Lateral torsional buckling in steel and composite beams

Present research project aims at improving and implementing the knowledge in the field of lateral torsional buckling (in short LTB) and at preparing design rules applicable to beam types, which are not satisfactorily covered in the existing standards Its issue is mostly practice oriented More especially, partially encased composite beams, steel castellated beams, web tapered I steel beams and erection phases of steel bridge girders of uniform section are especially of concern With a view to establish these rules, experiments are performed Their results are successfully compared with those of numerical simulations using finite element techniques. Appropriate FE softwares are then used to produce parametric studies, the latter aim at widening the ranges of variables, compared to those covered by the experiments The elastic LTB critical moment is a key step in the verification process Its expression becomes rapidly complex when the loading and support conditions differ from the standard ones and when the beam is fitted with discrete or continuous elastic restraints Dedicated softwares, which are made freely available, enable the designers to get rid of any analytical formulation The determination of the ultimate LTB moment resistance according to ENV1993-1-1 is revisited and improved Application of the design process is illustrated through several fully solved and documented worked examples Also recommendations are given on how to perform FE analyses of complex situations involving LTB The main outcome of the research project consists in the so-called Book 2 The latter consists mainly in a Design Guide, where all the practical issues relative to above items are gathered Above objectives were achieved through an international cooperation involving five main partners, some of them being assisted by third parties The respective activities of these partners, which are described in more details in Book 1, are briefly summarised below.