. doi:10.4203/ccp.88.13
Keywords: critical load, elastic stability, geometric stiffness, finite element method, buckling, self-weight.
Summary
The consideration of the bar self-weight in the buckling critical load problem was
first discussed by Euler, who could not obtain a satisfactory solution. This problem
was definitely solved by Greenhill in 1881. The main difficulty found by Euler was
that the differential equation for the curvature considering a uniformly distributed
compressive force is not as simple as the constant coefficients of the differential
equation for the normal external force buckling problem [1]. The solution of first
case requires either the application of infinite series or the application of
approximate methods (e.g. the energy method). Modern procedures utilize matrix
linear analyses based on a non-trivial solution by eigenvalues and eigenvectors, and
offer numerical solutions easily implemented using a finite element (FE)
environment [2]. However, it is important to understand that the stiffness matrix of
structures subjected to axial loads is different from the conventional stiffness matrix.
Axial loads produce the effect of reducing the stiffness of the structural members [3]. Hence, the buckling critical load determination now requires some of the aspects
peculiar to non-linear analysis. That can be conveniently done, for several
engineering problems, by the introduction of the geometric stiffness concept [4]. He
present work evaluates the critical load of bars exclusively subjected to their
self-weight, utilizing Euler's formulation and the finite element method eigenvalue
solution via computational analysis.
References
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