GROUP 2022
New features include:
- MOST importantly, the largest and most complex new feature of GROUP v2022
is the ability to model
FLEXIBLE PILE CAPS using finite-element methods, with combination of
plate (thin or thick) and beam elements. This feature is not standard but rather
an
OPTIONAL PAID UPGRADE since it introduces large complexities that are not necessary
for most users that can remain with the much simpler models with RIGID pile caps.
Options > Pile-Cap Type > Flexible Pile Cap
and to create a model with flexible pile cap
File > New from Template...
- Added the following
new soil types (p-y criteria) for consistency with the LPILE program:
- Liquified Sand Hybrid Model
- Piedmont Residual
- Massive Rock
- Loess
Data > Soil Layers
- New option to define a pile cap with
a circular shape.
Data > Pile-Cap Options
and to create
a circular pile layout with circular cap.
File > New from Template...
- Added a new feature so users can specify a
reduction factor (p-y multipliers) along depth on embedded pile caps.
Options > Reduction Factors for Lateral Loads along Depth
Data > Pile-Cap Options
- Updated all codes to 64-bit processors/operating system so as
to enable efficient runs of larger models.
- This version also consolidates several small program updates made in the
past 2 years made while still under the previous 2019 release.
GROUP 2019
Incorporate new features including
- Added
a new feature related to lateral
loads induced by Soil Movements
Data > Loading > Edit Load Case x > Edit Soil Movement Data
Users may now specify:
-
Different soil movements for each load case.
-
Different soil movements for each pile in the group
model.
-
New option to select a nonlinear section model
using the Equivalent Elastoplastic Moment Curvature
. This is a definition used by engineers and
consultants in seismic areas (based on technical
documentation from CALTRANS) to define the formation of
plastic hinges in piles analyzed under extreme loading or
for push-over analyses. The post-hinge behavior is
clearly defined in the deflection curves for pushover
models. When Equivalent Elastoplastic Moment Curvature is
used and pushover analysis is performed, the resulting
plots of pushover analyses display marks and legends for
the points where the plastic hinges are developed (first
and second plastic hinges, when applicable). This feature
is available under
Data > Pile Cross Section > Edit Section x > Compute Equivalent ElastoPlastic M-phi (CALTRANS) for nonlinear sections only.
-
Introduces the functionality to import data files
with complete soil layering and properties defined by
the new EnCPT v2019
program. The separate EnCPT software allows
geotechnical consultants to offer to their clients new
services for detailed interpretation of their CPT tests
into various layering and soil properties that can be
used quickly and customized in GROUP v2019
models. Access this feature through
Data > Import Soil Layers from EnCPT Soil File
-
New feature to
import soil layering
and properties plus pile section(s) data
from LPILE v2018 or v2019
models. Access this feature through
Data > Import Soil and Section from LPILE Model
-
New feature to
import nonlinear flexural stiffness section
data from LPILE v2018 or
v2019 models. Access this feature through
Data > Import Nonlinear EI Data Generated by LPILE
-
A standard drop-down selection of Carbon Fiber Composite
Cable (CFCC) strands are now available for all prestressed
pile sections.
-
Users can choose to turn off the soil-layering correction
criteria in models with multiple layers or to only use for
layers of different soil types (p-y criteria).(Selected
with check marks under the Options menu).
-
Added a new feature to perform incremental/pushover
analysis for any load case, where users can select various
Loads or Displacements to keep constant during the
pushover analysis.
-
An option is added so models may consider Non-Symmetric
reinforced concrete sections for estimation of moment
curvature (which can now be different if the pile is
bending in one direction or the opposite). This was not
available in previous releases of GROUP.
-
Users may now specify Elastic sections with specified
moment capacity (in both directions of bending).
-
Users may now enter values for the perimeter of the pile
section which may be useful for cases where the user wants
to override the internal computations (which will affect
the load transfers in side resistance).
-
Added a new feature that allows users to perform embedded
pile cap analysis using equivalent lateral springs. This
new feature may help to reach convergence particularly in
cases of small lateral displacements.
