Analysis of Steel Tanks in Chile Subduction Earthquakes

Abstract eng:
Steel tanks have presented repeated failures during last large earthquakes, mainly buckling of shell, horizontal sliding and some collapses, despite being designed with codes widely used in the world such as the standards API 650-E, AWWA D100, NZSEE and Chilean NCh2369.Of2003, causing significant losses in the production of heavy industry, especially for burning generation after the earthquake. This unwanted performance was confirmed again to analyze a large number of tanks located in epicentral subduction zones of Chile, most of these cases studied were designed with the code API 650-E, confirming that it is necessary to modify the design codes to limit frequent failures, since there is no consistency with the observed, despite permanent evolution of design codes. The high seismicity of Chile as well as the large magnitude of their recent subduction earthquakes has allowed to measure instrumentally new effects on the design of steel tanks that may contribute to observed failures. In this study, the backward analysis of the performance of tanks for the following Chilean earthquakes is considered: Central Chile, 1985, Tocopilla, 2007, Maule 2010 and Illapel 2015. In the Chilean Earthquakes Maule 2010 and Illapel 2015, important coseismic horizontal GPS displacements were measure at the coast, showing that is the characteristic of the interplate subduction large earthquakes. This horizontal displacement may produce horizontal sliding of tanks in the direction perpendicular to the coast on the convergence of the subducted plate. To avoid horizontal sliding of the tanks due to these coseismic displacements of the self-anchored solution for the tanks is proposed. Anchored tanks during the Chilean earthquakes showed good performances. In the most recent Illapel earthquake Mw=8.4 of September 26, 2015, the network of wide band accelerograph measured important displacement in the relative displacement spectrum in the range of 10 to 15 sec. Since the sloshing period of tanks is in this period range, the effects on the different sloshing formulas is analyzed. The characteristics of the soils foundation are also considered, since determine seismic response of steel tanks. Finally, the review of anchored and self-anchored cylindrical tanks and main fails after these large earthquakes, which were located in epicenter subduction zones near of Nazca plate asperities, with available design information to perform "Backward Seismic Analysis" is considered.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket