Seismic response of traditional dissipative connections for multi-storey cross-laminated timber buildings: a framework for the assessment of limitations and potentialities

This doctoral thesis investigates the mechanical behaviour and seismic performance of traditional dissipative connections used in Cross-Laminated Timber (CLT) structures through a framework combining experimental investigation, analytical interpretation, and numerical analysis. Initially, a state-of-the-art review of 53 experimental campaigns was conducted to systematise knowledge on traditional connections, specifically hold-downs, angle brackets, and panel-to-panel joints. This analysis identified recurring trends in mechanical performance and failure mechanisms, resulting in an annotated catalogue that serves as a reference database for further evaluations. Five experimental campaigns were then carried out in collaboration with Rotho Blaas s.r.l. to investigate traditional and newly developed second-generation 3-D mechanical anchors under monotonic and cyclic loading. Characterisation followed EN 26891 and EN 12512 protocols, integrating criteria from the forthcoming second-generation Eurocode 8 and Technical Specification FprCEN/TS 1998-1-101. A significant outcome was the development of second-generation hold-downs designed to overcome brittle failures typical of first-generation products by optimising their geometrical characteristics. The research further examined Capacity-Based Design (CBD) principles to ensure ductile mechanisms while preventing brittle failure in CLT shear-walls. Particular focus was placed on the analytical definition of brittle modes, such as plug-shear in CLT panels and anchorage failure in concrete foundations, identifying governing parameters and quantifying strength capacity. Finally, a comprehensive multi-parametric numerical study, comprising 5145 2-D CLT shear-wall configurations, was performed using TimberTech Buildings software. The analysis evaluated the combined influence of seismic intensity (ag), number of storeys (N), shear-wall to floor area ratio (ρ), and segment-length variability (Ω) on connection demand. These results were validated through 3-D case-study models and synthesised into a chromatic performance classification framework. This tool visually correlates seismic demand with connection capacity, providing a design-oriented support for the selection of appropriate connection systems in multi-storey CLT buildings.