Challenges and alternative approaches for simulating the response of steel structures exposed to fire

Abstract

Although structurally significant building fires are rare events, their occurrence can cause substantial damage and may lead to partial or complete system collapse. While fireproofing has proven to be effective in mitigating the effect of severe fires, it is rated for only a certain time and will eventually fail to provide adequate protection during a large or extended fire event. Furthermore, fireproofing typically is rated using a standard fire exposure, such as ISO 834 or ASTM E119, neither of which represent realistic fire exposures in an actual building. With the worldwide move toward performance-based fire protection engineering, understanding and quantifying system behavior through advanced numerical simulations, especially during the heating and cooling phases of realistic fire exposures, is essential for establishing proper performance-based provisions for fire engineering that ensure both safe and economical design. This paper highlights current challenges in simulating the effect of fire on steel components and frames, including proper representation of loading and boundary conditions, geometrical nonlinearities, material inelasticity, and numerical instabilities. The structural models considered include 2-D line elements, 3-D continuum elements, and multi-resolution models. In addition, the advantages and drawbacks of these models are highlighted and the implication of their features is discussed. The highlighted modeling approaches and the corresponding results shown can be used by engineers for selecting the most economical and effective techniques for simulating the response of components and structural systems to scenario fire hazards accurately. KEY WORDSFire, finite element analysis, steel structural buildings, reduced beam section connections.