Dynamic properties of glued laminated timber beams with finger-joints subjected to impact loading

As mass timber construction grows in scale and complexity, understanding its response when subjected to highly dynamic loading is essential. While rate-dependent material behaviour is well characterised for steel and reinforced concrete, corresponding material models for timber remain limited. Existing design standards and guidelines typically rely on constant dynamic strength increase or simplified load-duration factors, which may under- or overestimate the ultimate resistance in short duration, high strain rate events. This study conducted 36 full-scale pendulum impact hammer tests on spruce glued laminated timber beams with finger-joints at ETH Zurich, varying beam length and impact velocity to achieve strain rates between 0.50 and 2.00 s -1 . The results, combined with data from literature, enabled the calibration of a Cowper–Symonds power law for glued laminated timber. Dynamic strength increase factors ranged from 1.00 to 1.70. Energy-based analyses revealed substantial energy dissipation, with specimens absorbing five to eight times the elastic strain energy in the post-peak phase. These findings provide a robust basis for rate-dependent modelling of timber subjected to impact loading and may inform improved application of dynamic strength increase factors in design standards and guidelines. The quantification of the energy dissipation enables performance-based design of timber subjected to impact loading, supporting controlled member rupture while ensuring full dissipation of the impactor’s kinetic energy. • 36 pendulum impact hammer tests were conducted on glued laminated timber beams. • A set of equations were developed to quantify inertial and shear effects. • With data from existing literature, a Cowper–Symonds power law was calibrated. • The mean dynamic strength increase factors vary between 1.00 and 1.70 • An idealised softening ratio was proposed and quantified.