Steel orthotropic decks provide a lightweight form of construction, essential for weight-critical structures. However, their cost and poor record of fatigue durability has discouraged their use for mainstream construction. As a result, steel decks are generally considered an option of last resort, only used where the minimisation of self-weight is essential, such as long-span and moveable bridges. An innovation is proposed to overcome these problems and transform the design of steel decks. The innovation is based upon the use of laser welding to produce an enclosed ‘sandwich panel’ profile. The sandwich profile shown below overcomes many of the constraints to structural performance associated with the use of conventional orthotropic steel decks. S. R. Bright, PhD, BEng, CEng, MICE Cass Hayward LLP, York House, Welsh Street, Chepstow J. W. Smith†, BSc (Hons), PhD, CEng, FIStructE, FICE (†Deceased) Dept. Civil Engineering, University of Bristol, Bristol
By pre-stressing a newly developed steel deck, prior to delivery to site, clear composite floor spans in excess of 11m can be readily achieved without the need for temporary propping. A prototype of the composite floor has been successfully tested and the results presented previously. This paper explains the basic engineering mechanics of the new system together with design equations. The three basic stages of pre-stressing the steel deck, pouring the wet concrete during the construction stage, to bring about reactive post-stress action, and the behaviour of the final composite section are explained. The design equations are compared against the test results from the prototype showing that the floor’s behaviour can be adequately predicted. The advantages and disadvantages of the new floor system are also discussed. F. R. Miller, BSc(Hons), CEng, MIStructE Offshield Ltd, Wilmslow, Cheshire Prof. C. G. Bailey, BEng, PhD, CEng, FICE, MIStructE, MIFireE School of Mechanical, Aerospace and Civil Engineering, The University of Manchester