Lateral instability of elliptical hollow section beams

Law, K. H.; Gardner, Leroy

doi:10.1016/j.engstruct.2011.12.008

Cited by 48 publications

(38 citation statements)

References 24 publications

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“…In solid-beam lattices, the nodes form solid joints that hinder beam rotation, shortening the effective length of the constituent beams and generally leading to higher stiffnesses. While beam models that capture shearing behavior, such as Timoshenko models, can be used to more accurately capture the behavior of short beams [20,46], they lead to a drop in the effective stiffness, which is opposite from the trend observed here. Accurately replicating the mechanics of solid lattices with computationally efficient models, similar to what is done using beam elements, requires in-depth investigations into the role of nodes on the mechanical properties, which is outside the scope of this work.…”

Section: A C C E P T E D Accepted Manuscriptcontrasting

confidence: 50%

Reexamining the mechanical property space of three-dimensional lattice architectures

et al. 2017

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Lightweight materials that are simultaneously strong and stiff are desirable for a range of applications from transportation to energy storage to defense. Micro-and nanolattices represent some of the lightest fabricated materials to date, but studies of their mechanical properties have produced inconsistent results that are not well captured by existing lattice models. We performed systematic nanomechanical experiments on four distinct geometries of solid polymer and hollow ceramic (Al 2 O 3 ) nanolattices. All samples tested had a nearly identical scaling of strength (ߪ ௬ ) and Young's modulus ‫)ܧ(‬ with relative density (ߩ̅ ), ranging from ߪ ௬ ∝ ߩ̅ ଵ.ସହ to ߩ̅ ଵ.ଽଶ and ‫ܧ‬ ∝ ߩ̅ ଵ.ସଵ to ߩ̅ ଵ.଼ଷ , revealing that changing topology alone does not necessarily have a significant impact on nanolattice mechanical properties. Finite element analysis was performed on solid and hollow lattices with structural parameters beyond those realized experimentally, enabling the identification of transition regimes where solid-beam lattices diverge from existing analytical theories and revealing the complex parameter space of hollow-beam lattices. We propose a simplified analytical model for solid-beam lattices that provides insight into the mechanisms behind their observed stiffness, and we investigate different hollow-beam lattice parameters that give rise to their aberrant properties. These experimental, computational and theoretical results uncover how architecture can be used to access unique lattice mechanical property spaces while demonstrating the practical limits of existing beam-based models in characterizing their behavior.

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Section: A C C E P T E D Accepted Manuscriptcontrasting

confidence: 50%

Reexamining the mechanical property space of three-dimensional lattice architectures

et al. 2017

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“…Nowadays these values are still considered acceptable (Grilo, 2015). Recently, Law and Gardner (2012) obtained the residual stresses in a similar profile, with elliptical cross section, and concluded that these stresses correspond to 10 to 15% of the steel yielding resistance, confirming the previous conclusions about the circular hollow sections. The initial geometric imperfection, or initial crookedness, of steel members is inherent to the fabrication process and can be amplified during transportation and assembly of the structure.…”

Section: Residual Stresses and Geometric Imperfectionssupporting

confidence: 69%

Behavior and design of built-up compressed steel members composed of concentric hot rolled circular hollow sections

Grilo

Fakury

Silva

et al. 2018

Lat. Am. j. solids struct.

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This research presents a study of the behavior of built-up compressed steel members composed of concentric hot rolled circular hollow sections. The use of these members is an innovative solution of practical interest for situations in which a single member does not reach the required compressive strength. Some technically and economically viable design and fabrication solutions to built-up members composed of concentric hot rolled circular hollow sections are presented. For the validation of numerical results, models of singular hollow sections are made and compared to the EN 1993-1-1, and the results obtained with numerical models were satisfactory. The compression resistance of these numerical models differs less than 9% from the EN 1993-1-1 values. Once the numerical modeling was validated, the study of built-up members was made, considering the tubes always united at the extremities by end plates, and along the length by fixed interconnections or sliding interconnections or, furthermore, without interconnections. For these three different conditions, several numerical models using FEM via Abaqus software were simulated to obtain and compare the compression resistance. The results show that these built-up sections with fixed and sliding interconnections have very similar behavior to the results obtained with European Standard procedure, when considering equivalent areas and inertias for the built-up section. Also, it shows that this observation does not apply to the sections without interconnections. Comparative graphs of compression resistance curves were generated, as also some graphs that show the distribution of the compressive force between each member of the built-up section. Finally, a formulation for the design of built-up sections without interconnections along the tubes was proposed to avoid robust computational methods.

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“…Measurements of the cross-section geometry, member length L (measured between the pinned ends) and maximum global geometric imperfections in the major g,y and minor axes g,z (determined by means of a laser beam directed along the member length) were taken prior to testing and are reported in Table 2. Residual stresses were not measured in this study, but were found to be of very low magnitude in similar specimens examined previously (Law and Gardner, 2012).…”

Section: Experimental Set-upmentioning

confidence: 91%

“…For EHS member instability, experimental and numerical studies have been conducted on column buckling (Chan and Gardner, 2009;Scullion et al, 2011;Espinos et al, 2011;Young and Jhu, 2012), lateral torsional instability (Law and Gardner, 2012) and beamcolumn behaviour under combined compression plus uniaxial bending (Law and Gardner, 2013). However, no studies of the global instability of EHS beam-columns under combined compression plus biaxial bending have been performed, and this is the topic of the present paper.…”

Section: Introductionmentioning

confidence: 99%

“…Initially, the behaviour of the tested biaxially loaded beam-columns was replicated using the measured dimensions of the test specimens and measured material stress-strain data. Four-noded, reduced integration shell elements with six degrees of freedom per node, designated as S4R in the ABAQUS (2010) element library, were chosen for the FE models since they were employed successfully in the previous simulations of hot-finished EHS (Chan and Gardner, 2008a;Chan and Gardner, 2009;Law and Gardner, 2012). A mesh convergence study was undertaken and the uniform mesh density of 15 × 15 mm was found to be suitable, which is able to achieve accurate results with reasonable computational effort.…”

Section: Numerical Simulationsmentioning

confidence: 99%

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Global instability of elliptical hollow section beam-columns under compression and biaxial bending

Law

Gardner

2013

Int J Steel Struct

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The global instability of elliptical hollow section members under combined compression plus biaxial bending is studied in this paper by means of laboratory testing and numerical simulations. A total of 9 beam-column tests were carried out under different combinations of compression and bending about both principal axes. The material properties of the tested sections were determined by means of tensile coupon tests. All tested elliptical hollow sections were EHS 150755, and three nominal member lengths of 1 m, 2 m and 3 m were considered. Graphs of applied load versus mid-span bending moment, based on theoretical first and second order elastic considerations and the experimental second order inelastic response, are presented and described. Numerical models were initially validated against the experimental data using measured material and geometric properties, including imperfections. The models were subsequently employed in parametric studies to assess the influence of member slenderness and cross-sectional aspect ratio on the structural response. Finally, based on the experimental and numerical findings, design rules for hot-finished EHS beamcolumns were assessed and statistically verified.

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Lateral instability of elliptical hollow section beams

Cited by 48 publications

References 24 publications

Reexamining the mechanical property space of three-dimensional lattice architectures

Reexamining the mechanical property space of three-dimensional lattice architectures

Behavior and design of built-up compressed steel members composed of concentric hot rolled circular hollow sections

Global instability of elliptical hollow section beam-columns under compression and biaxial bending

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