Guidance Note. The Woolf Reforms and Civil Procedures Rules

Structural engineers have always been fascinated with building the biggest and best of structures. The efects of scaling-up the size of structures is explored, with particular reference to failure by fracture and fatigue. It is concluded that size does matter for structural engineers. Professor F.M. Burdekin

Cowboy builders: who controls their work? Stan Lawrence (by now well known to readers) writes: NCE (2 September) highlights the scenario of the consequence of the recent Ashford collapse, where four site workmen were killed when a three-storey office block collapsed because of substandard construction a decade or more ago.

‘Stressed skin ’design has generally been applied primarily to roofs or walls with a single skin of sheeting directly fixed to the purlins, side-rails or beams by, for example, self-drilling, self-tapping screws or fired pins. However, many modern roof systems involve two metal skins with insulation positioned between them, and this affects their in-plane resistance. This paper reviews the potential for the stressed skin design of these modern roofs on the basis of eight full-scale diaphragm tests of diflerent, but ‘generic’, roof systems. The tests showed that built-up roofs comprising a liner tray, Z spacers, and roof sheeting , performed well and that significant ‘composite’ action between the roof sheeting and the liner tray took place. The performance of all liner trays could be enhanced significantly if their local shear buckling resistance is improved, leading to enhanced potential for use in ‘stressed skin’ design. Professor J.M. Davies and R.M. Lawson