State of the Art and Practice in the Assessment of Earthquake-Induced Soil Liquefaction and Its Consequences (2021) / Chapter Skim
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9 Performance-Based Evaluation and Design
9 Performance-Based Evaluation and Design
Pages 180-189
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From page 180... ...
Seismic performance-based evaluation and design usually involves the probabilistic descriptions of ground motions, system response, physical damage, and loss, including casualties, direct economic costs, and indirect economic costs from loss of functionality (see Figure 9.1)
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From page 181... ...
In performance-based earthquake engineering, explicit consideration of uncertainty is taken into account through probabilistic evaluations of liquefaction susceptibility, triggering, and consequences combined with a probabilistic evaluation of the ground motion hazard to produce estimates of liquefaction risks that are rational and consistent. This type of approach was used to great effect in the design of liquefaction mitigation measures for the TONEN tank farm complex in Tokyo, Japan, in the 1980s (see Box 9.1)
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From page 182... ...
An impervious slurry wall was built around the site, pumps were installed, and a continuous program of pumping and monitoring of groundwater levels was instituted. Although the 2011 Tohoku earthquake caused extensive liquefaction of reclaimed land around Tokyo Bay (Yasuda et al., 2012)
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From page 183... ...
Response hazard curves account for local seismicity (e.g., including all expected earthquake magnitudes at all potential source-to-site distances) ; uncertainty in ground motions given those magnitude and distance combinations; and uncertainties in prediction of liquefaction triggering and movement of soils as a consequence of liquefaction movements (e.g., settlement, lateral spreading)
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From page 184... ...
developed a probabilistic version of the lateral spreading relationship developed by Youd and colleagues (2002) and used it to compute displacement hazard curves for a generic site assumed to be located in 10 U.S.
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From page 185... ...
performed structural analyses to evaluate damage to reinforced concrete frame buildings from differential ground movements and developed fragility curves for damage limit states while considering uncertainties in input parameters. To isolate the effects of liquefaction, they used damage models to compare damage scenarios with and without groundfailure-induced damage at a liquefiable site, and they noted the need for improved characterization of the relationships between ground movement and structural damage.
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From page 186... ...
The response models accounted for uncertainty in liquefaction triggering, uncertainty in the residual strength of the liquefiable soil, and uncertainty in the lateral displacement prediction. They defined five discrete damage states (none, small, moderate, large, and collapse)
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From page 187... ...
Finite element analyses of the soil-foundation-bridge system were used to predict system response related to nine response parameters, including peak pile curvature, maximum abutment seating displacement, and approach embankment settlement. Discrete damage states (e.g., cracking, yielding, and failure of piles)
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From page 188... ...
FIGURE 9.7 Illustration of life cycle costs for different soil improvement design options (Iai, 2008)
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From page 189... ...
Fully probabilistic procedures show that uncertainties, whether in prediction of liquefaction triggering or of consequences, significantly influence the calculated liquefaction hazards. Improved response models are required that better quantify uncertainty and allow better understanding of how much uncertainty can be reduced through such measures as increased subsurface exploration, increased field and laboratory testing, more sophisticated analyses, additional research, or other means.
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