Mechanisms of Seismically Induced Settlement of Buildings with Shallow Foundations on Liquefiable Soil (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.
Influence of bearing pressure on liquefaction-induced settlement of shallow foundations
Géotechnique, 2013
Earthquake-induced soil liquefaction continues to pose problems for structures on shallow foundations. One particular problem is the excessive settlement that such structures undergo as a consequence of earthquake shaking. For design and insurance purposes it is therefore necessary to be able to estimate the magnitude of these settlements. Current procedures relate the potential settlement to foundation size and liquefiable depth. However, the influence of foundation bearing pressure is also a significant factor. In particular, experimental results have indicated that large bearing pressures may inhibit liquefaction underneath a shallow foundation, resulting in lower induced settlement. By collecting new data from 23 buildings that suffered settlement and tilting as a consequence of soil liquefaction during the 27 February 2010 Maule earthquake in Chile, the existing method of estimating liquefaction-induced settlement is reassessed and shown to require bearing pressure information....
Soil-foundation modelling for vulnerability assessment of buildings in liquefied soils
2020
Recent events have demonstrated that earthquake-induced liquefaction can result in significant structural damage and human casualties. The consideration of soil liquefaction has primarily been the domain of geotechnical engineering; however, recent studies have shown a strong interaction between liquefaction-development and the superstructure loads. Not only does liquefaction lead to a change in the shaking demands on the superstructure, it also changes the flexibility of the soil-foundation-structure system. Meanwhile, the high static shear forces from the foundation loads can result in a reduction or increase in pore pressure development. This strong soil-liquefaction-foundation-structure interaction (SLFSI) is a challenge for both geotechnical and structural engineers. This paper develops an efficient numerical procedure for the vulnerability assessment of buildings with shallow foundations to the combined impacts of seismic shaking and liquefaction. The approach quantifies settl...