Techno Press

Steel and Composite Structures   Volume 18, Number 5, May 2015, pages 1083-1101
Shear strength analyses of internal diaphragm connections to CFT columns
Liping Kang, Roberto T. Leon and Xilin Lu

Abstract     [Full Text]
    Previous theoretical equations for the shear capacity of steel beam to concrete filled steel tube (CFT) column connections vary in the assumptions for the shear deformation mechanisms and adopt different equations for calculating shear strength of each component (steel tube webs, steel tube flanges, diaphragms, and concrete etc.); thus result in different equations for calculating shear strength of the joint. Besides, shear force-deformation relations of the joint, needed for estimating building drift, are not well developed at the present. This paper compares previously proposed equations for joint shear capacity, discusses the shear deformation mechanism of the joint, and suggests recommendations for obtaining more accurate predictions. Finite element analyses of internal diaphragm connections to CFT columns were carried out in ABAQUS. ABAQUS results and theoretical estimations of the shear capacities were then used to calibrate rotational springs in joint elements in OpenSEES simulating the shear deformation behavior of the joint. The ABAQUS and OpenSEES results were validated with experimental results available. Results show that: (1) shear deformation of the steel tube dominates the deformation of the joint; while the thickness of the diaphragms has a negligible effect; (2) in OpenSEES simulation, the joint behavior is highly dependent on the yielding strength given to the rotational spring; and (3) axial force ratio has a significant effect on the joint deformation of the specimen analyzed. Finally, modified joint shear force-deformation relations are proposed based on previous theory.
Key Words
    joint behavior; CFT columns; shear capacity; shear deformation mechanism; finite element analysis; shear force-deformation relations
(1) Liping Kang, Xilin Lu:
State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, 1239 Siping Rd. Shanghai 200092, P.R. China;
(2) Roberto T. Leon:
Via Department of Civil and Environmental Engineering, Virginia Tech, 750 Drillfield Drive, Blacksburg, VA 24061, USA.

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