q-factor estimation for 3D log-house timber buildings via Finite Element analyses

The paper numerically investigates the structural response of log-house (or log-haus, Blockhaus, etc.) timber buildings under seismic loads. The typical log-house system consists of a series of timber members, stacked horizontally one upon another. There, the mechanical interaction is given by traditional timber joints with carvings, multiple contact surfaces, friction phenomena. Even though log-house systems are widely used for the construction of wooden houses or commercial buildings in earthquake-prone regions, no design provisions are currently given in design standards. In this paper, a Finite Element (FE) numerical investigation is performed in ABAQUS on full three-dimensional (3D) log-house buildings subjected to seismic loads, as an extension of past studies focused on single components and walls only. In the typical FE model, the cyclic behaviour of carpentry joints at the interception between multiple logs and walls is properly accounted, including frictional effects and possible tolerance gaps due to the construction process. Nonlinear dynamic analyses are carried out on a set of selected building configurations of technical interest for design, giving evidence of their structural performance. Based on the so collected parametric FE results, estimations of the q-behaviour factor are hence discussed. As shown, the FE data suggests that - compared to other timber structures - a larger inter-storey drift should be considered for the seismic design of log-house buildings. In addition, the same FE results show that a q-behaviour factor up to 2.8 can be accounte