An innovative slip-friction moment-resisting connection using screwed-in threaded rods in cross laminated timber and steel coupling parts: An experimental study
Osama Abdelfattah Hegeir, Kjell Arne Malo, Haris Stamatopoulos
Abstract
Moment-resisting frames provide open space and architectural flexibility, yet their application in multistorey timber buildings is limited. Research on the pullout behaviour of threaded rods screwed into timber has demonstrated high strength and stiffness. This paper presents an innovative, slip-friction, beam-to-column, moment-resisting connection, which utilizes threaded rods screwed into cross laminated timber beams and columns. The connection employs the concept of slip-friction, which has been successfully used in several steel structures and allows for energy dissipation though friction slip, hence realize a damage free energy dissipation mechanism. Four full-scale tests have been carried out, in which specimens have been first subjected to service-level cyclic loading, followed by a destructive cyclic loading. Under service-level cyclic loading, the connection featured stiffness in the range of 10,000–20,000 kNm/rad and approximately 4 % equivalent viscous damping ratio. Under destructive cyclic loading, the connection exhibited high moment capacity in the range of 164–180 kNm. Furthermore, ductile behaviour was observed with failure associated with plastic hinging in the threaded rods. Ductility ratios were estimated based on cyclic envelop curves and found to be in the range of 4.0–6.6.