Tabique is one of the main Portuguese traditional building techniques which use raw materials as stone, earth and wood. In general, a tabique building component as a wall consist of a wooden structure made up of vertical boards connected to laths by metal nails and covered on both sides by an earth based material. This traditional building technology as an expressive incidence in the Alto Douro Wine Region located in the interior of Northern Portugal, added to the UNESCO's Word Heritage Sites List in December 2001 as an 'evolved continuing cultural landscape'. Furthermore, previous research works have shown that the existing tabique construction, in this region, reveals a certain lack of maintenance partially justified by the knowledge loosed on that technique, consequently this construction technique present an advanced stage of deterioration. This aspect associated to the fact that there is still a lack of scientific studies in this field motivated the writing of this paper, the main objectives are to identify and characterize the nails used in the timber connections. The nails samples were collected from tabique walls included in tabique buildings located in Lamego Municipality, near Douro River, in the Alto Douro Wine Region. This work also intends to give guidelines to the rehabilitation and preservation of this important legacy.

Abstract:The Alto Douro Wine Region, located in the northeast of Portugal, a UNESCO World Heritage Site, presents an abundant vernacular building heritage. This building technology is based on a timber framed structure lled with a composite earth-based material. A lack of scienti c studies related to this technology is evident, furthermore, principally in rural areas, this traditional building stock is highly deteriorated and damaged because of the rareness of conservation and strengthening works, which is partly related to the non-engineered character of this technology and to the knowledge loosed on that technique. Those aspects motivated the writing of this paper, whose main purpose is the physical and chemical characterization of the earth-based material applied in the tabique buildings of that region through eld tests. Consequently, experimental work was conducted and the results obtained allowed, among others, the proposal of a series of adequate eld tests. At our knowledge, this is the rst time eld tests are undertaken for tabique technology. This information will provide the means to assess the suitability of a given earthbased material with regards to this technology. The knowledge from this study could also be very useful for the development of future normative documents and as a reference for architects and engineers that work with this technology to guide and regulate future conservation, rehabilitation or construction processes helping to preserve this important legacy.

The Alto Douro Wine Region, a region located in the northeast of Portugal, presents an abundant building heritage which consists of tabique constructions, a vernacular construction technology. This technology uses raw materials such as stone, an earth-based material and wood, besides metal nail sensure the timber connections and the required structural safety. Previous research works have shown that most of the existing tabique buildings, in this region, present signs of marked deterioration and some of them are clearly near collapse. This reality is justified, among others, by the non-engineered character of this construction technology and subsequent loss through time of the associated empirical technical knowledge, consequently, conservation and repairing works are urgently needed. These aspects, added to the dearth of knowledge related to this building heritage have motivated this research work which is focused on studying the nails traditionally applied in those tabique buildings. In this article, and for the first time, a nail geometrical and material characterization is presented and discussed. The results highlight a wide nail dimensional variety, being iron the main chemical element identified. Beyond that, this study demonstrates that those nails should no longer be maintained in service and that new nails should be applied in future conservation and strengthening works. Finally, some guidelines regarding tabique rehabilitation and nail rusting prevention are mentioned.

Existing structures must be adapted to comply with current standards or for space efficiency requirements. This adaptation may include the need to create openings in existing walls. In load bearing walls, the loading path is locally altered and the new path needs to be strengthened. In this paper, a strengthening practice technique based on the introduction of steel beams and steel portal frames and currently applied in Haussmannian buildings and French Alps Ski resort hotels is described. This technique is widely used and applied to walls with different materials and thicknesses or different openings geometry and for a high variety of loadings, presenting acceptable results along time. The knowledge presented in this work is intended to give guidance to numerical and experimental research related to opening strengthening, to strengthening guidelines definition and at the same time to support and encourage the development of innovating wall openings strengthening techniques.

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