Extension of Funchal Airport
Eng. António Segadães Tavares
The choice of the “Secil Civil Engineering Prize 2001” jury fell on the Structure for the Runway Extension at Funchal Airport, designed by Engineer António Segadães Tavares. This was chosen from a selection of projects of considerable merit nominated by the Jury, which was chaired by Engineer António Reis.
In the words of the Chairman, “The uniqueness of the design for the Runway Extension at Funchal Airport, played undoubtedly a major role in the jury’s final decision. It involved, on the one hand, a work whose design was developed in particularly complex conditions. The implementation during the works of the solutions studied required a high technical capacity for solving specific problems on the part of the designer and the other parties involved.”
António Segadães Tavares was born in 1944 in Luau, Angola. He studied at the Faculty of Engineering at the University of Porto, from where he graduated in 1968 with a Degree in Civil Engineering, with an average final mark of 16/20. He was awarded the Engineer António de Almeida Foundation Award for the best student of his course. He also received the Leca Construction Award in 1998 and he holds the honour of Grand Officer (GOC) of the “Order of Merit”.
He has worked as a designer since 1969, and has participated in numerous works, individually or in collaboration, whose main emphasis has been on the areas of structures and foundations, as well as project coordination and review. He began his professional career in the National Laboratory for Civil Engineering, and was then Head of the Department of Studies and Projects for the constructor Teixeira Duarte, and Technical Director of TRIEDE, and he is now Senior Partner and Director of STA – Segadães Tavares & Associados, Engenheiros e Arquitetos Consultores, Lda.
He has taught at the Instituto Superior Técnico, the Faculty of Engineering of the University of Luanda and the National Laboratory for Civil Engineering. He is currently Associate Professor at the Department of Civil Engineering, Faculty of Science and Technology, Nova University of Lisbon.
Antonio Tavares Segadães is the author of “Análise Matricial de Estruturas”, published in 1972 by the National Laboratory for Civil Engineering, and has had several papers published in professional journals and presented at national and international conferences.
He is a Senior Member of the Engineers’ Association, specialising in structures, and is a member of the International Concrete Federation, the American Concrete Institute, the International Society for Soil Mechanics and Foundation Engineering and the Portuguese Geotechnics Society.
He has worked as a consultant in various countries, including: Angola, United States of America and Venezuela, particularly in the area of Special Structures Design.
Of his recent projects in the field of special structures, the Runway Extension at Funchal Airport, the roof over the Ceremonial Square adjacent to the Portugal Pavilion in the grounds of Expo`98, and the Reinforcement and Consolidation of the Rossio Railway Tunnel and Emergency Galleries project are particularly notable.
In the area of services buildings, highlights include works such as the Centro Cultural de Belém, and the Portugal Pavilion, the Ceremonial Square and the Camões Theatre for Expo 98; many commercial buildings like “Vasco da Gama Shopping”, “Algarve Shopping” and the Grandella Building; and also the Vilamoura Marina Hotel and the Meridien Hotel. He has also worked on buildings for higher education, examples of which are the Drama and Film School in Amadora; the Faculty of Veterinary Medicine in Lisbon; the Agrarian School Complex in Santarém and the Air Force Academy in Sintra.
Finally, in the field of refurbishment of Ancient Buildings, a number of works stand out in the Reconstruction of the Affected Area of Chiado, the Bank of Portugal building in Évora; the Headquarters of Montepio Geral in Lisbon and his participation in the adaptation to a Pousada of the Flor da Rosa Monastery in Crato.
In 1993 ANAM, Aeroportos e Navegação Aérea da Madeira, S.A. issued a tender for the Madeira Airport Extension contract, located in Santa Catarina, about 20km from the city of Funchal.
The international tender for the contract was based on studies conducted by HIDROSERVICE (Brazil) and by Eng. Edgar Cardoso, whose specifications were restricted to the submission of variants and new solutions.
At the invitation of what would be NOVAPISTA, an enterprise group formed by Zagope, S.A. and OPCA, S.A. (Portuguese companies), Spie Batignolles, S.A. (a French company) and Andrade Gutierrez (a Brazilian company), Eng. António Segadães Tavares put together a technical team to study constructive solutions and possible variants.
