# Post-Earthquake Fire Resistance in Structures: A Review of Current Research and Future Directions
## 8 Performance-Based Design for PEF
### Factors Influencing PEF Performance and Damage Assessment  
Several factors influence the performance and damage assessment of reinforced concrete (RC) and steel structures during post-earthquake fires (PEF):  
* Geometric Damage Parameters: Concrete cracking, spalling, and residual deformation significantly impact the thermal performance of RC columns under PEF conditions [13]. Among these, concrete spalling is the most critical factor, followed by cracks, while residual deformation has the least impact [61]. As the depth of spalling and interlayer displacement angle increase, residual deformation also increases, leading to a reduction in fire resistance [36]. Cracks and spalling contribute to a non-uniform axial thermal field distribution within the column [61].
* Mechanical Parameters: Axial compression ratio, reinforcement ratio, and eccentricity are key mechanical parameters affecting the fire resistance of damaged RC columns. The axial compression ratio is particularly influential, significantly impacting both the fire resistance and load-bearing capacity of RC columns subjected to PEF; therefore, it should be meticulously controlled. Eccentricity alters the axial pressure on a damaged column, causing it to become biased, which negatively affects its fire resistance. In contrast, the reinforcement ratio has a negligible effect on the fire resistance of PEF-damaged columns [61].
* Performance Levels: Structures designed for varying performance levels, such as Immediate Occupancy (IO) and Life Safety (LS), exhibit different degrees of damage under PEF conditions. For instance, at the IO level, minor damage occurs with no significant impact on PEF resistance. However, at the LS level, extensive damage in beams and ductile columns can lead to spalling of the concrete cover, compromising fire resistance [16; 66].
* Fire Scenarios: The extent of fire spread and its duration play a critical role in determining PEF performance [101]. In steel moment-resisting frames, the location and extent of the fire can affect the failure mode and the time the structure can withstand fire [71]. Fire scenarios considering simultaneous fire onset, as well as delays of 5 min and 25 min in a multi-story steel frame, result in varying fire resistance durations [75].  
* Stiffeners and Connections: The presence and type of stiffeners and connections are crucial in determining PEF performance. In steel structures, internal ring stiffeners significantly enhance the fire resistance of tubular T-joints under PEF conditions. The degree of damage greatly influences the fire resistance of both stiffened and untiffened T-joints [79]. In gusset plate moment connections (GPMC), the presence of stiffeners and the magnitude of vertical load significantly affect connection performance during PEF [98].
* Material Properties: The degradation of material properties in both concrete and steel at elevated temperatures critically impacts overall structural behavior. The thermal properties of concrete and rebar are essential considerations when analyzing PEF in RC structures [65].  
It is important to note that these factors are interrelated, and their combined effects determine the overall PEF performance and damage assessment of a structure. Further research is essential to fully understand these interdependencies and to develop accurate predictive models for assessing PEF performance.