Timber Beam-to-Column Joint With Steel Link: Design and Mechanical Characterization Through Numerical Investigation

Abstract

For the design of dissipative heavy timber frame structures, in the context of modern seismic design approach based on the mechanical triad of strength, stiffness and ductility, brittle timber failure modes can be avoided by integrating hybrid timber-steel system into modern timber connection technology. Thus, the overall seismic performance of timber structures can be improved, entrusting the dissipation function to ad hoc conceived devices, like steel links. With reference to the structural type of Moment Resisting Frames (MRF), steel links located at the ends of the beams are able to provide a significant dissipative capacity, by means of cycles of plastic deformations, while timber members and steel connections, to be designed with an adequate overstrength as respect to the link, behave in elastic field. In this regards, the paper presents the capacity design and the mechanical characterization through monotonic numerical analyses of two different timber beam-to-column joint with steel link for MRF structures, consisting of a timber beam and a steel link connected each other by means of a stiffened end-plate and glued-in steel rods. The proposed design criteria of the joint are validated through the evaluation of performance, by means of nonlinear pushover analyses on the joint refined FEM models, in terms of key parameters, such as ultimate resistance, stiffness, rotation capacity and failure modes. The numerical results confirm the plastic deformation of the link, which large dissipative capacity of the joint corresponds to.

A Proposal for the Mechanical Classification of Beam-to-Column Joints for Timber Structures

“…It is also worth to notice that timber members sizes can be determined by the number and type of connectors rather than by the strength requirements for members. With regards to Moment Resisting Frames (MRF), several experimental studies have been recently carried out on common timber beam-to-column joints, aimed at evaluating the strength and stiffness capabilities [1][2][3][4][5][6][7][8][9]. However, both in national and international standards, there is not a method that allows to identify the mechanical behaviour of timber connections.…”