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Behavior of structural steel moment connections under fire loading

Published

Author(s)

Mina S. Seif, Joseph Main, Fahim H. Sadek

Abstract

Performance-based methodologies to evaluate the fire performance of structures are needed to move beyond the prescriptive procedures presently in use. Analytical methods are needed for simulating the performance of structural systems, including connections, subject to realistic fire effects. Framing connections may be subject to large unanticipated deformations and loads during fire events, and connection failure may lead to other failures or local collapse. In this study, the performance of steel moment frames under fire-induced heating was investigated using detailed finite-element modeling. Models of two types of seismically designed steel moment frames were developed, including an intermediate moment frame with welded unreinforced flange, bolted web (WUF-B) connections, and a special moment frame with reduced beam section (RBS) connections. Assemblies consisting of two columns and a single beam span were modeled, with highly refined modeling of the connection regions. Structural analyses were performed under gravity loads in combination with a thermal loading scenario consisting of a heating phase followed by a cooling phase. Recently developed temperature-dependent material models for structural steel and bolts that incorporate erosion-based modeling of fracture were implemented in the study. The influence of axial restraint on the performance of the moment frames was investigated by considering different support conditions for the end columns. Local buckling in the connection region was observed in the heating phase of the analyses, with buckling occurring at lower temperatures under more highly restrained conditions. Subsequent to local buckling, substantial tensile forces were developed in the beams during the cooling phase.
Proceedings Title
Proceedings of the Annual Stability Conference
Structural Stability Research Council
Nashville, Tennessee
Conference Dates
March 24-27, 2015
Conference Location
Nashville, TN, US
Conference Title
Annual Stability Conference
Structural Stability Research Council

Citation

Seif, M. , Main, J. and Sadek, F. (2015), Behavior of structural steel moment connections under fire loading, Proceedings of the Annual Stability Conference Structural Stability Research Council Nashville, Tennessee , Nashville, TN, US, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917821 (Accessed November 30, 2021)
Created March 23, 2015, Updated October 12, 2021