Jurgen Becque

Numerical Investigation of the Interaction of Local and Overall Buckling of Stainless Steel I-Columns

This report describes research carried out at the University of Sydney to study the interaction of local and overall buckling in stainless steel I-columns. A finite-element model was constructed using the commercially available ABAQUS software package, taking into account the specific material properties of stainless steel: nonlinear stress-strain behavior, anisotropy, and enhanced corner properties as a result of cold working. The model was verified against the experimental data presented in the companion paper and yielded good predictions of the behavior and ultimate capacity of the test specimens. The finite-element model was subsequently used in parametric studies, which covered the practical ranges of overall and cross-sectional slenderness values. The current Australian/New Zealand, North American, and European design guidelines for stainless steel were assessed using the available experimental and numerical data. It is demonstrated that the current design standards fail to appropriately account for the local overall interaction effect in stainless steel I-columns.

Inelastic Plate Buckling

Current models to determine the local buckling stress of inelastic plates under in-plane loading are based on plastic deformation theory and semirational or empirical relationships. A successful J2 flow theory describing inelastic local buckling of initially perfect plates needs to avoid two well-known pitfalls known as the “inelastic column buckling paradox” and the “plastic buckling paradox.” While the former problem, which found its origin in 1895 in Engesser’s double modulus approach, was resolved by Shanley in the late 1940s, a convincing solution of the plastic buckling paradox has not yet been presented. This paper proposes a modification to the J2 flow theory which hinges on the determination of the shear stiffness from second-order considerations. A differential equation is derived which describes the incremental plate deformations at the inelastic local buckling load. The differential equation is studied for two cases of boundary conditions: a plate simply supported along four edges and a plate ...

Sidewall Buckling of Equal-Width RHS Truss X-Joints

AbstractThis paper presents a new design methodology for equal-width rectangular hollow section (RHS) X-joints failing by sidewall buckling. In the new approach, a slenderness parameter is defined based on the elastic local buckling stress of the sidewall, idealized as an infinitely long plate under patch loading. A Rayleigh-Ritz approximation is thereby used to obtain a closed-form solution. The proposed design equation is verified against experimental results over a wide range of wall slenderness values obtained from the literature and complemented by a brief experimental program carried out by the authors. It is demonstrated that the new design equation yields excellent results against the experimental data. Finally, a reliability analysis is performed within the framework of both the Eurocode and the AISI standards to ensure that the proposed design equation possesses the required level of safety. The newly proposed equation strongly outperforms the current Comite International pour le Developpement e...

Notched Strip Tensile Tests to Determine Yield Characteristics of Stainless Steel

AbstractThis paper investigates the use of notched strip tensile tests, previously proposed, to determine the yield characteristics of stainless steel. The original concept is thereby improved in two important ways. First, digital image correlation techniques are used to allow an accurate measurement of strain rates in a very localized area. Second, new theoretical developments are presented that eliminate the need for measuring the applied load and allow the yield surface of an anisotropic material to be determined starting from a parameterized equation. An experimental program is described where the method has been successfully applied to a ferritic grade as well as an austenitic grade stainless steel. As a disadvantage, a relatively large scatter in test results appears to be intrinsic to the method of notched strip tests.