Restrained behaviour of beams in steel frames exposed to fire
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
The current design procedures prescribed by the codes for design of steel beams at elevated temperatures require that the ultimate flexural resistance of the beam should be checked against the applied loading. This approach does not take into account the redistribution of bending moment due to fire exposure that takes place in a redundant frame. The axial and rotational restraints at the beam to column connections in such a frame play an important role as to how the beam behaves in restrained conditions when exposed to fire. This is particularly important at relatively high temperatures when the beam has undergone significant deflections and as the catenary action in the beam gradually takes over as the resisting mechanism beyond the limiting temperature prescribed by the codes.Simplified design procedures that satisfactorily describe the restrained beam behaviour should be used to avoid the high cost and complexity of finite element analysis and fire tests. A proposed simplified design procedure has been used to analyse axially and rotationally restrained beams in sub-frames in this study and the results are compared to the results from their finite element models. The finite element models of the sub-frames were validated against fire tests conducted on sub-frames. The proposed method was shown to have satisfactorily predicted the restrained beam behaviour under different load levels and temperature distributions.The validated finite element models were also used to investigate the effect of changing different parameters of the sub-frame, such as temperature distribution, boundary conditions and fire protection on the connection region. The distribution of strains in the connection components were shown to have been significantly affected by changing these parameters.
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2013. , 191 p.
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Research subject Steel Structures
IdentifiersURN: urn:nbn:se:ltu:diva-18393Local ID: 869cfc73-3514-416a-a0d3-bbb119fa95caISBN: 978-91-7439-630-0 (print)ISBN: 978-91-7439-631-7 (electronic)OAI: oai:DiVA.org:ltu-18393DiVA: diva2:991401
Godkänd; 2013; 20130506 (andbra); Tillkännagivande licentiatseminarium 2013-05-16 Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Naveed Iqbal Ämne: Stålbyggnad/Steel Structures Uppsats: Restrained Behaviour of Beams in a Steel Frame Exposed to Fire Examinator: Professor Milan Veljkovic, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Assistant Professor Aldina Santiago, University of Coimbra, Portugal Tid: Tisdag den 4 juni 2013 kl 09.00 Plats: F1031, Luleå tekniska universitet2016-09-292016-09-29Bibliographically approved