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The Structural Engineer, Volume 69, Issue 2, 1991
Fabric laps Mr J. K. Botterill of Chessington has some queries about the lapping requirements for fabric in the concrete Codes, which he sees as giving quite inadequate guidance. Would any of our readers feel emboldened to offer their own opinions as to what should be done, and whether what Mr Botterill suggests can be justified? Verulam
Bernard Wex was one of those who came into engineering after serving in the armed forces during World War II. He wanted to become a pilot, but a minor eye defect precluded him from acceptance by the RAF and he joined the army in 1942. After Sandhurst he was commissioned in 1943 and spent the next 4 years as a tank commander with the 23rd Hussars. M.F. Parsons
Dr. P. A. Jackson (M) (Gifford & Partners) I have long thought it odd that the conventional design methods for ground supported slabs (including concrete paving slabs) and for suspended slabs are so fundamentally different. The latter are designed on the assumption that they are cracked and that the tensile strength of concrete contributes little to their behaviour and nothing to their flexural strength; the former are designed on the assumption that they are not cracked and that they work by the tensile strength of concrete. This difference would be logical if the stresses in ground supported slabs were lower than in suspended slabs and this often, although not always, appears to be the case if one considers only load-induced flexural stresses. However, cracks can also be induced by stresses from other effects such as shrinkage and temperature and, because of differences in the restraint, these stresses are often higher in ground supported slabs.