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The Structural Engineer
The Structural Engineer

BS 5950-1:2000 introduced major changes to column design, particularly in sway frames. Some of the new clauses are badly draughted and contain anomalies. The new requirements for columns in sway frames make design more complicated and also more conservative. However analysis of the stability of columns in sway frames demonstrates that the second order analysis and notional lateral forces now required for load Combination 1 are unnecessary, as adequate allowances for buckling and initial imperfections are already included in standard column design stresses. Revisions to rectify these problems are proposed. Alasdair N. Beal, BSc, CEng, MICE, FIStructE Thomasons LLP

The Structural Engineer
The Structural Engineer

This paper presents the results from the testing of a prototype for a new long-span composite floor system known as Tekdek. The tested prototype achieved a clear unpropped span of 10.5m, which is significantly greater than any other comparable composite system currently on the market. The system introduces a new concept of prestressing the steel deck prior to pouring the concrete. The prototype deck was tested to investigate its ultimate compressive prestressing capacity and its performance under pouring of the concrete to form the completed composite system. In addition, the constructed composite floor system was tested under vibration, cyclic and ultimate load. The performance when pouring the concrete, and the tests on the composite system, were repeated for two different decks (designated A and B) which were subjected to different prestressing loads. It was found that the composite system, based on a one unit width, had a fundamental frequency between 4.4 and 4.5Hz and achieved a maximum load carrying capacity between 9.0 and 9.87kN/m2, which is acceptable for most buildings. An indicative fire test provided the temperature distribution through the cross-section, when subjected to the standard fire curve, allowing the fire resistance of the system to be estimated. C. G. Bailey, BEng, PhD, CEng, FICE, MIStructE, MIFireE School of Mechanical, Aerospace and Civil Engineering, The University of Manchester P. M. Currie, BEng, PhD School of Mechanical, Aerospace and Civil Engineering, The University of Manchester F. R. Miller, BEng, CEng, MIStructE Offshield Ltd, Wilmslow, Cheshire

The Structural Engineer

Light steel construction is often designed to maximise the benefits of interactions with other materials and this paper reviews examples of composite applications of light steel components in flooring and roofing. New forms of steel-timber composite ‘plyweb’ floor joists and ‘open’ roofing systems, and steel-gypsum composite floor joists are investigated. Design recommendations are presented for lightweight floors, as influenced by interactions with boards, which include both static and dynamic criteria. R. M. Lawson, BSc(Eng), PhD, CEng, MICE, MIStructE, MASCE, ACGI SCI Professor, University of Surrey R. Pedreschi, BSc(Eng), PhD, CEng, MICE Professor of Architecture, University of Edinburgh R. G. Ogden, BA(Arch), PhD SCI Professor of Architecture, Oxford Brookes University P. J. Grubb, BSc(Hons), CEng, MICE Consultant to The Steel Construction Institute

The Structural Engineer
The Structural Engineer

This paper is the result of an IStructE Educational Trust Rowen Travel Award which enabled the author to undertaken the research project. Applicants define their own research topic, the objectives and itinerary of people and places to visit. The author travelled to Japan, Australia and America to investigate the worldwide uses of high-strength steel. This paper is a brief summary of the dissertation resulting from 4 weeks of research.

The Structural Engineer
The Structural Engineer
The Structural Engineer
The Structural Engineer