A simplified procedure for non−linear design of the metal connectors in XLam timber walls subjected to gravity and lateral loads

In this paper, a non−linear methodology for the design of the metal connectors in cross−laminated (XLam) timber walls subjected to bending and axial force is presented. The wall is regarded as rigid, and an elastic−perfectly plastic response is considered for each metal connector (hold−down, angle brackets) at the base of the wall. The wood is conservatively modelled with an elastic−brittle behaviour in compression at the interface with the foundation or with the supporting timber floor panel. The force distribution in the metal connectors is obtained by iteratively calculating the neutral axis position at the base of the wall using a simple purposely developed Excel spreadsheet. Five different failure mechanisms at Ultimate Limit States have been identified, starting from the fully tensioned wall to the fully compressed one. The required input parameters are the strength class of timber and the ultimate displacement, the elastic stiffness and the ultimate strength of the metal connectors used. As a result, the algorithm calculates, for every axial load value, the ultimate resisting moment of the entire wall. This procedure, of simple and straightforward implementation, allows the designers to perform a manual evaluation of the rocking resistance of XLam walls in seismic analyses.