Influence of the earthquake and progressive collapse strain rate on the structural response of timber dowel type connections through finite element modelling

Abstract

This paper aims at understanding the influence of the strain rate, as those experienced under earthquake and progressive collapse events (referred to as “medium” strain rates), on the structural response of metal dowel type timber connections through the development of a finite element model. Past studies on timber connections have been mainly performed under quasi-static loadings. However, as metal and timber show different degrees of sensitivity to increased strain rate, such connections may exhibit different dynamic failure modes and load-carrying capacities than quasi-statically. To understand this phenomenon, a finite element model for dowel type timber beam-to-column connections, having a T-section aluminium bracket, was developed in this study. The model was validated incrementally, against (1) quasi-static and dynamic embedment tests, (2) single bolted connection quasi-static shear tests and (3) complete dowel type connection quasi-static shear and bending tests. Material properties under medium strain rates were then applied to the static model to study the structural response of the studied connection during earthquake and progressive collapse events. It was found that the change in material properties only contributes to a slight increase in capacity (up to 6.5%) but insignificant variations in initial stiffness (less than 4.1%) for the studied connection. This indicates that the connection can be safely designed statically for earthquakes and progressive collapse events. The methodology proposed in this paper and the finite element model developed can be extended to other types of timber connections.