ABSTRACT
Capped rigid piles may rotate forward and/or backward subjected to lateral spreading. The 2-layer model and solutions well capture the nonlinear response of the piles. The associated parameters [i.e., a movement factor α (= 1.39–1.5) and rotational stiffness of pile-cap connections] are deduced from ten model tests with diverse movement profiles under forward rotation. As for back-rotated piles, their response (deflection, rotation and bending moment) is amplified around a singularity stiffness. The 2-/3-layer models provide the expressions to estimate the stiffness, the amplification degree and the sliding depth at which the singularity occurs. The back-rotation stiffness of typical pile-cap connections is determined extensively using 1 g model tests. The models and expressions well capture the response of the 1 hg model piles, and the centrifuge test piles with P-Δ effect, and reveal new failure mechanism of Showa Bridge and safety state of the piles underpinning Christchurch bridges.
