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Engineers unfortunate enough to have much contact with lawyers over the last few months may have heard those lawyers uttering a strange incantation: ‘D &F Estates’. To have a case ‘D & F-ed’ is not an ancient lawyers’ curse; it means that a claim which, 3 or 4 years ago, might have had a respectable chance of success has now been blown out of the water by the House of Lords’ decision in a case called D & F Estates v. the Church Commissioners and Others. The title of the case (like much of the decision itself) is rather confusing because the ‘real’ defendant was Wates, the building company. D & F Estates owned a flat in a 1960s block developed by the Church Commissioners, and built by Wates. Wates had employed a domestic subcontractor to plaster the flat. The plastering had not been done correctly, and about 15 years after the flat was completed, the old plaster had to be hacked off and replaced. D & F Estates had bought the flat from the Church Commissioners, but did not pursue any claim against the Church Commissioners, probably because it would have been statute barred. They therefore sued Wates in negligence (having no contract with them), claiming that Wates was responsible for the acts and defaults of its own domestic subcontractor. The claim failed, on the basis that the domestic subcontractor was an independent contractor, and in an action in negligence Wates could not be held responsible for the acts and defaults of an independent contractor. At the time of the decision, it was greeted with some surprise, particularly by architects, who could not understand how a main contractor could be released from responsibility for the acts and defaults of a domestic subcontractor. From a lawyer’s point of view, however, the remarkable thing about the decision was that the House of Lords went out of its way to restate and emphasise the differences between actions based on contracts and actions based on negligence, the lines between those two types of actions having become considerably blurred over the last 15 years. J.J. Ward
A description is given of experimental tests on 15 steel panels, each fabricated by spot welding steel face plates onto a corrugated steel core to form a sandwich. This form of construction is being investigated with a view to its use as decking on offshore platforms. All the panels had plan dimensions of 2.1 m x l m and cores consisting of top-hat stiffeners (Fig 1) of depth 60 mm, placed side by side. Each panel was tested by subjection to uniform lateral (z-direction, Fig l) loading over its entire surface, firstly when simply supported along all boundaries and then when simply supported across its y-direction boundaries only. C. Norris, Professor P. Montague and K.H. Tan
The application of the ABAQUS finite element package to the analysis of a troughed-core steel sandwich panel (Fig 2) is described, and the results are compared with those of closed solutions and experimental testing. Panels of this kind, which promise good strength-to-weight and strength-to-stiffness ratios, are of interest as lightweight decking for offshore platforms. The panel had high bending and shear stiffnesses in the x-direction (Fig l), i.e. the direction of the core troughs, and low bending and shear stiffnesses in the y-direction. It had a length-to-breadth ratio of 3 and a span-to-depth ratio of about 56, with a self-weight of 62 kg/m2. Subjected to a uniformly distributed z-direction load of 10 kN/m2 over its entire surface, it experienced an experimental central deflection of span/l33 when simply supported across its y-direction edges only and of span/428 when simply supported along all four edges. K.H. Tan, Professor P. Montague and C. Norris