Flexural behaviour of hot-finished high strength steel square and rectangular hollow sections

High strength steels, considered in the context of the structural Eurocodes, as steels with a yield strength over 460 MPa, are gaining increasing attention from structural engineers and researchers owing to their potential to enable lighter and more economic structures. This paper focuses on the bending strength of hot-finished high strength steel (HSS) square and rectangular hollow sections; the results of detailed experimental and numerical studies are presented and structural design rules for HSS cross-sections are proposed. A total of 22 in-plane bending tests, in three-point bending and four-point bending configurations, on HSS sections in grades S460 and S690 were conducted. The experimental results were replicated by means of non-linear finite element modelling. Upon validation of the finite element models, parametric studies were performed to assess the structural response of HSS sections over a wider range of cross-section slenderness, cross-section aspect ratio and moment gradient. The experimental results combined with the obtained numerical results were used to assess the suitability of the current European (EN 1993-1-1 and EN 1993-1-12) cross-section classification limits for HSS structural components. The reliability of the proposed cross-section classification limits was verified by means of the EN 1990 - Annex D method.The Research Fund for Coal and Steel (RFCS) under grant agreement No. RFSR CT 2012-00028. V&M DEUTSCHLAND GMBH, Mr. Gordon Herbert, Mr. Fillip Kirazov and Mr. Isaak Vryzidi

Approximations in alternate load path capacity of welded unreinforced flange-bolted web connections

In the event of sudden column removal, beam-to-column connections play a significant role in transferring the load carried by the damaged parts to the intact ones. This role involves experiencing a magnified bending moment and axial load which ultimately produces catenary action in the beam. This mechanism can eventually replace the flexural action in carrying the gravitational loading. Therefore, the beam and the connection must be able to develop and maintain a sufficiently large axial tension which explains the important role that connections play in mitigating progressive collapse. However, the strength and ductility of the out-of-plane members and connections affect the total load carrying capacity of structures employing moment connections. In this study, using component-based modelling, the effect of modelling these structural elements in the final result is investigated. Analysis results of a generic structure revealed that ignoring the out-of-plane members and connection can lead to overestimate the load carrying capacity of the affected span by 72%