Centrifuge Experimentation of Building Performance on Liquefied Ground (original) (raw)
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The results of fully coupled, three-dimensional (3D), nonlinear finite-element analyses of structures founded on liquefiable soils are compared with centrifuge experiments. The goal is to provide insight into the numerical model's capabilities in predicting the key engineering demand parameters that control building performance on softened ground for a range of structures, soil profiles, and ground motions. Experimental and numerical observations will also guide future analyses and mitigation decisions. The numerical model captured excess pore pressures and accelerations, the dominant displacement mechanisms under the foundation, and therefore building's settlement, tilt, and interstory drift. Both experimental and numerical results showed that increasing the structure's contact pressure and height=width (H=B) ratio generally reduces net excess pore pressure ratios in soil but amplifies the structure's tilting tendencies and total drift. The settlement response of a structure with a greater pressure and H=B ratio was also more sensitive to soil-structure-interaction induced forces, which could at times amplify on a denser soil with less softening. A denser soil profile also increased building's flexural drift in all cases by reducing excess pore pressures and rocking drift, while amplifying foundation accelerations and total drift. Numerical simulations captured these trends well. These experimental and numerical results point to the importance of taking into account a building's dynamic properties and overall performance in mitigation design.
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Use of centrifuge modelling to improve lessons learned from earthquake case histories
2012
Current procedures relate potential liquefaction induced settlements to foundation size and liquefiable depth. However, the analysis of field case histories suggests that the influence of foundation bearing pressure may also be a significant factor influencing such phenomena. Data from 24 buildings that suffered settlement and tilting as a consequences of soil liquefaction during the February 27th 2010 Maule earthquake in Chile, are herein analyzed and compared with data from other earthquakes. Although case history data play a crucial role in geotechnical earthquake engineering, in many cases their analysis is limited to speculation therefore experimental verification is often required. Thanks to the significant development in dynamic geotechnical centrifuge modelling in the last 30 years, we are today able to carefully reproduce field motions enhancing the reliability of experimental results. This is the case for the centrifuge tests discussed in this paper, which have been the fi...
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