Christopher R. McGann

Applicability of Conventional p-y Relations to the Analysis of Piles in Laterally Spreading Soil

This paper presents a kinematic analysis of a single pile embedded in a laterally spreading layered soil profile and discusses the relevancy of conventional analysis models to this load case. The research encompasses the creation of three-dimensional (3D) finite-element (FE) models using the OpenSees FE analysis platform. These models consider a single pile embedded in a layered soil continuum. Three reinforced concrete pile designs are considered. The piles are modeled using beam-column elements and fiber-section models. The soil continuum is modeled using brick elements and a Drucker-Prager constitutive model. The soil-pile interface is modeled using beam-solid contact elements. The FE models are used to evaluate the response of the soil-pile system to lateral spreading and two alternative lateral load cases. Through the computation of force density-displacement (p-y) curves representative of the soil response, the FE analysis (FEA) results are used to evaluate the adequacy of conventional p-y curve rel...

Simplified Procedure to Account for a Weaker Soil Layer in Lateral Load Analysis of Single Piles

AbstractThis paper presents a procedure to account for the presence of a weaker layer of soil in a beam on nonlinear Winkler foundation analysis of a laterally loaded pile or drilled shaft. Three-dimensional (3D) finite-element (FE) models, considering a single pile embedded in a soil continuum, are used to compute representative p-y curves for various combinations of soil profile and pile diameter. Comparisons between the p-y curves resulting from homogenous and layered soil profiles, in which a weak soil layer is located between two stronger layers, provide the means to identify reductions in the ultimate lateral resistance and initial stiffness of the p-y curves representing the stronger soil owing to the presence of the weak layer. These reductions are characterized in terms of an exponential decay model. Dimensionless parameters are proposed as a means of implementing appropriate reductions for an arbitrary soil profile and pile diameter. Validation of the reduction procedure is conducted through a c...

Numerical Assessment of Three-Dimensional Foundation Pinning Effects during Lateral Spreading at the Mataquito River Bridge

This paper presents a three-dimensional (3D) finite-element analysis of a bridge abutment and foundation system subjected to the kinematic demands of lateral spreading. The selected bridge system corresponds to the Mataquito River bridge in Chile. The 2010 Maule earthquake caused extensive lateral spreading on both river banks at this site. Observations suggest that 3D effects may have contributed to reducing the structural demands placed on the abutment and foundations during lateral spreading. Several 3D models representing the existing site geometry and a widened approach embankment are developed and used to estimate and compare bending demands in the shaft foundations supporting the bridge abutment. A simplified design method that accounts for pile pinning effects is also assessed as a possible tool to address this problem.

3D models of Quaternary-aged sedimentary successions within the Canterbury, New Zealand region

ABSTRACT A 3D high-resolution model of the Quaternary geological stratigraphic sequence in the Canterbury, New Zealand region is developed utilising datasets of over 500 high-quality water well logs from a database of 29,985, and over 370 near-surface cone penetration test (CPT) records from a database of 13,670. The model, developed using geostatistical Kriging, represents the complex interbedded regional Quaternary geology by characterising the boundaries between significant interbedded geological formations as 3D surfaces. The model is examined in the form of both geological surface contour maps and vertical cross sections, where the most evident trend identified is the easterly dip caused by the dominant alluvial deposition of terrestrial sediments. The developed 3D interbedded Quaternary stratigraphy model has several applications for hydrologic modelling, earthquake-induced ground motion simulations and seismic site characterisation. For the latter case, the role of the model in constraining surface wave analysis-based shear wave velocity profiling is illustrated.

Influence of Modeling Decisions on Three-Dimensional Finite Element Analysis of Two Existing Highway Bridges Subjected to Lateral Spreading

Three-dimensional finite element models are developed for the approaches of two Chilean bridges. A kinematic loading regime representative of postevent deformations associated with liquefaction-induced lateral spreading is used to analyze the models. Three important aspects of the modeling of this load case are assessed for such structures. First, the bridge deck and associated expansion gap and their effect on the overall response of the bridge–foundation–soil system are considered. The lateral resistance supplied by the bridge deck can play an important role in the general response of the model, and consideration of the expansion gap could lead to distinct pre- and postclosure deformation mechanisms. Second, elastic and elastoplastic constitutive responses in the deep foundations are explored, and the nonlinear nature of the drilled shafts is shown to be of essential importance. Finally, the effects of the inherent three-dimensional characteristics of each bridge are addressed. These effects are shown to play a significant role in the overall response of each bridge, which highlights the need for analytical procedures that consider three-dimensional effects.