Inelastic pile behavior with and without liquefaction effects

Case histories reported, following earthquakes reveal that demands to reinforced concrete (RC) pile shafts during strong earthquakes may be significant enough to force plasticity locally in the member. Importantly, when these demands are below ground level and thus difficult to access post-earthquake, characterization of their location and extent should be a focus during design. This issue is investigated herein using nonlinear static pushover analyses of reinforced concrete piles embedded in layered soils with and without liquefaction. Using a soil-pile finite element model capturing both soil and pile nonlinearities, a numerical parametric study is undertaken, considering various pile diameters, above-ground heights, reinforcement ratios, and soil layering configurations. Pile behavior in these conditions is investigated and characterized via: (i) normalized plastic hinge length, (ii) normalized maximum moment location, and (iii) global (displacement) and local (curvature) ductility demands. Importantly, the plastic hinge length of piles extending through liquefiable layers is observed to be much larger than that of non-liquefiable conditions (on an average 1.4 times).

► Nonlinear static pushover analyses are performed for piles in different conditions.
► Pile inelastic property is characterized by plastic hinge length and ductility.
► The plastic hinge length of pile in liquefiable layer is higher (around 1.4 times).