Date of this Version



earthquake reconnaissance, unreinforced masonry, cylindrical tanks


Civil Engineering | Structural Engineering


Structural damage was observed during reconnaissance after the 2014 South Napa Earthquake, and included damage to wine storage and fermentation tanks, collapse of wine storage barrel racks, unreinforced masonry building partial or full collapse, and residential building damage. This type of damage is not unique to the South Napa Earthquake, and was observed after other earthquakes such as the 1977 San Juan Earthquake, and the 2010 Maule Earthquake. Previous research and earthquakes have demonstrated the seismic performance of cylindrical fluid-filled tanks is controlled by both the tank and the sloshing motion of the liquid inside. Unlike building structures, steel tanks do not have the means to dissipate energy through buckling of members. Analysis of the tanks to determine overturning moments must incorporate inelastic deformations. Observed damage of cylindrical steel tanks has been documented back to the 1977 San Juan Earthquake and includes anchorage failure and buckling of the tank walls. More recently, this type of damage was observed during the 2014 South Napa Earthquake at vineyards. API 650 and AWWA D-100 provide guidelines and limitations for engineers to design cylindrical fluid filled tanks for the oil and water industries respectively. The consistent damage to steel tanks in the wine industry suggests a similar standard should be applied.