Resumen
Many alternative structural systems have recently been proposed in South Africa in an attempt to reduce costs of lightweight steel structures. Most of these comprise premanufactured components which are bolted together on site. Large industrial type structures are usually constructed with hot-rolled steel profiles, so that, apart from the architect, a structural engineer, manufacturer and contractor would be required. As an alternative to these existing practices, this article proposes design and construction techniques that may reduce the cost of the structure and at the same time create employment for emerging contractors. The proposed construction method consists of the welding together of lightweight profiles on site. For the structure the following is proposed: short pile footings to provide partial fixidity to the structure, effective and lightweight compositions of cold-formed thin-walled profiles for structural elements, and stressed skin diaphragm design wherein the cladding, purlins and structural elements work together as one unit. Alternative portal frame configurations were analysed and designed to form larger structures, which indicates the versatility of the proposed construction concept. The article further illustrates that the utilization of the proposed construction method results in more economical structures and discusses applications of the principles on a number of real structures.