# Post-Earthquake Fire Resistance in Structures: A Review of Current Research and Future Directions
## 8 Performance-Based Design for PEF  
Performance-based design is a critical component of structural engineering, especially in regions susceptible to earthquakes, where post-earthquake fires (PEFs) pose a substantial threat. This approach aims to ensure that buildings can withstand both seismic events and subsequent fires, achieving specific performance objectives that prioritize occupant safety and structural integrity [15]. In contrast to traditional design methods, which may inadequately consider the combined effects of earthquakes and fires, performance-based design provides a more holistic framework for assessing and mitigating risks [75]. The philosophy behind performance-based seismic design focuses on engineering structural elements to meet various performance levels, such as Operational (O), Immediate Occupancy (IO), LifeSafety (LS), and Collapse Prevention (CP), depending on the building's occupancy and importance [68]. For instance, buildings designed to the LS level--like certain residential and educational structures--should maintain stability sufficient for safe evacuation during a design-level earthquake, even if significant damage occurs [66]. Performance-based fire design primarily aims to contain fires within compartments, preventing their spread to other building areas. This is achieved through active measures, such as sprinkler systems, and passive measures, such as using non-combustible materials. The key objective is to ensure building stability for a sufficient duration, allowing for occupant evacuation and fire suppression efforts, even after earthquake damage. This duration, known as fire resistance, is typically expressed in minutes and is influenced by factors such as compartment size, opening dimensions, and specific fire scenarios [66]. One of the key challenges in performance-based design for PEF scenarios is accounting for the complex interaction between seismic and fire loads. Earthquakes can inflict damage that significantly reduces a building's fire resistance by compromising the integrity of fire-resistant components or impairing the functionality of active fire protection systems [48]. Thus, a comprehensive approach requires consideration of the following:  
* Potential damage to fire protection systems: Earthquakes can damage water supply lines, rendering sprinkler systems ineffective. Additionally, damage to passive fire protection, such as fire-resistant coatings on structural components, can expose these elements directly to flames, thereby reducing their fire resistance [72]. * Degradation of structural fire resistance: Earthquake-induced damage, such as concrete spalling or steel yielding, can significantly diminish the fire resistance of structural elements. Residual deformations from the earthquake can further exacerbate this degradation [65; 66]. * Changes in fire dynamics: Earthquake damage can alter fire spread patterns within a building. For example, the collapse of a floor can facilitate vertical fire spread, while damage to partitions can create openings that allow for faster propagation of fire and smoke [66; 75]. To address these complexities, a sequential analysis approach is commonly employed in performance-based PEF design, which involves the following elements:  
1. Applying gravity loads: Simulating the dead and live loads the structure typically supports under normal conditions [69; 75]. 2. Simulating earthquake loading: Using techniques such as pushover analysis, which subjects the structure to incrementally increasing lateral loads to simulate seismic effects and assess damage levels. The target displacement for this analysis is determined based on the desired performance level, such as LS, as outlined in guidelines like FEMA 356 [66]. 3. Applying fire loads: After simulating the earthquake, fire loads--often modeled using standard fire curves like ISO 834 [97] or natural fire models [69]--are applied to the damaged structure. This step determines the time to failure, known as fire resistance, while accounting for the impact of earthquake-induced damage.