This paper deals with research regarding a singular technique adopted by Renaissance carpentry. The technique consists in the assembly of timbers whose size is shorter than the span to cover (and in some cases the span can be quite considerable). The wooden composite beam technique appeared in Ferrara probably in the course of the 15th century as a reasonable way to cover huge and important rooms which otherwise would have required too long and too high one-piece beams, difficult to be provided locally. Usually a wooden composite beam consists of some pieces properly shaped and connected to one another with clinched nails in order to reproduce the unity of the entire beam. The work moves from a historical approach based on the analysis of ancient documents and from “in situ” instrumental surveys. The composite beams are characterised by a mechanical behaviour which is totally different from the one of the traditional one-piece beam: the shape and the mutual position of the pieces forming the composite beam give rise to an internal force diffusion which reminds an arch-like behaviour as described for the first time by Leon Battista Alberti in his De Re Aedificatoria. Moreover detailed surveys have pointed out an upward slope of the intrados one-piece element of such beams, intentionally produced to limit the inflection due to the applied loads, as confirmed by some notes of Leonardo Da Vinci in the “Codice Atlantico” and by the systematic encoding of the 19th century manuals. Therefore the techniques and the building site equipments used to bend, to assemble and to raise the composite beams are also investigated. The numerous measurements carried out to survey the exact geometry of the components and the proportional ratios between them has allowed also to set up a specific survey methodology for such composite beams.
Wooden composite beams: a new technique in the Renaissance of Ferrara
MALVEZZI, Roberto;ALESSANDRI, Claudio;FABBRI, Rita
2003
Abstract
This paper deals with research regarding a singular technique adopted by Renaissance carpentry. The technique consists in the assembly of timbers whose size is shorter than the span to cover (and in some cases the span can be quite considerable). The wooden composite beam technique appeared in Ferrara probably in the course of the 15th century as a reasonable way to cover huge and important rooms which otherwise would have required too long and too high one-piece beams, difficult to be provided locally. Usually a wooden composite beam consists of some pieces properly shaped and connected to one another with clinched nails in order to reproduce the unity of the entire beam. The work moves from a historical approach based on the analysis of ancient documents and from “in situ” instrumental surveys. The composite beams are characterised by a mechanical behaviour which is totally different from the one of the traditional one-piece beam: the shape and the mutual position of the pieces forming the composite beam give rise to an internal force diffusion which reminds an arch-like behaviour as described for the first time by Leon Battista Alberti in his De Re Aedificatoria. Moreover detailed surveys have pointed out an upward slope of the intrados one-piece element of such beams, intentionally produced to limit the inflection due to the applied loads, as confirmed by some notes of Leonardo Da Vinci in the “Codice Atlantico” and by the systematic encoding of the 19th century manuals. Therefore the techniques and the building site equipments used to bend, to assemble and to raise the composite beams are also investigated. The numerous measurements carried out to survey the exact geometry of the components and the proportional ratios between them has allowed also to set up a specific survey methodology for such composite beams.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
