Experimental and Theoretical Investigation of Rotational Behavior of Straight Mortise-Tenon Joints Considering Local Compression Perpendicular to Grain

This paper comprehensively investigates the moment-rotation relationship of straight mortise-tenon joints commonly used in Chinese antique timber buildings, focusing on analyzing the local compression mechanism at the tenon end-mortise and the tenon neck-mortise contact areas. Different compression tests were performed, and the experimental compressive stress-strain curves displayed a typical bi-linear response comprising an elastic increasing response followed by a plastic stage. The specimens subjected to middle local compression tests exhibited higher yield stress, elastic modulus, and plastic modulus than the others. Cyclic loading tests were conducted on twelve mortise-tenon joints with varying lengths, widths, and heights of the tenon to investigate the rotational behavior of the joints under alternating loading directions. The hysteresis curves of the tested specimens generally showed a “Z” shaped pinching effect, indicating limited energy dissipation of the joints during cyclic loading. The length and width of the tenon were observed to have a significant influence on the joint rotational behavior. Finally, a theoretical model was proposed to predict the moment-rotation relationship of the mortise-tenon joint, considering the proposed bilinear stress-strain relationship for wood under compression perpendicular to the grain. The predicted results obtained by the proposed theoretical model were generally validated by the experimental results.