A Textbook Case: Wind Failure of an Insulated Tank on Alaska’s North Slope and Review of Recent Changes to ASCE 7

In 2015, the author responded to the failure of a 3.4-million-gallon, insulated steel water tank in a remote village on Alaska’s North Slope. A significant windstorm had caused the outer layer of standing seam metal roofing to tear free of the tank, but wind speed estimates for the event were still well below expected design levels for the area, raising questions about the root cause of the failure. This paper will review the procedure and findings of the root cause investigation, including the meteorological study, failure analysis of welded connections and other components of the cladding system, structural analysis, review of the original design documents, and the challenges of conducting the field evaluation in winter conditions. Then, the authors will review past and current standards for the design of such tanks and cladding systems (both domestic and international), their role in the observed failure, and whether recent changes made to ASCE 7 starting in 2016 would have been sufficient to avoid this failure had they been in place when the tank was originally designed.