Steel rigid beam-to-column connections strengthened by buckling-restrained knee braces using round steel core bar dampers

• Published in: Engineering structures Vol. 250; p. 113431
• Main Authors: Munkhunur, Togtokhbuyan, Tagawa, Hiroshi, Chen, Xingchen
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.01.2022; Elsevier BV
• Subjects: Bearing capacity; Buckling; Buckling-restrained steel bar damper; Cyclic loading test; Cyclic loads; Dampers; Downsizing; Finite element analysis; Flanges; Knee; Knee brace; Mortars (material); Orthopedic apparatus; Parameters; Performance measurement; Plastic properties; Plasticity; Rigid moment beam-to-column connection; Spreading; Spreading of plasticity; Steel; Weight reduction; Rigid moment beam-to-column connection; Buckling-restrained steel bar damper; Knee brace; Finite element analysis; Spreading of plasticity; Cyclic loading test
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2021.113431

•A study on the spreading of plasticity at the beam ends is in its infancy.•A knee brace consisting of a steel core bar and a tube buckling restrainer is proposed.•The steel core bar downsizes the connections between braces and beams.•The proposed knee braces reduce stress concentration at the beam ends. This paper presents an innovative application of buckling-restrained knee braces (BRKBs) for spreading plasticity at the beam ends of rigid moment connections. A slender knee brace configuration consisting of a steel core bar and tube buckling restrainer is proposed. The benefit of adopting a steel bar is that it enables the downsizing of the knee brace connections between braces and beam flanges. The advantages of tube buckling restrainers include relatively simple implementation for ease of construction and reduced weight compared to mortar-filled buckling restrainers. Displacement-controlled cyclic loading tests were conducted to examine the spreading of the plasticity behaviors of rigid moment connections using the proposed BRKBs. Structural performance metrics such as hysteretic behavior, strength capacity under a given loading, and strain distributions at beam flanges were measured and analyzed in detail. Additionally, the optimal parameters for the proposed BRKBs were determined through an extensive numerical study. The results revealed that the optimal parameters of the proposed slender BRKBs significantly improve load-bearing capacity and reduce stress concentrations in the vicinity of the rigid beam-to-column connections. As a result, the plastic region on the beam is spread both inside and outside the knee brace area. Based on the research conducted thus far, it was determined that the proposed BRKB is a viable option for spreading plasticity along beams in rigid beam-to-column connections.