Finite element procedures for inelastic stability analysis of plated structures

Amit Dutta, Purdue University

Abstract

This research involves the development of improved capabilities for analysis of the inelastic stability of plated structures. The thesis addresses finite element, constitutive, and global solution aspects of the analysis. A primary goal of this research is the identification and elucidation of numerical difficulties associated with the finite element modeling of sensitive stability phenomena, and the development of procedures which alleviate these difficulties and improve upon the overall numerical performance. In the finite element component of the research, a three-node degenerate beam element is derived which accommodates warping due to torsional action in stocky plate components of rectangular cross-section. It is shown that warping displacements must be included in the formulation for adequate representation of the torsional behavior of these types of components. This element is combined with a nine-node shell finite element developed in prior research for the applications addressed in this work. With regard to the constitutive component of the present work, algorithms for integration of plasticity rate constitutive equations are investigated and improved upon for single-surface plasticity modeling, and the consistent linearization of these algorithms is developed in the context of both single- and multiple-surface plasticity models. At the global solution level, difficulties arising from bifurcation and severe limit point phenomena are investigated. An automated analysis system which efficiently and effectively traces the stability response of sensitive elastic and inelastic structures is formulated and implemented. The tools developed are applied specifically to achieve a better understanding of the full-range behavior of noncompact steel bridge plate girders.

Degree

Ph.D.

Advisors

White, Purdue University.

Subject Area

Civil engineering

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