Coupling effects of the fragment impact and adjacent pool-fire on the thermal buckling of a fixed-roof tank

The combined loadings of the fragment impact and pool-fire caused by domino accidents in storage tank farms or oil depots can result in damage greater than that caused by a separate loading. However, due to the complexity of the combined loadings, these have not been well understood. In this study, the coupling effects of the fragment impact and adjacent pool-fire on the thermal buckling of a fixed-roof tank were numerically investigated. The effects of impact velocities, impact angles and fragment shapes on the failure mode and fire resistance of a fixed-roof tank were discussed. The results indicate that the coupling effects of the fragment impact and adjacent pool-fire were deeply different from those in which the fixed-roof tank was subjected to either fragment impact or adjacent pool-fire individually. The fire resistance and critical buckling temperature decreased for pre-damaged tanks comparing with no-pre-damaged tanks. Besides, the local buckling mode triggered by the adjacent pool-fire was depended on the impact dent zone caused by the fragment impact. Moreover, the fire resistance and critical buckling temperature reduced with the increase of the impact velocity, structural stability of the fragment and the decrease of the impact angle. This study can be used to understand the vulnerability and obtain the critical failure criterion of the large storage tanks under the coupling effects of multiple accidents, and optimize the steel structure design of oil tanks for resisting projectiles and pool-fires in tank farms to reduce the possibility of storage tank accidents.