Nonlinear Soil-resistance (p-y) curves can be
internally generated by the program for the following
stiff clay with or without free water,
modified stiff clay without free water using initial k,
sand (Reese et al),
sand (API Criteria),
Piedmont residual soil,
cemented c-φ(silt) soil,
elastic subgrade and
API soft clay with user-defined J.
Internally-generated p-y curves may be printed
at any depth for reviews, reference or usage in other
Output text file from LPILE includes details with
all influencing parameters used for the computation of
internally-generated p-y curves. A narrow output
format can be selected so all the output tables fit within
a standard page width, which is convenient for project
documentation and reporting.
Users may optionally input their own lateral
load-transfer (p-y) curves for specified
soil layers. This is useful for sites with instrumented
load tests or where the geotechnical engineer provides a
specific variation from the traditional p-y
curves. LPILE includes a dynamic interface
where the user can see the shape of the inputted curve and
can also Paste values from Windows Clipboard (copied from
a spreadsheet) or read from a saved file.
LPILE automatically adjusts p-y curves
for soil-layering effects (for example, where there may be
layers of sand and clay). The layering-correction method
proposed by Georgiadis is automatically applied to the
internal p-y curves that are internally
generated by LPILE . Users can ask the program to
print out p-y curves at various depths of
interest and the output text file will include the
complete set of parameters used for the computation of
the p-y curves, including the resulting
modifications from Georgiadis (either in effective depth
or in average cohesion).
User-defined multipliers are provided to reduce (most
common) or increase (less likely) the soil resistance
(p-y) curves at any points along the length
of the pile. This feature may be used to account for
"Group" effects in closely-spaced piles or perhaps to
reduce the response of liquefied layers for sustained
long-term loading or for certain seismic
Internal modification factors are implemented to model
pile batter and sloping ground surfaces. LPILE
includes a dynamic interface where the user can see
graphically the geometry of the model and applied
A nonlinear resistance curve may be defined by the
user to model the additional tip shear resistance
provided by the soil at the base of large-diameter
drilled shafts and/or short piles. LPILE
includes a dynamic interface where the user can see the
shape of the inputted curve and can also Paste values
from Windows Clipboard (copied from a spreadsheet) or
read from a saved file.
LPILE has the capability of analyzing the
behavior of piles subjected to free-field soil movements
in the lateral direction. LPILE includes a
dynamic interface where the user can see the shape of
the inputted curve and can also Paste values from
Windows Clipboard (copied from a spreadsheet) or read
from a saved file.
The user may optionally ask the program to generate and
take into account nonlinear values of flexural stiffness
(EI). These values are generated internally by the
program based on the following:
cracked/uncracked concrete behavior,
user-specified pile dimensions, and
nonlinear material properties.
The interface for pile properties provides users with
a selection of predetermined pile sections with non linear
bending charateristics or elastic sections, with graphical
displays and tips.
Based on inputted pile properties, the program can
generate graphics of:
Flexural Stiffness (EI) versus Bending Moment (M)
Bending Moment (M) versus Curvature
Four values (K22, K23,
K32, and K33) of a typical 6x6 matrix
for foundation stiffness may be generated by the program for a
range of loading or deformation. These values can be used to
model nonlinear foundation springs in the analysis of the
A new feature allows users to generate terms of stiffness
matrix based on:
Computed maximum shear and bending moment
Computed maximum deflection and rotation
User specified deflection and rotation
Graphic plots are generated to see generated
components of the stiffness matrix with respect to pile-head
displacements and rotations and with respect to pile-head
forces and moments
The user may define up to 10 pile sections with nonlinear
bending properties. This allows a designer to see the effects
from say cutting off part of the reinforcing steel at the
lower sections of a drilled shaft.
LPILE has the capability to perform push-over
analyses and can study the pile behavior after the
development of plastic hinges (yielding). New control
features have been added for Pushover Analyses and users
can see output plots of Shear vs Pushover Deflection and
Bending Moment vs Pushover Deflection.
Bundled bar arrangements can be modeled in
LPILE for 2-bar and 3-bar bundles.
