Seismic fragility curves for stainless-steel wine storage tanks

Abstract

Wine storage tanks in seismically active parts of the world sustain significant earthquake-related damage with major financial loss implications. Consequently the development of fragility curves for such tanks using empirical damage data offers an opportunity to better understand real risk exposures and to plan for and mitigate earthquake related damage in the future. The seismic fragility curves can be used for running an earthquake scenario for other wine regions to estimate the probability of earthquake damage and further financial loss estimation. Fragility curves for wine storage tanks were developed utilising damage data collected from approximately 3400 tanks that were subjected to three major earthquakes in New Zealand in 2013 and 2016. Two-parameter (median and log-standard deviation) log-normal distribution variables were used to represent the fragility curves, and peak ground acceleration (PGA) was utilised to represent the intensity measure of the seismic ground motion. Damage states for Flat-Based (FB) and Legged (LG) wine tanks were introduced in accordance with the repair that was recommended by the structural engineers at the time of post-earthquake damage assessment of the affected wineries. A parametric study was also conducted, considering fragility curves for tanks with different capacities and different percentage of wine contents. Based on the analysis, complete damage of FB and LG wine tanks was forecast at median PGAs of 1.0 g and 0.88 g respectively in the 2013 and 2016 earthquakes, while the median PGA for minor damage to FB tanks was 0.18 g and the median PGA for minor damage to LG tanks was 0.23 g. The research presented herein highlighted the importance of evaluating and improving the seismic resilience of storage tanks within wineries located in seismicity active regions.