motivation for stko to stko... · opensees, it creates an input (tool command language, tcl) and...
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STKO: a revolutionary toolkit for OpenSees
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• Motivation for STKOAn openbox tool to build and analyze models
• HDF5 databaseManage efficiently large I/O data
• STKO scripting interfaceImplement new tools with a Python Interface
• Computational efficiencyImplement large and complex models
SEMINAR OBJECTIVE
STKO: a revolutionary toolkit for OpenSees
• Introduction to STKO
STKO Scripting interface
Computational efficiency.
Parallel computation (OpenSEES MP)
and IMPL-EX algorithm
OUTLINE
STKO: a revolutionary toolkit for OpenSees
• Motivations
STKO Pre and post processor
Adopted database: HDF5
Proposed file format: MPCO
New recorder class: MPCORecorder
INTRODUCTION TO STKO
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
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MOTIVATIONSFE codes research vs profession
Linear, automatic checks, automatic
drawings or BIM (ifc or proprietary),
pre and post processor Black Box
Linear with some basic nonlinearities, automatic
checks, automatic drawings or BIM (ifc or
proprietary), pre and post processor
Black Box some interface with API
Black Box Linear and nonlinear, automatic mesh algorithms,
pre and post processor with some scripting capabilites
(Python, fortran etc.)
Professionals
No research
Professionals
Basic research
High level professionals
Research limited (black box)
OpenseesOpen Box, OpenSource, no mesh algorithms, no pre
and post-processor, TCL scriptsVery limited for professionals
Research limited (no GUI)
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
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MOTIVATIONSFE codes research vs profession
Linear, automatic checks, automatic
drawings or BIM (ifc or proprietary),
pre and post processor Black Box
Linear with some basic nonlinearities, automatic
checks, automatic drawings or BIM (ifc or
proprietary), pre and post processor
Black Box some interface with API
Black Box Linear and nonlinear, automatic mesh algorithms,
pre and post processor with some scripting capabilites
(Python, fortran etc.)
Professionals
No research
Professionals
Basic research
High level professionals
Research limited (black box)
Open Box, OpenSource, mesh algorithms, pre and
post-processor, TCL scriptsHigh level professionals
Research oriented with GUI
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
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STKO is a cutting-edge complex data visualization tool for
Opensees, it creates an input (Tool Command Language, TCL)
and output file which can be read with its advanced openGL
graphic interface.
STKO is the only pre and post processor that includes ALL
materials, elements, conditions and interactions offered in
Opensees.
STKO adopts HDF5 database library and Python-based
scripting interface for manipulation and customization of results.
MOTIVATIONSWhat is STKO
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Pre-processing
– Real-life structures often leads to complex models
– Input TCL files cannot always be written by hand
– We need an open box scriptable GUI to produce input files
Post-processing issues– High-volume output data
– Heterogeneous results
– Lack of visualization tools for results on fibers
– We need to manipulate and visualize large volume of complex data
Testing– Verification & Validation (NAFEMS)
MOTIVATIONSWhy we need a new tool
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Verification
– The process of determining that a computational model accurately
represents the underlying mathematical model and its solution.
– Code Verification – the mathematical model and solution algorithms are
working correctly. Among the Code Verification techniques, the most
popular method is to compare code outputs with analytical solutions;
– Calculation Verification - the discrete solution of the mathematical model is
accurate. Estimating the errors in the numerical solution due to
discretization
Validation
– The process of determining the degree to which a model is an accurate
representation of the real world from the perspective of the intended uses
of the model.
MOTIVATIONSVerification & Validation
What is Verification & Validation? NAFEMS. www.nafems.org
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
MOTIVATIONSVerification & Validation
Real problem
Conceptualmodel
Mathematical model
Physical model
Computationalmodel
Simulationresults
Simulationoutcome
Ok?
Experiment design
Experimental data
Experimental outcome
Mathematical modeling
Physicalmodeling
Implementation
Implementation
Calculation
Experimentation
UQ
UQ
Code verification
Calculationverification
Quan
tita
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co
mp
aris
on
Val
idat
ion
Pre
limin
ary
calc
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Revise model or experiment
NO
Adapted from:
What is Verification & Validation?
NAFEMS. www.nafems.org
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Motivations
• STKO Pre and post processor
Adopted database: HDF5
Proposed file format: MPCO
New recorder class: MPCORecorder
INTRODUCTION TO STKO
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
http://opensees.berkeley.edu/OpenSees/manuals/usermanual
Responsible for storing the objects created by
the ModelBuilder object and for providing
the Analysis and Recorder objects access to
these objects.
