Behavior of pipe rack structures under blast loads

In this study, a hydrocode analysis was performed to evaluate the behavior of pipe rack structures under blast loads. The LS-DYNA program was used for the simulation, and the reliability of the numerical model was verified using existing experimental data for column members subjected to blast loads. Typical pipe rack structures were then selected, and steel and reinforced concrete (RC) pipe rack structures were designed to yield equivalent performances based on structural design standards. Assuming a vapor cloud explosion scenario that occurs mainly in plant facilities, the blast load was calculated using the multi-energy method. The blast load was applied to the pipe rack structures, and structural responses such as column displacement and damage level were evaluated. A pressure-impulse (P-I) diagram was derived to identify the overpressure and impulse levels that induce specific damage states in each structure. The steel pipe rack structure showed a maximum support rotation of 2.47°, indicating high damage, while the RC structure exhibited only 0.22°, indicating minor damage. Fragility analysis results demonstrated that, under equivalent blast scenarios, the RC pipe rack structure had significantly lower failure probabilities than the steel structure. These results highlight the superior blast resistance of RC pipe racks and support risk-informed design through probabilistic evaluation.