Structural Behavior of CHS T-Joints Subjected to Static In-Plane Bending in Fire Conditions
Publication: Journal of Structural Engineering
Volume 142, Issue 3
Abstract
Fire resistance of steel joints is always a major concern in the design of steel structures under extremely hazardous conditions. However, for circular hollow section (CHS) joints in fire conditions, little information is available, especially for T-joints. To gain more insight into the static behavior of CHS T-joints in elevated temperatures, experimental and numerical studies were conducted on selected T-joints subjected to in-plane bending. The failure modes and ultimate strength of the joints subjected to different temperatures were investigated and compared to the corresponding joints at ambient conditions. Within the range of investigated parameters, at 700°C, the joint strength was reduced to 22.1% compared to the corresponding joint at ambient temperature. Furthermore, it is observed that at high temperatures, a change occurred in the failure mode of the joints. Cracks formed around the center weld toes before the joints reached excessive deformation, which subsequently affected the joint postyield hardening performance. To understand the initiation of the cracks, a material test was performed. The fracture strains of the heat-affected zone of the chord material beneath the center weld at corresponding temperatures were determined. The fracture strains were included in subsequent finite-element (FE) validation models. The verified finite element analysis models were used to analyze the structural behavior of CHS T-joints at elevated temperatures, such as strain, stress, load path, and effect of fracture strains, to gain insight into the failure mechanism of the joints.
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Acknowledgments
This research was funded by the ARC 2/07 project entitled “Failure modes and ultimate strength of tubular joints under elevated temperatures” from the Ministry of Education, Singapore.
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Published In
Journal of Structural Engineering
Volume 142 • Issue 3 • March 2016
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Apr 10, 2014
Accepted: Jun 23, 2015
Published online: Oct 27, 2015
Published in print: Mar 1, 2016
Discussion open until: Mar 27, 2016
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