An enhanced machine learning-based rapid visual screening framework for low-rise RC buildings considering model uncertainty and decision threshold optimization

Existing structures can become seismically vulnerable over time due to various factors including deterioration and outdated or seismic design provisions. Rapid visual screening (RVS) methods are commonly used to quickly filter large building inventories for at-risk structures, typically based on simple visual inspections, such as sidewalk surveys. In a previous study, the authors developed a machine learning (ML)-based RVS method for low-rise reinforced concrete (RC) buildings capable of identifying buildings that are likely to be severely damaged in an earthquake with an accuracy of 71%. However, uncertainty in the model’s predictions remains a concern. This study refines the previously proposed RVS methodology by addressing model uncertainty and minimizing misclassifications. Two primary approaches are proposed: the first analyzes class probabilities from the ML-based screening model to assess the prediction uncertainty rather than relying on the final predicted damage class. With this approach, buildings for which the ML model shows high uncertainty can be prioritized for more detailed evaluation. The second approach aims to optimize the decision threshold used by the ML model to more accurately identify buildings at risk of severe damage. This is done by evaluating the relative cost of misclassifications, low risk buildings identified as high risk (false positives) and high-risk buildings identified as low risk (false negatives). Building on the findings, this paper proposes a comprehensive three-level machine learning-based methodology for enhanced rapid seismic vulnerability assessments.