Lateral performances of traditional wooden frame with loose penetrated mortise-tenon connection and column foot models

Abstract

Traditional wooden structures in China have free-standing columns on top of stone bases and the beams and columns connected by mortise-tenon joints. Many of them have been in service for hundreds of years withstanding many seismic events, and yet their performances against lateral loadings are not clear. This paper studies the behavior of a wooden portal frame with penetrated mortise-tenon (PMT) connections and column foot (CF) connections under transverse load. An analytical model for a planar loose PMT connection is proposed based on the load-displacement relationship. The mechanical behavior of these loose connections with the friction-slip-contact mechanism is studied with clear evidences of negative stiffness in the lateral resistance of the wooden frame. The different contact states of the PMT and CF connections in the load resisting process are studied. Results indicate that the lateral performances of the wooden frame are dependent on the synergistic action of the PMT and CF connections. The lateral deflection mechanism of a wooden frame is strongly affected by the loose PMT connections and the P-Δ effect of the supporting columns.