-
Improved the internal computations of axial
load-vs-settlement curves with the following changes:
-
New computations of t-z curves at each integration
point of the piles (previously done at 3 points per
soil layer).
-
Use diameter at each pile section to compute the
load-vs-settlement curves. Previous version used
diameter at the top of the piles.
-
For batter piles in sand layers, the new GROUP program now
computes the proper transfer in side resistance for the
inclined length plus it adds the additional benefit of
normal stress from overburden pressure.
-
Released updated
Technical, User’s
and Examples Manuals.
GROUP 2016
Release cycle for GROUP 2016 extended from year 2015 through
2018.
Incorporate new features including
-
Automatic computation of Nonlinear Bending Stiffness for
various pile sections (defined by user).
-
Enhanced the program to use negative vertical coordinates
for pile heads.
-
Enhanced the program so the ground line can start at any soil layer.
-
Enhanced program to use vertical projection while using batter piles
-
Enhanced the program to generate different axial load vs
settlement curve for piles with same pile property but
placed at different ground elevations.
-
Enhanced the program to extend interpolation of L-D and
T-R Curves if displacement is larger than generated or
user-defined curve.
-
Increased maximum number of piles to 2500.
-
New computation of reduction factors for lateral loading
based on average diameter.
-
Allows for the rotation of the section with respect to the x axis.
-
Ensures compatibility with LPILE for the internal
computation of default values for kp-y and
ε50.
-
Corrected printing of Labels for Rotational Spring in Z
and Y directions
-
Used values of ε50 defined for silt layers.
-
Added option for user to enter an equivalent diameter for
the pile cap.
-
Added option for user to color piles based on pile
properties and cross sections.
-
Improved drawing of pile cap when pile head coordinates
are not the same for all piles.
-
Improved drawing of soil layers when ground line is not
the same for all piles.
-
Added option to import soil properties and cross sections
from LPILE.
-
Added option to shift all piles and/or soil layers in
vertical direction.
-
Added option to export plots to pre-formatted excel
spreadsheets.
-
Fixed unit conversion in the New from Template Window.
-
Added option to draw pile caps of irregular shape.
-
Added option to change format of displayed values (3D View).
-
Added Option to display maximum effects based only on
visible or selected piles.
-
Added option to hide or show piles by right-click mouse button.
-
User's Manual was divided into User’s Manual and Example
Manual.
-
Introduced an alternative p-y criteria Modified
Soft Clay w/ Initial K that performs with better
mathematical convergences than the original Soft Clay
(Matlock).
GROUP 2014
Incorporate new features including
-
Ability to import moment curvature generated from models
in the LPILE program.
-
Ability to import p-y curves generated from models in the
LPILE program.
-
Added two soil models, API Soft Clay with
variable J and Elastic Subgrade.
-
Revised input units for various parameters, i.e, depth,
specific weight, section dimensions.
-
New version can estimate some some soil parameters that
may be missing from the input, (ε50,
kpy) in soil types where it may be applicable.
-
Added an option to analyze a case specifying displacements
at the pile cap level. The user may combine specified
displacements and applied forces in different degree of
freedoms.
-
Added tool buttons to navigate through load cases and
combinations.
-
Implemented the use of parallel processing, so the program
can perform the analysis using more than one processor
that helps reducing the analysis time.
GROUP 2013 (v8 Data Format)
Group is now released under maintenance contract. All users
with active maintenance contracts can download all program
updates and revisions from the Ensoft website
(www.ensoftinc.com) without additional charges. Thus, users
are no longer purchasing version updates to the program.
Instead, they are purchasing extensions to their maintenance
contracts.
The version numbers now used for GROUP has three parts that
indicate the year of the initial release, the data file
format version number, and the update/revision number. The
meaning of the versions numbers is described below.
-
The first number refers to the year of the initial program
release. Te first number also indicates the release of
major new features of the program.
-
The second number is the version number of the data file
format. This is changed whenever there is a change in the
data file format (usually only during major
releases).