The studies, that were initially limited by nature to the most appropriate technical and economic solutions for making the foundations of the structure, came to be extended to the entire structure, while STA undertook the development of the foundations and structure design for the expansion of Funchal Airport, the first phase of which was the extension of the runway to 2336 metres (corresponding to a structural intervention of 550 metres) followed by a second phase of expansion (corresponding to an intervention of 660 metres), extending the runway to a final length of 2781 metres.
In order to provide the Runway with the characteristics that would enable larger in-service commercial aircraft to operate there, it was decided to make the extension via a bridge designed to support an unusual load – the landing of an aircraft of the “Boeing 747-400” type.
The construction of the extension was divided into two phases for budgetary and funding reasons:
- The first phase, beginning with a head wall which limited the former runway to the north-east, separating it by a structural expansion joint, was done using a 546 metre long bridge.
- The second phase, similar to the first and also separated by an expansion joint, extended to the cliffs that limit the reclaimed bay to the north, and had a maximum length of 462 metres.
Description of Works
The structural solution adopted consisted of a set of porticos, oriented transversely to the axis of the runway and 32 metres apart from each other. The cross-members of the porticos (cross girders) supported a slab in pre-stressed concrete 189 metres wide. The thickness of the slab varied between 1 metre at a central strip of 12m and 1.7m by the porticos, the transition being made by circular curves with a constant radius.
Each of the transverse porticos generally consisted of six pillars spaced at 32 metres, which supported the cross girders, with cantilevered beams at each end with a span of 14.5 metres.
The height of the cross girders, in pre-stressed reinforced concrete, ranged from 3.6m (at mid-span) and 5.6 metres at the pillar supporting point.
The pillars had a circular section 3 metres in diameter and heights up to 50 metres in the area reclaimed from the sea, which decreased as the structure approached and straddled the cliffs.
The expansion joints separating the first and second phases, allowed both parts to act independently, in particular in response to temperature variations, shrinkage and creep of the structural materials. Similarly, the joints isolated the structures of the extension of the shore structures, ensuring an independent seismic response in both types of structure.
The troubled genesis of the volcanic soil of the Island of Madeira determines its characteristics, with significant variations over short distances (more or less compact basalt shifting to vacuolar and slaggy basalts, volcanic ash and tuffs, clastolavas, scree deposits, gravel pits with blocks reaching dimensions of 2 cubic metres). Furthermore, the frequent occurrence of hollows, grottoes and caves required a constant, meticulous geotechnical survey work.
According to the nature of the foundation soil, foundations were shallow shoe foundations or piled foundations in reinforced concrete moulded “in-situ” or metal.
When highly compact soils were of lesser depth, the solution adopted was to make shoes, in a cylindrical shape, of 8 metres diameter and 2.2 metres high at the top, and octagonal, 2.5 metres high at the bottom.
In areas where the ground had poor characteristics, the typical solution was to make groups of 8 piles with a diameter of 1.5 metres, with the tip of the piles reaching depths of 60 metres.
In addition to the loads corresponding to the specific weights of the structural members and all other fixed members, such as wheel guards and safety barriers (permanent loads) and the weights of the runway surface materials, aircraft overloads were of particular relevance.
This typical aircraft overload imposed for the structural design corresponded to the maximum weight of a BOEING 747-400, i.e. 3960 kN (approximately 400 tonnes), with a landing gear consisting of 4 four-wheel bogies.
Seismic action, wind action, concrete retraction and creep actions and the actions resulting from even and differential temperature variations were also considered.
Some of quantities involved in the extension of the runway were:
- Excavations – 3,500,000 cubic metres
- Landfills – 3,400,000 cubic metres
- Piles – (1500mm diameter) 23,000 metres
- Piles – (1200mm diameter) 3,000 metres
- Structural Concrete – (C30/35) 340,000 cubic metres
- Rebar steel – (fsy = 400 Mpa) 32,000 tonnes
- Pre-stressing steel – (tonnes) 16,000 tonnes
- Pre-stressing steel – (forces) 850,000,000 kN/m
Work Technical Datasheet: Extension Structure of Funchal Airport
Location: Santa Catarina, Autonomous Region of Madeira
Design: Eng. António Segadães Tavares
Client: ANAM – Aeroportos e Navegação da Madeira, SA
Structure: STA , Segadães Tavares e Associados
Contractor: Novapista ACE