Analysis, Design & Performance
Full Session with Abstracts
338904-5 - Stability under Fire Loads: A New Chapter in the Guide to Stability Design Criteria for Metal Structures
Saturday, April 21
8:00 AM - 9:30 AM
Mina Seif, PhD, PE
Research Structural Engineer
National Institute of Standards and Technology (NIST)
As the fire engineering industry moves towards performance-based design, practitioners will require more guidance (codes, standards, and guides) to design structures for fire loads. This guidance should incorporate the state-of-the-art research in a practical manner. In recent years, Task Groups and Committees of various organizations (e.g. ASCE, AISC, and SSRC) have focused their efforts on developing and expanding guidelines. These guidelines bridge the gap between state-of-the-art research and the structural engineering profession.
The Structural Stability Research Council’s (SSRC) 'Guide to Stability Design Criteria for Metal Structures' is a reference for practicing structural engineers and researchers to design metal structures for stability. This guide addresses many different stability-related topics, including stability issues under extreme loading conditions (i.e. earthquake, disproportionate collapse). Stability is proven paramount to the performance of steel structures under fire. Therefore, the upcoming seventh edition of the SSRC Guide will include a new chapter on “Stability under Fire Loads”. This new chapter is authored by Task Group - TG06: Stability under Extreme Loads - which the lead author of this paper chairs.
The “Stability under Fire Loads” chapter provides guidance for designers and researchers to evaluate structures under fire for stability, both at the member (beam, column, and connection), and at the system levels. For example, at the member level, stability is typically addressed by limiting the cross-section’s element (flange or web) width to thickness ratio, or slenderness, so only member buckling occurs. Slenderness limits of structural steel sections depend on the ratio (E/fy)0.5 to determine whether elastic or inelastic buckling controls the behavior (design) of a member. However, as members are heated, the modulus of elasticity E and the yield strength fy are reduced at different rates, which in effect, could result in slender elements at elevated temperatures.
This work is of national and international interest and is targeted for both; practicing, and research structural engineers. The paper and presentation will provide the audience with an overview of the “Stability under Fire Loads” chapter in the upcoming edition of the SSRC Guide and demonstrate how practicing engineers can use this information to implement performance-based design of structures for fire loading.