Determining the Reliability of A Seismically Assessed Building Conclusion Using A Modified FEMA P-154 Procedure

Abstract

The quality of seismic risk management decisions depends on professional judgements. Such require an assessment of the reliability of the thought process and information used to give them credibility. The goal is to develop a process that assesses the reliability of a traditional P-154 assessment to determine whether it is sufficiently reliable to warrant action. P-154 is a triage approach meant to determine whether a detailed engineering assessment is required or not. Modifications to the P-154 procedures are proposed to warrant such actions without additional engineering assessment. This involves requiring highly experienced evaluators, specification of building document review, and technically independent supervision. Based on the nature of the conclusions, whether using the modifications or not, the reliability of the assessment can be evaluated, and a decision made whether it warrants action. It was validated by application to 56 likely hazardous buildings on three CSU campuses. The result of application of P-154 was that 52 of the 54 buildings need further engineering evaluation to reach a decision: two needed immediate attention, 12 requiring work overtime, where the reliability of all the evaluations indicated a good reliability for the conclusions, when the companion paper’s procedures for portfolio management were implemented. The application of the recommended approach was about $2,500 per building, including assessor time, travel, and expenses, more than the conventional P-154 cost but far less than the engineering P-154 assessment. A companion paper, Setting the Priority for Seismic Retrofit of Buildings Using a Modified FEMA P-154 [1] Procedure develops the seismic management program using this reliability determination as a key ingredient. The principal impact of the Modified P-154 process is that the retrofit decisions it recommended had acceptable reliability to CSU management and their advisors.