Floating column mechanism experimental investigation in historic timber buildings subjected to decay for seismic resilience

Traditional wooden structures are characterized by the presence of a column base that seems to be floated above the foundation stone. This study used pseudo-static experiments to assess the seismic performance of flat pendulum floating resting columns, focusing on the decay and repair of the wood frame (WF). First, an artificial method was used to simulate fungal decay damage of column-foot joints, and filling reinforcement was applied to the decayed column-foot joints, and second, according to the design method in the Sung dynasty architecture, the Ying-tsaofa-shih (building standards). This study presents the findings of pseudo-static tests that were conducted at Yangzhou University. Three 1:3.52 scaled specimen WFs with flat-pendulum-floating-shelf (FPFS)-typed (Ping-bai-fu-ge) columns, i.e., non-damaged WF (named after NT), considering the damaged WF (named after DF) and strengthening damaged WF (named after DR) with one-way straight mortise-tenon joints (OWSMT) joints were made and subjected to cyclic lateral loads during testing. The properties of the WFs with FPFS columns, such as the failure mode, hysteretic and envelope curves, strength and stiffness deterioration, and energy dissipation, have been studied. Finally, the effects of additional damage and reinforcement measures on the seismic performance of WFs are analyzed and compared with the finite element numerical simulation results. This research shows that damage to the column foot decreases the WF's seismic performance, although filler reinforcement may increase it. The foot and mortise joints are interconnected and interact in the wood frame's seismic stressing mechanism. Foot decay reduces the seismic performance of the foot joint, hence increasing the seismic energy dissipation activity of the mortise joints.