-
The third number indicates the update/revision number. The
update/revision number is incremented every time there is
a small new feature or repair of the program or the
accompanying documentation.
The new features for this release are summarized below:
-
New feature for estimating the equivalent elastic
stiffness matrix.
-
New ability to analyze models with lateral soil movements
specified by the user.
-
Included option to define reduction factors for lateral
loading along depth.
-
Estimated the axial displacement and axial forces along
piles. This option is not available when user defined
axial load displacement curve is used.
-
Able to compute the displacements in global
directions.
-
New option to define a tapered section along the pile
length.
-
New option to change the modulus of elasticity along the
pile depth.
GROUP v.8.0 (2010)
-
The program allows for models with a maximum of 2000 piles
in a group.
-
A New from Template option has been added, so the program
can easily generate basic rectangular or circular pile
group layouts.
-
The program includes various additional options for loading:
-
The program allows the user to perform analyses under
various load cases. Each load case may be due to
concentrated loads at the pile cap and/or distributed
lateral loads at the piles.
-
Concentrated loads at the pile cap may be defined for
any position; the program will compute the equivalent
concentrated load at the origin for analyses.
-
Distributed lateral loads at the piles can be defined
relative to the local axes as well as the global axes.
For loads oriented at the global axes in batter piles,
the axial component may be included as a concentrated
load at the pile head.
-
The program allows the user to perform analyses under
various load combinations. Load combinations are set
by load factors applied at the load cases previously
defined by the user.
-
Maximum and minimum envelopes may be computed for both
load cases and load combinations.
-
The program includes the option to compute both the
Flexibility and Stiffness Matrix for different levels
of loading.
-
A Cross Section dialog was included to allow the user to
define circular, rectangular and I sections. However, for
noncircular sections the equivalent diameter must be
defined by the user.
-
The program will be able to transform a 2D pile layout
into a 3D layout. The program can also convert a 3D pile
layout into a 2D layout; however, this conversion may not
be accurate for non-symmetrical configurations.
-
Inputs for soil properties have been rearranged so the
user is only requested to enter the mechanical properties
that are appropriate to the selected type of soil.
-
The program allows a mix of input defined curves (p-y
curves, axial load-displacement curves and torque-rotation
curves) and automatically generated curves in the same
model.
-
The program provides a summary table of output data, which
includes maximum and minimum effects for pile heads over
the pile length.
-
User can select the information to be printed, which is
convenient when the size of the output file becomes very
large due to a large number of piles and load cases.
GROUP 7.0 (2006)
-
The p-y criteria for liquefiable sand developed by
Rollins, et al. (2003), and p-y criteria for stiff clay
with user-specified initial k values, recommended by Brown
(2002), were added in Version 7.0.
-
The program requires data for unit side friction at the
top and bottom of each layer as well as the unit tip
resistance for generating the axial stiffness (axial
load-displacement relationship) at the pile head. Version
7.0 internally provided the estimated unit side friction
and tip resistance based on the strength data of soil
layers and commonly accepted empirical equations.
However, the program still allowed those data specified
externally for the user to control the axial capacity of
piles based on the local recommendations.
-
Version 7.0 generated more types of graphs than previous
versions. More importantly, the program plots the force
and displacement on the pile cap, such as the axial force
(tension and compression) of each pile on the pile cap,
the lateral forces (shear and moment) of each pile on the
pile cap, and the displacement of the pile cap in
different directions.
-
The program provided a summary table of output data, which
is convenient when the size of the output file becomes
very large due to a large number of piles in the
application.
-
The program implemented a new algorithm that significantly
improved the nonlinear iterations and accuracy of the
solution.
GROUP 6.0 (2003)
-
The program allowed for up to 500 piles in a group, and
each pile could have different EI values in orthogonal
directions.
-
GROUP v6.0 considered the nonlinear bending stiffness (EI)
of each pile during computation. The user can enter
nonlinear moment-curvature curves under different axial
loads for each pile.
