FPE Seminar Series: Strategies for Mitigating Fire Hazard in Steel Bridges
Speaker: Venkatesh Kodur, Professor and Chair of Civil Engineering @ Michigan State University
Title: Strategies for Mitigating Fire Hazard in Steel Bridges
Fire is one of the most severe environmental hazards to which the built infrastructure may be subjected during its lifetime. In recent years, due to rapid development of urban ground-transportation systems, as well as increasing transportation of hazardous materials, bridge fires have become a growing concern. Bridge fires can lead to significant economic and public losses; however, no specific fire resistance provisions are specified for bridges in AASHTO, NFPA, and other international standards. This is contrary to structural members in buildings where adequate fire resistance provisions are to be provided to maintain structural stability and integrity in the event of a fire.
To develop a comprehensive understanding on fire performance of steel bridges, experimental and numerical studies were carried out as part of a major collaborate research project. Data on existing bridges is utilized to develop an importance factor for assessing risk associated with fire induced structural collapse in a bridge. A number of fire tests on bridge girders was carried out to evaluate their fire behavior. Data from these fire tests is utilized to validate numerical models for tracing the response of steel bridge girders subjected to combined loading and fire conditions. Results from experimental and numerical studies indicate that typical steel girders in a bridge can experience failure under fire conditions in about 30-35 minutes. The time to failure and mode of failure in fire exposed steel girders is highly influenced by web slenderness, spacing of stiffeners, and type of fire exposure.
In the presentation, an approach, in the form of importance factor will be proposed for classification of bridges based on fire risk. Detailed results from fire resistance experiments and numerical studies carried out to evaluate fire resistance of steel bridges will be presented. A series of design strategies to enhance fire safety of critical bridges will be presented. These strategies range from utilizing inherent fire resistance in structural members, through advanced analysis approaches, to providing some level of fire protection (insulation) to vulnerable components of steel bridges. Applicability of proposed strategies to practical situations will be demonstrated through case studies on different steel bridges that experienced fires in recent years.
Venkatesh Kodur is a University Distinguished Professor in the Department of Civil and Environmental Engineering at Michigan State University. He also serves as Director of the Centre on Structural Fire Engineering and Diagnostics at Michigan State University. His research interests include: Evaluation of fire resistance of structural systems through large scale fire experiments and numerical modeling and Characterization of materials under high temperature. His research contributions has lead to the development of fundamental understanding on the fire behavior of material and structural systems and also resulted in numerous design approaches and innovative and cost-effective solutions for enhancing fire-resistance of structural systems. He has published over 425 peer-reviewed papers in journals and conferences, and has given numerous invited key-note presentations. He is one of the highly cited authors in Civil Engineering and as per Google Scholar, he has more than 9000+ citations with an "h” index of 53. The methodologies, techniques and design guidelines, resulting from his research, have been incorporated in to various codes and standards, as well practical applications, in the US and around the world