P. M. M. Vila Real

A new proposal of a simple model for the lateral-torsional buckling of unrestrained steel I- beams in case of fire: experimental and numerical validation

Abstract The behaviour of Steel I-Beams exhibiting lateral-torsional buckling at elevated temperature has been studied by means of experimental and numerical analysis. The authors in an earlier paper have presented an analytical formula for the buckling resistance moment in the fire design situation. This new proposal, different from the actual proposal of the Eurocode 3 Part 1.2 has been validated in this work by comparison with the results from a set of 120 experimental and numerical tests performed on IPE 100 beams, submitted to temperatures varying from room temperature to 600 °C. The numerical simulations have been based on the measured geometrical dimensions of the cross-sections, the longitudinal imperfections, i. e. the out of straightness of the beams, the residual stresses and the yield strength. The Eurocode simple model promotes ultimate loads that depend mainly on the non-dimensional slenderness of the beams. The analytical results provided by the Eurocode 3, for a certain range of the slenderness, appear to be unsafe when compared with the numerical and experimental results. It is shown that the new proposal is safer than the Eurocode 3 formulas.

Displacement Field and Strain Distribution in a Rotating Annular Disk

Abstract The displacement field and strain distribution in a thin rotating disk with constant thickness and density are found based on Mises’ yield criterion and its associated flow rule. The material of the disk is elastic-perfectly plastic and the assumption of plane stress is adopted. The solution is illustrated by an example.

Elastic-plastic stress distributions and limit angular velocities in rotating hyperbolic annular discs:

Abstract Plastic analytical stress analysis of a rotating annular disc with its contours being free from the radial pressure and with specifically variable thickness is presented in terms of the Mises-yield criterion and its associated flow rule. The hyperbolic form of thickness variation is considered and optimized towards the maximum rotational speed and favourable stress combinations. Radial and circumferential stress distributions in the disc both in the intermediate elastic-plastic and in the limit plastic states are obtained. As a particular case, limit elastic angular velocity parameter is derived. The influences of rotational speed as well as the discs thickness profile on the plastic solution and size of elastic-plastic zone are demonstrated and discussed. The results obtained may be used for the correct implementation of numerical codes and preliminary engineering design.

Numerical Modelling of the Lateral-Torsional Buckling of Stainless Steel I-Beams: Comparison with Eurocode 3

This work presents a numerical study of the behaviour of stainless steel I-beams subjected to lateral torsional buckling and compares the obtained results with the beam design curves of Eurocode 3. The EN version of part 1-1 of Eurocode 3 [1] introduces significant changes in the evaluation of the lateral torsional buckling resistance of unrestrained beams, that improves the too conservative approach of 1992 version [2] of Eurocode 3 in case of non-uniform bending through the introduction of a correction factor. In fact there is an additional beneficial effect resulting from reduced plastic zones connected with the variable bending diagram along the member that was not considered in the earlier versions of the Eurocode 3. This beneficial effect (see Figure) still remains to be taken into account in Part 1.4 of Eurocode 3 -’ supplementary rules for stainless steels’ [3]. The present study aims at evaluating the influence of the loading type on the lateral-torsional buckling resistance of stainless steel I-beams and investigates the need of using a similar correction factor as the one used for carbon steel.

Deformation and Stress Analysis of an Anisotropic Rotating Annular Disk

The plane state of stress in a rotating elastic-perfectly plastic anisotropic annular disk of constant thickness and density is studied. It is shown that the key design geometric parameters of the disk, namely, its mean radius and width, influence the stress and strain distributions. To explicitly get the total strain field, including elastic and plastic regions, a new, original, semi-analytical method is developed. The disk material is assumed to be elastically and plastically anisotropic, obeying the Hills quadratic yield criterion in the plastic zone and the generalized Hookes law in the elastic zone. The results may be used in a preliminary design of rotating disks as well as in implementation of numerical codes.

Numerical Validation of the Eurocode 3 Design Rules for Lateral-Torsional Buckling of I-Beams

This work presents a numerical study of the behaviour of steel I-beams subjected to lateral torsional buckling. The results obtained are compared with the beam stability design curves from Eurocode 3.

Statistical Evaluation of the Eurocode 3 Design Rules for Lateral-Torsional Buckling of I-Beams

This work reports the statistical evaluation of resistance design models for lateral-torsional buckling of I-beams according to the EN1993(eurocode 3) [3] and EN1990(eurocode 0) [2].

Lateral-torsional Buckling of Ferritic Stainless Steel Beams in Case of Fire

This work presents a numerical study of the behaviour of ferritic stainless steel I-beams subjected to lateral-torsional buckling and compares the obtained results with the beam design curves of Eurocode 3. New formulae, for the lateral-torsional buckling, that approximate better the real behaviour of ferritic stainless steel structural elements in case of fire are proposed. These new formulae were based on numerical simulations using the program SAFIR, which was modified to take into account the material properties of the stainless steel.