-
For closely-spaced piles, the pile-soil-pile interaction
can be taken into account by introducing reduction factors
for the p-y curves used for each single pile. These
factors were modified based on a study by Reese and Van
Impe (2001).
-
GROUP v6.0 included advanced 3-dimensional graphics to
represent the response of each pile in the group. The
user has options that allow for the display of the
deformed/undeformed shape of pile groups, stress contours,
soil layers, and many others.
GROUP 5.0 (2000)
-
GROUP v5.0 allowed the user to analyze the behavior of
pile groups using either a 2 or 3-dimensional model. The
2-dimensional model is sufficient and convenient if the
piles are arranged symmetrically to the applied load.
Otherwise, a 3-dimensional model is recommended for
analyzing the nonlinear behavior of pile groups.
-
GROUP v5.0 solves the nonlinear response of each pile
under six components of loadings and assures compatibility
of geometry and equilibrium of forces between the applied
external loads and the reactions of each pile head.
-
Torsional resistance curves could be generated by the
program.
GROUP 4.0 (1996)
-
Standard Windows operations, such as dialog boxes, grid cells,
clickable buttons, drop-down list of options, and pull-down submenus
were all incorporated to ease data entry.
-
Improved file-management features were included to help
the user during program execution. A standard
single-program module was introduced for data input,
program execution, graphical observation of output-data
curves, and optional direct viewing of input or output
text files.
-
The online help file was also enhanced and could be loaded
during preparation of input data for quick consultation of
main operational features and basic technical
recommendations.
-
The graphical observation of output curves featured a new
interface that allowed the user to zoom into areas of
particular interest. The user may thus observe the
detailed behavioral measurements of any portion of the
depth of each pile group.
-
Three additional p-y criteria were added to the previously
existing four soil types. New soil criteria are available
for c-φ soils, the sand model recommended by the American
Petroleum Institute (API), and rock.
-
A new option that takes into account the lateral soil
resistance against embedded pile caps was introduced. The
theory and specific assumptions utilized for the
computation of lateral soil resistance on embedded pile
caps were included in the new Technical Manual.
-
The user was also provided with the option to specify a
reduction factor on the axial capacity of closely-spaced
piles.
GROUP 3.0 (1994)
-
The user was provided with updated technical information
on group-reduction factors for piles under lateral loads.
If the user wished to account for pile-soil-pile
interaction, the program could optionally generate
p-multipliers to automatically reduce soil resistance.
-
The new version provided data for evaluating pile-cap
stiffness levels, which are often used in structural
engineering models. Under this new option, the program
created curves of incremental loading versus pile-cap
movements and rotations. A conceptual modeling
application for the analysis of the behavior of a bridge
is shown in Figure 1.1. With curves similar to the one
shown in Figure 1.1c, the user was able to specify
pile-cap stiffness levels corresponding to a given range
of loading for their models of structural analyses.
-
GROUP 3.0 could accommodate up to 50 rows of piles in each
group analysis, compared to only 20 rows in previous
versions of the program.
-
Also, the input-editing module was improved to handle more
data points and soil layers.
-
New example problems are presented, including one for the
special case where the pile cap is installed below the
ground surface.
GROUP 2.0 (1990)
The second version of GROUP included a number of additional,
user-friendly features. The main improvements were on the
input and graphics modules. The input module introduced the
use of pull-down menus and grid cells for data entry. The
graphics module provided enhanced plots for pile deflection,
bending moment, shear, and soil resistance.
A subroutine was added to the main program to allow the
implementation of the t-z method to solve for the
settlement (or uplift) of a pile, based on soil properties
and pile geometry. The user was able to specify that the
program internally generate the settlement of a pile as a
function of axial load based on nonlinear load transfer in
skin friction and end bearing, which in turn may vary as a
function of distance below the ground surface.
GROUP 1.0 (1987)
The first version of GROUP internally generated the
nonlinear response of the soil in the form of p-y
curves for soft clay, stiff clay with or without free water,
and sand. The user was also allowed to input externally
generated p-y curves. The relationship between
vertical load and pile settlement (or uplift) had to be
externally specified by the user.