Reliability-Based Risk Matrix for Evaluating Existing Structures—Format and Real-Life Case Studies

This chapter introduces a simplified reliability-based structural risk matrix designed to evaluate existing structures in Canada. The matrix addresses the shortcomings of the conventional member utilization approach, which often leads to unoptimized decision-making. The text begins with a critical review of the member utilization approach, highlighting its limitations in determining the need and prioritization of repairs. It then introduces the concept of the reliability-based risk matrix, which categorizes risk levels based on the likelihood of occurrence and the associated consequence. The matrix is presented in a decision matrix format, with risk levels color-coded for easy interpretation. The text also discusses the limitations of the current practice in assigning the likelihood category, which is often subjective and lacks direct correlation with structural analysis findings. To address these limitations, the authors propose an alternative approach that defines likelihood categories based on the structural reliability for the assessed limit state. The proposed ranges of the probability of exceedance for the likelihood categories are validated against the target reliability indexes used in calibrating the safety provisions for new designs in established codes. The text concludes with three real-life case studies where variants of the reliability-based risk assessment matrices were developed and utilized to assess several projects in the industrial, commercial, and marine sectors. These case studies demonstrate the practical application of the proposed approach in making informed decisions regarding the need and urgency of repair. The chapter provides a comprehensive overview of the advantages of the reliability-based risk matrix, including its adaptability to project-defined structural evaluation limits and system response-based structural evaluation. It also highlights the importance of considering the system effect in structural assessments, which can effectively be done using the proposed reliability-based risk matrix.