Visual Indicator-Based Thermal Inference (VITI) for Post-Fire Structural Assessment

Abstract

This research introduces Visual Indicator-Based Thermal Inference (VITI) methodology, a practical and cost-effective approach for preliminary visual assessment of fire-damaged structures. Existing post-incident assessment methods often face limitations, particularly in developing countries where advanced testing equipment may be limited or unavailable, and 
frequently fail to translate observed damage into quantitative temperature exposure data. The VITI methodology fills this gap by using systematic visual observation and material degradation analysis to infer the temperature exposure and structural implications. It comprises 
three key steps: structured evidence captures (photos/videos, indicator extraction), mapping these indicators to temperature bands based on material behaviour at elevated temperatures, 
synthesizing this information to bound zone-level temperatures and evaluate potential structural implications. The methodology applicability and reliability are shown through two case studies: an industrial Reinforced Concrete (RC) structure subjected to a dust explosion followed by fire, and a residential load-bearing masonry structure with RC elements damaged 
by fire. The VITI offers engineers and assessment teams a valuable tool for immediate, reliable, and cost-effective initial structural evaluation, especially for RC and load-bearing masonry 
structures which are dominant in developing regions. However, the method has inherent limitations including uncertainty in temperature estimation due to exposure duration, material variability, and ventilation effects, and it should be regarded as a preliminary screening tool that may require supplementary non-destructive or destructive testing for critical structural 
decisions.