The reinforcing steel of a pile section can be offset
from the centroid. This option was provided to allow
analysis of drilled shafts where the reinforcement was
placed (or accidentally moved) off-center.
Boundary conditions and loading
(Features for Non-LRFD Analyses)
Five sets of boundary conditions are available to model
the pile head:
pinned head with sway,
fixed head with sway,
elastically-restrained without sway, or
elastically-restrained with sway.
Depending on the boundary conditions, pile-head loading may be applied as:
specified lateral displacement, or
specified pile-head rotation.
Up to 50 different load cases may be applied at the pile
head in a single analytical run. This is a helpful feature
for the quick observation of pile behavior for a specified
range of external loads: Shear vs Pile-Head Deflection and
Maximum Bending Moment vs Pile-Head Shear.
Users can specify any of the applied loads to be used for
computations of pile-head deflection vs pile penetration
to check critical pile length and produce efficient
A set of distributed lateral loading may be specified and
may be applied anywhere along the length of the
pile. Distributed loading may be constant or may vary
linearly with depth. LPILE includes a dynamic interface
where the user can see the shape of the inputted curve and
can also Paste values from Windows Clipboard (copied from a
Multiple profiles of distributed loading and/or soil
movement may be entered in LPILE (one for each load
(Features for LRFD Analyses)
LPILE has the capability of performing analyses
for Load and Resistance Factor Design (LRFD).
Up to fifty load-case combinations may be defined with
up to 100 unfactored loads grouped in 13 pre-defined load
Load-case combinations are defined by entering the load
factors for each load type and the resistance factors for
both flexure and shear. Optionally, the user may enter the
load case combinations by reading external text files
(previously created by the user).
Unfactored loads are defined for:
axial thrust force, and/or
distributed lateral load.
Load types for unfactored loads are:
horizontal soil pressure,
two user-defined load types.
Factored loads are computed for each load-case
combination by multiplying the appropriate load factor by
the sum of loads of the same type. Summary reports of the
computed load-case combinations are generated by the
Optimization of Pile Designs
Several pile lengths may be automatically checked by the
program in order to help the user produce a design with an
optimum pile penetration. For this purpose, users can evaluate
the curve of pile-head deflections versus pile length.
Curves of flexural stiffness versus bending moment and/or
moment versus curvature are provided to review the adequacy of
the pile's section. In addition, the user may also observe
the interaction diagram of the modeled pile section.
The user may observe the nonlinear values of the
foundation stiffness matrix.
Users may input lateral load test results for direct
graphical comparison to computed pile response from LPILE.
This is helpful for calibrating input properties to optimize
Soil layer data structures and input screens are improved to
help the user enter data conveniently with defaulted values
providfed. Hints and notes were also introduced on input windows
to assist the user for data entry.
Over 100 error-checking messages have been provided, making
it simpler for occasional users to run the program and/or to
debug run-time errors of more experienced users.
The Graphics menu can produce quick displays of all results
contained in the output file, including:
pile deflection versus depth,
bending moment versus depth,
shear versus depth,
mobilized soil reaction versus depth,
mobilized pile EI versus depth,
deflection-moment-shear versus depth, and
deflection-curvature-moment versus depth.
Ability to display soil profile at side of most graphics.
A custom-control chart can be used to prepare various
engineering plots in high quality for presentation and report.
New features are provided so users can save and apply
templates to other presentation charts.
The files of input data and output data are text based and
may be directly accessed from within the LPILE program,
employing the user's preferred text editor or word processor.
A narrow output format can be selected so all the output
tables fit within a standard page width, which is convenient for
project documentation and reporting.
A well-documented Technical Manual is provided with
relevant theoretical equations. The User's Manual
includes a full description of all commands contained in the
program menu, and example problems that are supplied for
reference. The Technical and User's manuals are now distributed
in electronic form with the LPILE program.
Standard Windows operations, such as dialog boxes, speed
buttons, grid cells, clickable buttons, drop-down list of
options, and pull-down menu choices are all incorporated in
the LPILE program.