Funchal Airport Extension, Madeira Island, Portugal

摘要

"Necessitas" (being necessary), Vitruvius wrote, is one of the characteristics that a construction must fulfil. The old runway of Madeira Airport, short by current standards, represented a serious restraint to the development needs of Madeira Island. The island is of volcanic origin. Mountains dominate its landscape, valleys are narrow and there are almost no plains. Studies carried out for several locations concluded that the site of the old Santa Catarina Airport was still the most suitable location for the new airport, which directed the decision of the extension of Funchal Airport runway for a bridge more than 1000 m long, 178 m wide and 57 m above a shallow-water bay; a bridge that was required to carry one unusual imposed load - a BOEING 747-400. The structural solution consists of 31 portal frames supporting the runway at spans of 32 m. The portal beams, 189 m long, support a 178 m wide prestressed concrete deck slab. The long length of the structure and the high prestress in the deck slab, contributed to the structure being very sensitive to long term effects such as creep and shrinkage. Considering this together with thermal effects, it was recommended that the structure be separated into two parts by expansion joints, allowing independent behaviour of both resultant structures.