Design and testing of a dissipative connection for XLam buildings

The paper describes the design process and experimental testing of an innovative dissipative connection suitable for XLam buildings in seismic areas. As XLam technology provides the use of massive timber shear walls characterized by low dissipative capabilities, an efficient connection system with ductile behaviour is essential in order to avoid brittle failure and to increase energy dissipation capability under seismic action. Hold-down and angle-bracket connections were originally developed for platform-frame constructions, and then adopted also in XLam structures. When such elements are subjected to cyclic and/or combined forces, they show reduced strength and unfavourable brittle behaviour. Therefore, a new generation of dissipative connections for specific usage in XLam structures is required. The proposed connection element was designed to allow large and very ductile hysteretic behaviour even under combined loading. A suitable over-strength is assured on the wood side in fulfilment of capacity design criteria. The characterization of the proposed connector was first conduced via numerical FE modelling and then supported by cyclic-loading tests according to EN 12512 protocol. Experimental results allowed to verify the actual mechanical parameters (i.e., strength, stiffness and ductility) and to obtain a comparison with a traditional connection system.