New Extensions of the Loht Steel Works, at Lohr am Main

Abstract

The geometrical properties of the hyperbolic paraboloid provided certain advantages to the architects, when they designed the new casting mill of the Lohr steel works, especially in regard to illumination and ventilation. Two similar hyperbolic parabolic surfaces, bounded by three straight and two curved edges, and joined together by a transition surface, form the top part of the ventilation dome. The northern elevation constitutes a skylight, of trapeze-like shape. Each of these domes, whose plan dimensions are 13.5 by 15 ms, rest on isolated supports, which, in turn, along the longitudinal direction of the nave, serve to support a bridge crane, with a 13.5 m span. The lower part of the nave has a height of 7.50 m, up to the springers of the roofing shell. The total height to the top of the dome is 16.3 m, so that the shell roof has a rise of 8.8 m. The statical behaviour of the roof was investigated on a reduced 1:10 scale model. As there is always excess heat inside the nave, there has been no need for thermal insulation. Advantage has also been taken of the high degree of waterproofness of high quality concrete, in order to avoid the need of applying any external waterproofing treatment. This project can be regarded as a significant contribution to current progress in shell roof construction.