RENTON TANKS WERE SEISMICALLY BRACED WITH FRICTION DAMPERS
By Dave Swanson, Reid Middleton
Structural engineers faced a retrofit challenge after two Renton-based elevated water tanks were damaged during the Nisqually earthquake. How can the necessary structural repairs be used to seismically upgrade these lifelines with minimal extra cost? And what earthquake engineering standards should be applied to these non-building structures?
Elevated water tanks are rare, and the most current seismic evaluation and retrofit guidelines focus on buildings, not on elevated towers that carry an unusually heavy top weight. What resulted was a careful extrapolation of building-related guidelines, which innovatively permitted performance-based engineering concepts to be applied to these non-building structures.