Inelastic Seismic Response of Bridge Drilled-Shaft RC Pile/Columns

Abstract

An analytical model based on a Winkler beam is used to represent the lateral force response of a reinforced concrete (RC) pile in cohesionless soil. An inelastic finite-element analysis was performed on the structure, using as the pile constitutive model the section moment-curvature relationship based on confined stress-strain relationships for the concrete. Parameters varied were pile head restraint (free and fixed head), height of pile head above grade level, and soil stiffness. Linear, bilinear, and hyperbolic soil models were examined. The analysis showed that shear would be significantly underpredicted by an elastic analysis, as inelastic behavior moved the point of maximum moment in the pile shaft closer to the surface, thus reducing the shear span. Maximum moment depth in the pile shaft and plastic hinge length were also shown to be strongly dependent on soil stiffness, and in the case of fixed-head piles, on abovegrade height of the superstructure. Linear soil models were shown to be adequate for most cases of pile/column design.