Rotational behavior of glulam moment-resisting connections with long self-tapping screws

Abstract

The rotational behavior of beam-column connections plays an important role on the mechanical performance of timber frames. Recently, long self-tapping screws and threaded rods applied as fasteners by virtue of their advantageous withdrawal capacity and stiffness, provide promising technical solutions to achieve beam-column connections with high moment resistance and rotation stiffness. To investigate the rotational behavior of the glulam beam-column moment-resisting connections using self-tapping screws as fasteners, a series of monotonic and low-frequency cyclic loading tests are conducted on a total of ten full-scale specimens with screw inclination as the geometric configuration parameter in this paper. Based on the experimental campaign and results, the moment resistance, rotation stiffness, deformability and energy dissipation capacity of the connections are evaluated. The results indicate that this type of connection is characterized by a high moment resistance and rotation stiffness, but not very considerable deformability and energy dissipation capacity. When the connection fails in the tensile fracture of self-tapping screws, the screw inclination at the range of 15°∼30° has negligible influence on the moment resistance but significant influence on the rotation stiffness. Besides, the connections with 15° screw inclination show larger stiffness, lower ductility, faster degradation of secant stiffness and more rapid growth of equivalent viscous damping ratio compared with the connections with 30° screw inclination.