Climate change and densification of cities are two major global challenges. In the building and construction industry, there are great expectations that tall timber buildings will constitute one of the most sustainable solutions. First, vertical urban growth is energy and resource-efficient. Second, forest-based products store carbon and have one of the highest mechanical strength to density ratios. If the structural substitution of concrete and steel with wood in high-rise buildings awakens fears of fire safety issues, engineers and researchers are particularly worried about the dynamic response of the trendy tall timber buildings. Indeed, due to the low density of wood, they are lighter, and for the same height, they might be more sensitive to wind-induced vibrations than traditional buildings.To satisfy people’s comfort on the top floors, the serviceability design of tall timber buildings must consider wind-induced vibrations carefully. Architects and structural engineers need accurate and verified calculation methods, useful numerical models and good knowledge of the dynamical properties of tall timber buildings.
Firstly, the research work presented hereby attempts to increase the understanding of the dynamical phenomena of wind-induced vibration in tall buildings and evaluate the accuracy of the semi-empirical models available to estimate along wind accelerations in buildings. Secondly, it aims at, experimentally and numerically, studying the impact of structural parameters – masses, stiffnesses and damping – on the dynamics of timber structures. Finally, it suggests how tall timber buildings can be modeled to correctly predict modal properties and wind induced responses.
This research thesis confirms the concerns that timber buildings above 15-20 stories are more sensitive to wind excitation than traditional buildings with concrete and steel structures, and solutions are proposed to mitigate this vibration issue. Regarding the comparison of models from different standards to estimate wind-induced accelerations, the spread of the results is found to be very large. From vibration tests on a large glulam truss, the connection stiffnesses are found to be valuable for predicting modal properties, and numerical reductions with simple spring models yield fair results. Concerning the structural models of conceptual and real tall timber buildings, numerical case studies emphasize the importance of accurately distributed masses and stiffnesses of structural elements,connections and non-structural building parts, and the need for accurate damping values.