Seismic performance evaluation of mass timber buildings equipped with resilient and conventional friction devices

The application of mass timber elements in different structures has gained publicity over the last few years, primarily due to climate change adaptation policies and net zero carbon targets. Timber is a renewable construction material that can outperform other building materials regarding environmental impact. However, when used in seismically active regions, its application has been limited due to the uncertainties on their seismic behaviour in respect with different design standards and limited ductility in conventional connections. Conventional timber connections typically suffer from stiffness and strength degradation under cyclic loads. Their repairability is also low due to permanent damage in the fasteners and the associated crushing in the wood fibres. The use of friction connections can be an efficient way to mitigate these issues. They offer many advantages as they are economical and yet provide a high level of reliable and continuous energy dissipation. In recent years, a new generation of friction connections has been developed that can provide self-centring behaviour (i.e., the ability of the structure to return to its original position at the end of an earthquake). However, how these connections perform compared to a mass timber system with conventional timber connections is still unknown.

Several studies in the literature have suggested that these connections can enhance the performance of mass timber structures. However, the seismic performance of such systems specifically in terms of base shear, response drifts and response accelerations—has not been thoroughly investigated. This paper examines various design aspects of conventional friction connections and self-centring friction connections, providing insights into their differences concerning key seismic performance indicators. It compares the seismic performance of mass timber buildings equipped with both solutions, highlighting their advantages and limitations and drawing conclusions based on the results. The key findings are that friction connections can provides a superior seismic performance for timber structures. However, that may need to be combined with a parallel system avoid residual displacements.