Experimental Investigation and Theoretical Analysis of Friction Damped Self-Centering Timber Frame Considering Compression Perpendicular to the Grain

Abstract The posttensioned (PT) self-centering timber frame exhibits minimal residual deformation after undergoing significant deformation, which has attracted considerable attention. However, the low compressive strength of timber perpendicular to the grain and the loss of PT force significantly impact the seismic performance of self-centering timber frame structures. Therefore, this research reveals the hysteretic mechanisms by considering the compressive characteristics of timber in the transverse direction, the loss of PT force, the parameters of the energy-dissipating device, and the characteristics of the self-centering components based on the investigation of a self-centering timber frame, which is equipped with web friction energy-dissipating devices and locally strengthened beam-column joints. Based on cyclic loading tests and theoretical analyses conducted on seven specimens with varying parameters, the theoretical prediction method for the compression deformation of columns perpendicular to the grain after gap opening was proposed. It also reveals the influence mechanism of locally strengthened components in beam-column joints, including reinforcement plates and steel angles, on structural stiffness and load capacity. Finally, the loss of PT force and preloading force applied to the friction bolts, along with the damage modes of beam-column joints, were investigated. Results demonstrate that all specimens exhibited typical flag-shaped hysteresis behavior, and at 2.0% drift, they showed expected energy dissipation and self-centering performance. When the preloading force applied to friction bolts is designed to be approximately 27% of the timber’s perpendicular compressive strength, the loss of this force can be minimized. The arrangement of reinforcement plates and steel angles improves connection stiffness and effectively prevents extensive damage to timber columns. The derived theoretical formula for compression deformation perpendicular to the grain aligns well with experimental results, offering reliable predictions for damage indicators in these frames. Additionally, the theoretical model analyzes the effects of PT force and friction on compression deformation at large drifts, leading to the proposal of an ultimate moment contribution ratio, λ ult , with λ ult > 5 recommended to ensure self-centering performance and limit timber damage perpendicular to the grain at maximum gap opening.