Kinematic response of vertical and batter pile groups in non‐linear soft soil

Abstract

This paper presents a comprehensive numerical study on kinematic response of vertical and batter pile groups in soft soil, where soil non-linearity, batter angle, pile spacing and excitation frequency are related to pile-cap displacements, rotations, maximum pile moments, shear forces and axial forces. The finite element model is constructed in OpenSees MP, and parallel computing is utilized for a better (faster) performance. Results reveal that soil non-linearity has a profound impact on the kinematic interaction. Increasing batter angle decreases horizontal displacements but increases rotations. Batter pile groups yield lower spectral accelerations compared to vertical pile groups. For high 𝑃𝐺𝐴, the spectral accelerations of the pile-cap may be lower compared to the spectral acceleration of the seismic input motion. Estimation using non-linear interaction factors conservatively estimates pile-cap displacements and rotations, while roughly captures the effects with respect to batter angle and frequency content within the specified framework.

Practical macro‐element for vertical and batter pile groups

“…The adopted soil model Pressure Independent Multi‐Yield is an elastic‐plastic, soil model suited for clay 54 . The reader is referred to Cemalovic et al 55 . for a detailed description of the soil material model, soil profile and meshing strategies.…”

“…The adopted soil model Pressure Independent Multi-Yield is an elastic-plastic, soil model suited for clay. 54 The reader is referred to Cemalovic et al 55 for a detailed description of the soil material model, soil profile and meshing strategies. The pile-soil interface is modelled using frictional contact elements based on the Mohr-Coulomb criterion, penalty constraints and an implicit-explicit solution scheme.…”

Nonlinear earthquake response of integral abutment bridges on vertical and batter piles: A practical approach

“…An important part of the SSI‐analysis is the assessment of foundation input motion (FIM). Cemalovic et al 47 . explored the feasibility of using nonlinear kinematic interactions factors to estimate FIM, but this approach was based on the results of comprehensive finite element analyses.…”

“…The nonlinear time domain solution is validated using a fully coupled, three-dimensional finite element model constructed in OpenSees MP 44,45 and STKO 46 as described by Cemalovic et al 20,47 It should be noted that the contact elements available in OpenSees MP produce in some cases rather noisy results for transient analyses. This may occur even for integration schemes with numerical damping such as the Hilber-Hughes-Taylor method.…”

“…The nodes corresponding to the plane cutting the mid-span are fixed in the vertical direction, but are free to rotate and translate in the horizontal direction. The three-dimensional finite element model is validated in Cemalovic et al 47 Furthermore, the superstructure in both models is represented using linear beam elements, which confines nonlinear behavior to the foundation and soil. Figures 3A-D compare the macro-element solution against OpenSees MP in terms of deck displacements and accelerations when the deck is subjected to a horizontal, harmonic load…”