Report No.: CCEER-07-7
Title: Strain Wedge Model Computer Program for Piles and Large Diameter Shafts with LRFD Procedure
Authors: Mohamed Ashour and Gary Norris
Date: October 2007
Sponsoring Agency: Nevada Department of Transportation (NDOT)
Department of Civil Engineering/258
University of Nevada, Reno
Reno, NV 89557
Based on the Strain Wedge (SW) Model Analysis, the computer program SWM6.2 allows the assessment of:
Lateral/axial response of isolated (single) pile and large diameter shaft, i.e. pile/shaft classification (short, intermediate or long) based on soil and pile properties; pile head lateral load-deflection behavior; lateral response of the isolated pile that includes (lateral deflection, bending moment, shear force and soil reaction) at particular values of pile head lateral load; excess pore water distribution along a single pile in liquefied soil; effect of lateral soil spreading on the pile response; p-y curves at different points on the isolated pile (max. 5 curves per run); t-z curve for each soil layer along the pile length; pile lateral, axial and rotational (spring) stiffnesses; axial response of the pile (load-settlement curve); skin and tip axial resistance of the pile; moment-curvature relationship for the pile/shaft cross section(s); moment-pile bending stiffness (EI) relationship for the pile/shaft cross section(s); curvature-pile bending stiffness (EI) relationship for the pile/shaft cross section(s); and linear and nonlinear modeling for pile/shaft materials.
Lateral response of pile/shaft group, i.e. advantage of using the LRFD procedure in the analysis; lateral resistance of a pile group with or without pile cap; pile head lateral load-deflection behavior for different individual piles in the pile group; lateral response (lateral deflection, bending moment, shear force and soil-pile reaction) for individual piles in the pile group; pile group lateral, axial and rotational (spring) stiffnesses (with/without pile cap); excess pore water distribution along individual piles in the group in liquefied soil; effect of lateral soil spreading induced by soil liquefaction on the pile group response; and lateral resistance of average pile in a group compared to a similar isolated pile
The program accounts for a pile/shaft of varying diameter, bending stiffness (EI) and type (short, intermediate or long). The linear and nonlinear behavior of pile/shaft material is part of the program analysis options. Linear behavior represents a fixed value for the bending stiffness (EI) of the pile cross-section(s) which is the initial EI. Nonlinear behavior allows the EI of each pile section to vary with the level of loading based on the moment-curvature relationship.