Engineering Structures

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1 1 Engineering Structures Volume 56, November 2013, Pages Performance of stainless steel winery tanks during the 02/27/2010 Maule Earthquake Erick González, José Almazán, Juan Beltrán,Ricardo Herrera Pontificia Universidad Católica de Chile, Chile Universidad de Chile, Chile This document intends to be the basis for new seismic design and construction recommendations for wine production facilities. Highlights The Chilean wine industry was severely affected by the Maule Earthquake. According to preliminary estimates, losses reached approximately 125 million liters of wine (12.5% of production). The inspection found several design and detailing mistakes. Static non-linear finite element model was able to predict failures of legged tanks. Abstract The Maule Earthquake (February 27, 2010, Chile), one of the largest recorded in history, affected a large area of the country, where several important industries were located. The wine industry was particularly vulnerable, because most of the Chilean wine was produced in the affected area. With the support of the industry and the government, a large reconnaissance effort was undertaken. The inspection found several issues with the tanks and other elements used in the wine making process that resulted in large losses, including lack of structural seismic design and detailing, lack of redundancy, and inadequate anchorage design and execution. A summary of the major findings of this inspection are presented, followed by a comparison of the results of a linear and nonlinear finite element models of one case of the tank typology most damaged by the earthquake, namely a leg-supported tank, with the observed performance. The finite element models were able to predict the location of stress and strains concentrations and the type of damage that led to the failure of the structures represented by the models. Additionally, the capacity obtained from the models compared favorably with the capacity obtained using an approximate design method proposed by other researchers. These results could be used to develop seismic design and construction guidelines to lower the vulnerability of the wine industry in future earthquakes.

2 2 Key words: Maule Earthquake 2010; Wine storage systems; Buckling failure mode; Seismic design codes; Stainless steel thin walled tanks; Anchorage failure;reconnaissance work; Seismic vulnerability; Industrial facilities Fig. 1. Rupture zone, affected area, and recorded PGA. Fig. 2. Response spectra of recorded ground motions and design spectra from NCh2369.Of2003, for 2% equivalent viscous damping, and soil type III. Fig. 3. Connection between bottom course and tank bottom: (a) Pass-through course; and (b) butt welded bottom course and reinforcing ring.

3 3 Fig. 4. Diamond shaped buckling mode of failure: (a, b) FBSST-11 and FBSST-23 with radial stoppers; (c) FBSST-25 with L shape anchors; and (d) second course failure. Fig. 5. Elephant foot buckling mode of failure: (a c) FBSST-21; and (d) FBSST-27. Fig. 6. Failure of the anchorage system: (a) FBSST-17; (b) 200 m 3 FBSS tank; (c) FBSST-15; and (d) FBSST-25. Fig. 7. Damage caused by sliding and overturning and subsequent impact of tanks: (a) overturned tank (FBSST-16); and (b, c) impacted tanks (FBSST-26, FBSST-13). Fig. 8. Collapse of tanks due to suction: (a) buckling at the roof (FBSST-11); and (b) overall failure (FBSST-23).

4 4 Fig. 9. Scheme of a typical LSSS tank. Fig. 10. Typical buckling failures in LSSS tanks: (a) acceptable buckling in the top of leg (50 m 3, leg plate thickness m); (b) unacceptable buckling in the top of leg (15 m 3, leg plate thickness m); (c) chain collapse caused by buckling in the top of leg (20 m 3, leg plate thickness m); and (d) unacceptable buckling in the bottom of central leg (50 m 3, leg plate thickness m). Fig. 11. Typical strong leg-weak wall failure in small tanks without stiffening system at the bottom: (a) 15 m 3 LSSS tank; and (b) 10 m 3 LSSS tanks. Fig. 12. Failures of the height-adjustment devices: (a) lateral deformation of the leveling screw; and (b) lateral deformation of the leveling screw and collapse of the leg. Fig. 13. Performance of anchorage systems: (a, b) bolt pull-out; and (c) undamaged anchorages.

5 5 Fig. 14. Suction damage: (a) roof deformation; and (b) tank collapse. Fig. 15. Effects of displacement of unanchored LSSS tanks: (a) leg displaced about 200 mm; and (b) tanks overturned after falling into a gutter. Fig. 16. Stress strain curves from testing programme and average stress strain curve. Fig. 17. Schematic view of the ANSYS 3D linear model. Fig. 18. Distribution of the von Mises stress for the model subjected to NCh2369 Design Spectrum: (a) tank wall stresses; and (b) support structure stresses.

6 6 Fig. 19. Distribution of the von Mises stress for the model subjected to Curicó Response Spectrum: (a) tank wall stresses; and (b) support structure stresses. Fig. 20. Non-linear finite element model of the leg-supported tank considered. Fig. 21. Leg flat zone and leg corner zone stress strain curves. Fig. 22. Displacement control analysis of the tank leg.

7 7 Fig. 23. Capacity curves: (a) axial load P = Po; and (b) axial load P = 2Po. Fig. 24. von Mises stress distribution (in Pa) in the tank leg subjected to lateral displacement in X- direction (radial), and axial load P = 2Po: (a) at maximum shear load Vp = 0.91 Po; and (b) at minimum post-peak shear load Vmin = 0.64 Po. Fig. 25. Capacity-demand diagrams: (a) axial load P = Po; and (b) axial load P = 2Po. Table 1. Observed damage in FBSS tanks. Table 2. Summary of the results of the pushover analyses of the tank leg. Table 3. Summary of the results given by the design procedure proposed by Ashraf et al. [22].