Investigation of Cylindrical Steel Tank Damage at Wineries during Earthquakes: Lessons Learned and Mitigation Opportunities

Abstract

The moment magnitude scale (Mw) 6.0 South Napa earthquake caused damage to stainless steel cylindrical tanks used for wine storage and fermentation. The damage observed to the tanks included local buckling of the tank walls, anchorage failure, and damage at the top of the tanks as a result of the catwalk system. Inspections of these tanks after the South Napa earthquake provided the motivation and the basis for investigating the seismic behavior of stainless steel cylindrical tanks used for liquid storage. This investigation focused on (1) the behavior of stainless steel cylindrical tanks in previous earthquakes around the world, and (2) research performed to mitigate this damage. The damage to cylindrical steel tanks after the South Napa earthquake was found to be identical to damage documented by postearthquake reconnaissance reports from around the world. Large-scale experimental research (by other researchers) has already demonstrated the inadequacy of cylindrical tank anchorage details for the seismic risk at winery locations. Simplified elastic models developed by engineers are generally inadequate for predicting the level of stresses and seismic damage (such as local buckling) in cylindrical tanks. This paper summarizes the damage observed after earthquakes to cylindrical steel tanks used in the wine industry, and previous research performed to help mitigate the damage. The authors suggest avenues for future research and code regulation of these tanks to improve seismic performance and reduce the level of risk to wine owners.