Open Access

ARTICLE

Experimental Study on the Mechanical Performance of Mortise-Tenon Joints Reinforced with Replaceable Flat-Steel Jackets

Hongmin Li^1,*, Hongxing Qiu², Wenbo Wang³

1 Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Materials Science and Engineering, Nanjing Forestry University, Nanjing, 210037, China
2 Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, Southeast University, Nanjing, 210096, China
3 GuangDong Architectural Design Research Institute Co., Ltd., Guangzhou, 510000, China

* Corresponding Author: Hongmin Li. Email:

Journal of Renewable Materials 2021, 9(6), 1111-1125. https://doi.org/10.32604/jrm.2021.014722

Received 23 October 2020; Accepted 27 November 2020; Issue published 11 March 2021

Abstract

The mortise-tenon joint is an important hub transmitting and distributing external loads for load-bearing components (beams, columns et al.) in the ancient-timber frame structure system. However, the conventional steel hoop reinforcement methods often insert wood screws into the timber components. When the reinforced joint rotates greatly, the anchoring failure of the screws will cause damage to the timber joint. To solve this problem, this study proposes a detachable and replaceable non-destructive flat-steel jacket reinforcement method in which horizontal flat steel is placed in the center of the joint, and the bolt is extended to the outside of the timber beam. Nine 1:3.52 scaled straight-tenon joint specimens were subjected to monotonic loading of beam ends, including three unreinforced reference joints, three joints with flat-steel jacket and three carbon fiber-reinforced plastic (CFRP) reinforced joints. The mechanical behaviors of the novel joints with flat-steel jacket were experimentally studied by comparing with those of the joints without strengthening and retrofitted with CFRP, based on the failure modes, the initial stiffness, the ultimate bearing capacity, and the moment-rotation relationship curves. Results indicated that the mortise-tenon joints reinforced with flat-steel jackets maintain the original semi-rigid properties of the unreinforced mortise-tenon joints and can effectively prevent the tenon from pulling out. The initial stiffness and ultimate bearing capacity were improved markedly. The column and beam of the reinforced joints remain intact providing the reference for the practical application of joints reinforcement. The mortisetenon joints reinforced with CFRP lose the semi-rigid properties of the unreinforced tenon -mortise joints. The joints reinforced with CFRP have the largest initial stiffness, while the unreinforced joints have the lowest stiffness. The initial stiffness of the proposed joint is in between the joints reinforced with CFRP and unreinforced joints. The ultimate bearing capacity of the joints reinforced with flat-steel jacket is larger than the other two joints, whereas the unreinforced joints have the lowest ultimate bearing capacity.

---

Keywords

---