Timber structures have gained interest for the construction of mid-rise buildings, but their seismic performance is still a matter under development. In this study, a numerical analysis of the seismic performance of light-frame timber buildings is developed through a highly detailed model using parallel computing tools. All of the lateral-load-resisting system components and connections are modeled. Combinations of lateral load capacity distributions in structures of one, three, and five stories are studied in order to assess the effects on the global performance of different triggered failure modes through nonlinear static and dynamic analyses. The results suggest that shear bracket connections and sheathing-to-framing connections control the buildings’ responses, as well as the failure mode. For a ductile response, the lateral displacement must be dominated by the in-plane wall distortion (racking); therefore, the system must be provided with a story shear sliding stiffness and load capacity at least twice that of the walls. Furthermore, based on the pushover capacity curves, the performance limits are proposed by evaluating the stiffness degradation. Finally, the effect of the mobilized failure mode on the structural fragility is analyzed. Even though standard desktop PCs are used in this research, significant reductions in the computation effort are achieved.

Timber construction experiences a growing trend in different countries due to its inherent environmental benefits and proven lateral load performance. However, most of the previous studies on structural and seismic performance have focused on undamaged structures without any signs of deterioration. This paper focuses on the analysis of the effects of the initial damage state on the seismic response and fragility of a five-story CLT building designed under a force-based approach. A detailed 3D finite element model was developed and validated through experimental data in order to perform incremental dynamic analyses that considered different arbitrarily imposed initial damage states. The residual response and the fragility functions are analyzed to characterize the impact of the initial state on seismic behavior. The results of this work highlight the need to properly consider the effect of previous load actions for the seismic performance evaluation during the operating life of CLT structures. Findings suggest that the initial state can significantly modify the probability of reaching a given limit state. Moreover, it was found that if the initial damage is defined as severe, the collapse margin ratio is reduced by 58.8% compared to the case in which the initial state is undamaged.

Buildings constructed with cross-laminated timber (CLT) panels have been gaining international interest in recent years, mainly due to their sustainability and industrialization attributes. However, there are still doubts about the stability of the dynamic properties of this type of building over time, as wood undergoes dimensional changes due to variations in temperature and relative humidity. The objective of this study is to evaluate the variability of the dynamic properties of a 5-story CLT building prototype over 2 years. The dynamic properties of the CLT building were estimated through a 2-stage process. In the first stage, accelerometers were installed on various floors of the building, and the vibrations induced by the environment were recorded 96 times a day over a two-year period. Then, in the second stage, each acceleration record was processed using the Stochastic Subspace Identification method (SSI) to estimate the two fundamental frequencies of lateral vibration of the building. The results showed that the lateral frequencies of the CLT building were 9% lower in summer than in winter. This phenomenon correlated positively with measurements of the moisture content of the wood in the CLT walls. In other words, as the moisture content in the CLT panels decreased, volumetric contractions occurred in the panels, and there was less interlocking at the joints between panels, resulting in lower lateral stiffness for the building. These results are expected to contribute to regulatory updates in Chile and to the probabilistic calibration of future numerical models of this building.