This project has revealed itself to be an enticing engineering work of structural rehabilitation. A part of the existing building was preserved under the scope of the architecture programme, being that the main goal was to have a rehabilitated/reconstructed building with the characteristics/specificities of the original materials. Reinforces have been ‘surgically” introduced thus giving the building an adequate behaviour in case of quakes, which was lacking in the original construction.
The licensing project, alterations, structures and foundations, on the two floors, located at 35 and 19, Rua do Facho in Óbidos, destined to local housing, was elaborated in alignment with the programme extricated from the architecture project and executed based on structural analysis, with simplified models built through the automatic calculation programme – which has already been utilised and tested. The adopted structure, harmonised with the architecture programme’s philosophy, was maintained within the essence of the structural system, namely within the outer walls.
The state of degradation of the remainder of the structure, namely regarding floors and roofing (which was mainly the result of infiltrations) and the necessity to adapt the building to the current standards of comfort, led to the demolition of significant parts of the existing internal walls.
It was understood that the new structural solution should, as far as possible, be a simple one yet able to respond to the challenge of new weights and overweights while reflecting an alignment with the existing structure, thus avoiding heavy structural reinforcements or foundations.
A light wooden structure has therefore been envisaged, composed by beams and wooden panels for all the roofing. In the main building, this structure was executed through a sheath of mounted mortar connected through the interior of the walls that have been preserved. In order to guarantee the adequate functioning of the structure over the horizontal actions, all of the brickwork has been reinforced.
The most recent quality standards of structural behaviour and durability have been taken into account in the global conception of the structure and in the dimension of its elements, in addition to structural security and economy aspects.
The structural conception has been executed in order to maximise the diverse structural systems that contribute to the general stability, being that the adopted measure for the thickness of the slabs and for the beams’ dimension is fundamentally justified by its good structural behaviour, namely regarding its deformability and resistance under weight use. The ground floor was established by rigging a rockfill laid on duly compacted terrain.
Taking into account the mentioned conditions and the foundation quotas, direct foundations have been adopted. An admissible tension of 0.20 MPa for the maximum service actions was considered for this project.
Current dimensioning criteria have been adopted, in general, for this type of structure, taking into account the security verifications of the Last Limits and Utilisation States.
A particular attention was devoted to the limitation of deformation, in order to prevent damages in non-structural elements, and to contribute to the efficiency of the structure from the point of view of resistance to horizontal actions.
Beyond the safety aspects, economy, compatibility with the architecture and the efficiency in connection with other topics have also been taken into account.
PAULO ALMEIDA RIBEIRO
Documents considered:
Norma Portuguesa EN 206-1 Betão – Comportamento, Produção, Colocação e Critérios de Conformidade.
LNEC E464 – Betões, Metodologia Prescritiva Para uma Vida Útil de Projeto de 50 e de 100 Anos Face às Ações Ambientais Regulamento de Segurança e Ações em Estruturas de Edifícios e Pontes, RSA.
Regulamento de Estruturas de Betão Armado e Pré-Esforçado, REBAP.
Eurocódigo 3, Projeto de Estruturas Metálicas, Parte 1.
Eurocódigo 5, Projeto de Estruturas de Madeira, Parte 1 e 2.
