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NUMERICAL CREEP BUCKLING ANALYSIS OF BEAM-TYPE STRUCTURES
Domagoj Lanc
; Faculty of Engineering, University of Rijeka, Rijeka, Croatia
Abstract
In this work a numerical stability analysis of materially nonlinear beam framed structures is presented. An numerical algorithm using one dimensional spatial beam finite element is developed. Beam members are suppose to be straight and prismatic and of rectangular cross section. Spatial displacements and rotations are allowed to be large but strains are assumed to be small. The corresponding equilibrium equations are formulated in the framework of Eulerian description, using the virtual work principle. Euler-Bernoully beam theory for flexure is assumed as well as Saint-Venant theory for torsion. In contrast to conventional Eulerian formulation, which is linear on element level, and unable to model Wagner effect in this paper an additional nonlinear part of stiffness matrix is evaluated and added to standard elastic stiffness.
Problem is approached through two phases. In first phase a pre-buckling behavior is modeled through load deflection manner to reach appropriate instantaneous response of structure for applied load at zero moment while in second phase an explicit time integration scheme is used to reach critical buckling time. Plastic material behavior is modeled supposing isotropic hardening law while for modeling creep material behavior Norton and Nutting laws have been applied. Isothermal conditions during creep are supposed. An own computer program BMCA is developed and his implementation is demonstrated on some test examples.
Keywords
stability; beam-type structures; large rotations; material non-linearity; creep
Hrčak ID:
28407
URI
Publication date:
27.12.2006.
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