Seismic Risk Assessment of an Existing Petrochemical Structure Retrofitted with Base Isolation System

Petrochemical plants located in seismic zone areas are at risk of experiencing damage to their equipment and in the most severe cases, potential harm to human lives. In some cases, after a strong earthquake, it might be required to initiate a temporary shutdown to plan the necessary repairs and replacements of damaged components to restore the standard safety level. The implementation of a base isolation system as a common passive control seismic protection technique can effectively mitigate the risk of damage to the structure by minimizing the ground-transferred energy induced by earthquakes to the superstructure. This paper focuses on conducting a seismic assessment of a typical steel petrochemical plant retrofitted with base isolation system. The study employs probabilistic approaches to estimate the probability of failure at different damage levels and also considers soil-structure interaction, to provide more realistic predictions of the seismic performance. Fragility curves are generated according to the response of the structure to earthquake strong motions. The results demonstrate that employing base isolation in existing petrochemical plants significantly reduces structural damage occurrence. This study is useful in designing and implementing protection and rehabilitation strategies to prevent and control further damage.