Numerical analysis of timber log-haus walls with steel dovetail reinforcements under in-plane seismic loads

The paper investigates the structural response and vulnerability of timber log-haus wall under in-plane seismic loads. Careful consideration is given, in particular, to the structural efficiency of additional metal fasteners introduced within the thickness of timber log-walls. Log-haus systems are typically obtained by stacking multiple logs, and generally used for residential or commercial buildings up to two levels. Their seismic characterization, however, still requires further investigations and studies, since current standards for timber structures (i.e. Eurocode 5 and Eurocode 8) do not provide specific recommendations for their seismic design. In this regard, the so called steel dovetail profiles are aimed to improve the in-plane stiffness and ultimate resistance of traditional timber log-walls. Taking advantage of past experiments carried out on small-scale joint specimens, as well as past 3D numerical efforts, in this paper full 3D solid models are described in ABAQUS, to assess the potential of steel dovetail profiles, as well as to capture possible issues. Numerical simulations are proposed both for small-scale specimens as well as full 3D assemblies, being representative of the actual loading and boundary conditions for log-haus walls as part of a real building. As such, the effect of key input parameters and main influencing aspects is emphasized. Based on the rather close correlation between experimental and numerical results, as well as on the well promising effects and benefits due to the proposed reinforcement technique, the same numerical study has been further extended. To this aim, full log assemblies well representative of the actual boundary and loading condition of logs being part of a real building have been analyzed. As shown, also in accordance with past numerical investigations and outcomes, the overall in-plane response of such systems typically depends on a combination of multiple aspects, including small gaps within the carpentry joints as well as the compressive load level and possible damage mechanisms occurring in all the interacting structural components. In any case, as emphasized in the paper, the examined steel dovetails can have beneficial effects on the seismic response of traditional log-haus walls. In this regard, it is hence expected that current FE outcomes could be useful for full optimization of the proposed enhancement technique.