TIMBER CARPENTRY WITHOUT STEEL CONNECTORS

Use in modern timber constructions of wood-wood connections inspired by traditional timber carpentry can take advantage today of the many available digital technologies aiding stress analysis and automated control of machining tools. Such methodologies of more recent introduction, if properly employed, allow for a reduction in time and of human error in the design and manufacturing phases of timber structures. Wood-wood connections without metal elements are encountered in many historical buildings. However, not infrequently in intervention on existing timber elements as well as in new timber constructions, the original connection typologies are renounced in favor of other connection typologies due to higher costs and the difficulty of thoroughly analyzing the structural behaviour of wood-only joints under the full set of loading conditions and design seismic actions prescribed by the building regulations currently in force. The connection typologies between timber elements may differ according to the loading types (stress-resultant) for which they are designed to. The most common are carpentry joints and mechanical joints. The former is the traditional union of timber carpentry using woodworking of contacting surfaces. Mechanical joints provide, instead, for the use of metal connections and/or glue layers. Fostering the use of wood-wood connections brings several advantages: (i) exploring the value of timber-timber connections as an ancient cultural heritage amenable to provide methodologies suitably implementable in the design processes of the modern construction industry, with a specific view towards the rehabilitation of historical and monumental buildings; (ii) understanding by parametric computer-aided analyses, in desirable retracing of the past rules of the art, the influence of wood fiber orientation also in the use of engineered composite timber assemblies like CLT; (iii) foster the use of local wood; (iv) measure the fire-resistance of timber joints. This contribution has the twofold purpose of summarizing the state-of-the-art in the structural design of a wood carpentry joint in absence of strengthening metal connectors and exploring the possibilities offered by an ad-hoc stress analysis software for the parametric finite-element analysis of timber joints.