FPE Seminar: A Risk-informed Framework for Evaluating the Structural Fire Safety of Buildings
Speaker: Shuna Ni, Assistant Professor, Department of Civil and Environmental Engineering, Utah State University
Title: A Risk-informed Framework for Evaluating the Structural Fire Safety of Buildings
Structural fire protection is a critical component of fire protection design. Structural fire damage can lead to severe loss of life as well as economic losses such as business disruption. The former requires that the structural fire protection of a building guarantees the life safety of its occupants and first responders during a fire; and the latter, that such protection provides the building with some level of resilience. Regardless of whether the goal is life safety or resilience, however, a framework for comprehensively assessing the fire risk to a building’s structure is indispensable. Previous studies have modified the PEER Performance-based Earthquake Engineering (PBEE) framework for structures on fire. However, they did not consider the multi-physics characteristics of fire damage, and estimated damage mainly based on simplified structural fire analysis and simplified damage classification. We, therefore, propose a probabilistic risk-informed framework that estimates direct fire loss based on explicit analysis of an entire building’s structural response to fire. Also adapted from the PEER PBEE framework, it comprises fire-hazard analysis, response analysis, damage analysis, and loss analysis. This framework takes account of uncertainties pertaining to the occurrence and growth of fires, as well as to buildings’ responses. As part of our transformation of this framework from an earthquake context to a fire context, we define fire-specific engineering demand parameters that are measurable and associated with the damage states of each component in a building. Our classification of damage states addresses gradual levels of repair efforts for those components, in addition to the collapse/no collapse criteria for an entire building. Then, based on this more realistic damage-state classification, we develop fragility functions and consequence functions. When coupled with probabilistic models for describing random variables, and advanced modeling techniques for structures on fire, this framework can output probabilistic risk information at both building-system and component levels. It provides a probabilistic methodology for the risk-informed performance-based design of buildings’ structural fire protection. The detailed risk-assessment results provided by this framework will also facilitate the analysis of a building’s recovery after a fire, which will help expand the scope of structural fire engineering beyond life safety to include resilience.
Dr. Shuna Ni is currently an Assistant Professor in the Department of Civil and Environmental Engineering at Utah State University. Her group’s overall goal is to increase built environments’ resistance and resilience to fires and fire-related multiple hazards, at both the single-structure and community levels, by bridging the gaps between fire protection engineering and civil engineering. At USU, Dr. Ni’s group carried out research on probabilistic structural fire engineering, with the ultimate goal to expand the scope of structural fire engineering beyond fire safety to include resilience. Her group also studies the fire safety of tall mass-timber buildings, impacts of fire on civil infrastructures, fire-related multiple hazards, and fire forensics.
Prior to this appointment, Dr. Ni worked in the Multi-Hazard Resilient Structures Group at Johns Hopkins University as a Postdoctoral Fellow. Her main achievements during the postdoctoral research include a methodology for the probabilistic fire loss estimation in reinforced concrete (RC) buildings, probabilistic material models for elevated temperatures, and efficient techniques for modeling the structural behavior of RC buildings under fire. Dr. Ni also studied the fire-safety issues particular to tall wood buildings and developed a numerical modeling procedure for analyzing the post-fire residual lateral resistance of cold-formed steel shear walls; the latter is in collaboration with the National Institute of Standards and Technology. Her research results have been incorporated into commercial software, disseminated in peer-reviewed journals, and presented at national and international conferences.
Dr. Ni received a bachelor’s degree in Civil Engineering from the Central South University, Changsha, China, in 2009, a master’s degree in Structural Engineering from Tongji University, Shanghai, China, in 2013, and then a doctorate degree in Civil Engineering from Texas A&M University, College Station, Texas in 2018, with an emphasis in Structural Engineering. The results of her doctoral studies have advanced the knowledge of structures under sequential fire-earthquake loads and provided the engineering community with predictive methods for assessing the potential damage to structures from such hazards.