Authors:T. Lipovics, S. Czakó, I. Kelemen, and A. Fischer
A newly developed technique is presented to estimate site specific seismic failure frequencies of several types of storage tanks. Seismic failure is a failure event triggered by an earthquake leading to material release and serious damages. The present method is based on the convolution of site specific seismic hazard curves and component dependent fragility curves. Fragility curves are calculated with the help of probit coefficients originated from the analysis of historical data of earthquake damage. The calculation considers only the filling level, pressure and the damage state of storage tanks, and neglects the shape, volume, material and other parameters. Determination of seismic failure frequencies for storage tanks is done for three different Hungarian plant sites (Paks, Püspökszilágy, Csömör) using seismic hazard curves. In contrast of the simplifications the obtained frequency values represent a conservative estimation of failure frequencies triggered by earthquakes, and in comparison to international failure data the calculated values indicate significant frequencies. Therefore, the results imply that despite of the moderate seismic activity in Hungary, the effects of earthquakes on major-accident hazards should be considered in quantitative risk assessment.