Lateral performance of traditional Chinese penetrated mortise-tenon frames: Experimental and numerical simulation

Abstract

The timber frame is the primary lateral load-resisting component in traditional Chinese timber structures. However, its limited lateral performance may lead to significant structural damage or even collapse under seismic action. Three scaled specimens of penetrated mortise-tenon frame (PMTF) were fabricated and tested under low-cyclic reversed loading to evaluate the lateral performance. This study investigates the failure modes, hysteretic behavior, skeleton curves, stiffness degradation, energy dissipation, and deformation capacities of the PMTF specimens. Based on the experimental results, a restoring force model that accounts for stiffness degradation is proposed for the PMTF. A numerical analysis model of the PMTF was established in OpenSees and validated through comparisons with experimental data. Dynamic analyses were conducted to assess the seismic performance of the PMTF. The results indicate that failure in the mortise-tenon joints primarily manifests as the longitudinal splitting of the timber at the tenon section change, tenon compression deformation, and mortise cracking. During cyclic loading, tenon pull-out becomes particularly noticeable, with a maximum pull-out length of approximately 23.68 mm. The hysteresis curve of the PMTF exhibits a reverse “Z” shape, demonstrating pronounced pinching behavior. As lateral displacement increases, the plastic deformation between the tenon and mortise and the longitudinal splitting of the timber at the tenon section change both intensify, leading to a significant reduction in the lateral stiffness of the PMTF. The established numerical analysis model accurately simulates the hysteretic behavior of the PMTF. The PMTF exhibits superior seismic performance and energy dissipation ability, with inter-story drift angles of 2.23 % and 2.25 % under MCE conditions, respectively. Additionally, the dynamic analysis results show that both the column height and the axial load at the column top significantly influence the seismic performance of the PMTF.