Implications of Eurocode for steel portal frames in Sri Lanka

Abstract

Portal frame structures are widely used all over the world and in Sri Lanka for warehouses and factory buildings as they allow a large column free area with a maximum open space. They are basically made out of steel. Speedy construction, flexibility in use and easy maintenance are the main advantages in steel portal frames. Up until now in Sri Lanka, steel portal frames were designed mainly according to the British standards. But Eurocode is a more updated set of guidelines formed through research and experience. This paper investigates the implications of Eurocode for steel portal frames in Sri Lanka. A field survey was carried out via questionnaires and responses in interviews to get a firsthand understanding of portal frame structures prevalent in Sri Lanka. With this experience, 48 different portal frames were selected for the parametric study to suit the Sri Lankan conditions varying the span range from 20m to 50m, eaves height from 4.5m to 6.0m and frame spacing from 4.5m to 9.0m. They were analysed to find the implications of Eurocode based on the methods proposed by the Steel Construction Institute. Results of parametric study were compared with each other and with available literature and publications. Identified implications are discussed in this paper concerning forces, moments and weight variations. A table was developed to obtain optimum column and rafter sections for selected ranges of parameters. No significant advantages were found in designing portal frames to elastic theory based on Eurocode compared to British standards in terms of weight. Main frame weight as a percentage of ULS axial force of a column (excluding the self weight of frame) was found to be in the range of 10% to 45% for 4.5m eaves height frames and 18% to 45% for 6.0m eaves height frames