Seismic Behaviour of Prestressed Timber Columns under Bi-directional Loading
Structural members made of laminated veneer lumber (LVL) in combination with unbonded posttensioning have recently been proposed, which makes it possible to design moment-resisting frames with longer spans for multi-storey timber buildings. Moreover, prefabricated and prestressed timber buildings can be designed to have enhanced re-centering and energy dissipation characteristics for seismic resistance. The post-tensioning provides re-centering capacity while energy is dissipated through the addition of special dissipating devices. As part of a research program on timber structures, experimental and analytical studies have been performed to investigate response of prestressed LVL columns under bi-directional seismic loading. The results show excellent seismic performance, characterized by negligible damage of the structural members and small residual deformations, even under the combined effect of loading in two directions. Energy is dissipated mostly through yielding of external mild steel axial dissipators connecting the column and the foundation, which can be easily removed and replaced after an earthquake. Since post-tensioning can be economically performed on site, the system can be easily implemented in multi-storey timber buildings.