Probabilistic Modeling to Develop the Optimal Seismic Resilience Enhancement Strategy for Industrial Facilities

Industrial facilities play a critical role in economic continuity but are highly vulnerable to earthquake impacts due to their complex networks of interdependent components. This study proposes a probabilistic framework that integrates stochastic modeling and simulation-based optimization to evaluate the effectiveness of alternative seismic retrofit strategies. Unlike conventional buildings, industrial systems require specialized approaches that account for both direct repair costs and indirect losses such as production downtime. The framework incorporates models that capture component fragility, operational dependencies, and varying seismic intensities, enabling a comprehensive assessment of retrofit outcomes. Three retrofit strategies are examined: (1) revenue-based, prioritizing business continuity; (2) cost-based, minimizing structural repair costs; and (3) a hybrid approach. A benefit-cost analysis is conducted to determine the most efficient investment allocation. The framework is applied to three Iranian oil refineries with differing scales and seismic exposures. Results indicate that the revenue-based strategy often yields the highest benefit-cost ratio, especially in facilities with extensive downstream networks, while cost-based strategies may be more suitable when direct losses dominate. The findings emphasize the need for tailored, facility-specific retrofit planning that considers both structural and operational dimensions of seismic resilience.