Seismic Vulnerability Study of Derrick Supported Flare Using Incremental Dynamic Analysis

The vulnerability of industrial plants to natural hazards has made world worries because of countries general disability about the prediction of the level of effects and preparedness for the consequences of these types of events. For this purpose, seismic assessment of plant equipment is a strategic issue. One of the most equipment that is used in most oil & gas plants is stack flares. Stack flares are a type of stacks that are used for burning additional flammable gases before causing any other problem for other plant facilities. Proper seismic assessment of this type of equipment has been missed in the past and its exact performance evaluation can be effective in determining probable damages in future earthquakes and distinguishing the weakness of components of this type of structure. In this study probabilistic seismic behavior of two designed and constructed stack flares are investigated and using incremental dynamic analysis their fragility curve and behavior factor are calculated. Results show that in ordinary intensities, the seismic demand of these structures is not considerable but in range of rare intensities, extreme damages are probable. Also, in the above case studies, the performance of 4 side stack with respect to 3 side stack was more proper, and seems more assessment is needed on the suggested behavior factor by codes.