DomainModelBuilder Analysis
Recorder
Constructs the objects
in the model and adds
them to the domain
Monitors user-defined
parameters in the model
during the analysis
Responsible for
performing the
analysis
STKO PRE AND POST PROCESSOROpensees main abstractions
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Constructs the model (model builder), stores the objects (domain), selects the
parameters to record (recorder) and defines the analysis (analysis)
CAD importer, modeler and mesher
Based on OpenCascade library (https://www.opencascade.com/)
Scripting interface for linking with the external solver
Write tcl files
STKO PRE AND POST PROCESSORPre-processor
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
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Geometry/Interaction/properties/conditions
Advanced structured and
unstructured meshing tools
Complex nonlinear model analysis,
creation and visualization
STKO PRE AND POST PROCESSORPre-processor
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
http://opensees.berkeley.edu/OpenSees/manuals/usermanual
Constructs the objects in the model
and store them in the domain
DomainModelBuilder Analysis
Recorder
STKO PRE AND POST PROCESSORPre-processor
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Element Node MP_Constraint SP_Constraint LoadPattern Timeseries
Domain
DefinitionCondition
Geometry
Interaction (elements and nodes)
Local axes
Physical properties
Element properties
Mesh
http://opensees.berkeley.edu/OpenSees/manuals/usermanual
STKO PRE AND POST PROCESSORPre-processor - Domain
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Element Node MP_Constraint SP_Constraint LoadPattern Timeseries
Domain
DefinitionCondition
Geometry
Interaction (elements and nodes)
Local axes
Physical properties
Element properties
Mesh
http://opensees.berkeley.edu/OpenSees/manuals/usermanual
STKO PRE AND POST PROCESSORPre-processor –Domain – Element and node
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Exchange
Edit
Sets
Points
Curves
Surfaces
Solids
Boolean
STKO PRE AND POST PROCESSORPre-processor - Geometry
Geometry is divided
into eight sections:
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Interaction Modeling defines the links
among nodes or elements.
It is used to simulate the relationship
among elements like beam-column,
beam-beam, solid-beam, general
structural constraints etc.
STKO PRE AND POST PROCESSORPre-processor - Interaction
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor - Interaction
Example Interaction Type:
Node-to-Node links
Slave geometries (faces)
Master Geometry (line)
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor – Local Axes
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor – Physical Properties
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor – Physical Property -Materials
nD Materials
Uniaxial
Materials
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor – Physical Property - Sections
Sections
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor – Physical Property –Special purpose
Special Purpose is a
“container” in which more
physical properties coexist
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor – Physical Property –Element property
All the element in Opensees
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor – Physical Property –Element property
Order:
Linear (2 or 3 nodes),Triangle (3 or 6 nodes)Quadrilateral (4, 8 or 9 nodes),Tetrahedra (4 or 10 nodes)Hexahedra (8, 20 or 27 nodes –Serendipity)
Algorithm:
StructuredUnstructured
Topology:
Triangular/TetrahedralQuadrilateral/Hexahedral
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Element Node MP_Constraint SP_Constraint LoadPattern Timeseries
Domain
DefinitionCondition
Geometry
Interaction (elements and nodes)
Local axes
Physical properties
Element properties
Mesh
http://opensees.berkeley.edu/OpenSees/manuals/usermanual
STKO PRE AND POST PROCESSORPre-processor –Domain – Timeseries
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor –Definition
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Element Node MP_Constraint SP_Constraint LoadPattern Timeseries
Domain
DefinitionCondition
Geometry
Interaction (elements and nodes)
Local axes
Physical properties
Element properties
Mesh
http://opensees.berkeley.edu/OpenSees/manuals/usermanual
STKO PRE AND POST PROCESSORPre-processor –Domain – MP/SP_Constraint, LoadPattern
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor –Condition
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
http://opensees.berkeley.edu/OpenSees/manuals/usermanual
DomainModelBuilder Analysis
Recorder
Responsible for
performing the
analysis
STKO PRE AND POST PROCESSORPre-processor –Analysis
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Introduction to OpenSees and Tcl/Tk OpenSees Days Shanghai 2011, 1Frank McKennaUC Berkeley
STKO PRE AND POST PROCESSORPre-processor – what is an analysis in Opensees
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor –Analysis - Static
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor –Analysis - Transient
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO is implemented for all OpenSees interpreters:
OpenSees.exe
OpseseesSP.exe
OpenSeesMP.exe
STKO PRE AND POST PROCESSORPre-processor –Analysis - Interpreters
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
STKO PRE AND POST PROCESSORPre-processor –Analysis – OpenseesMP Domain decomposition
10 Partitions
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
30 Partitions
STKO PRE AND POST PROCESSORPre-processor –Analysis – OpenseesMP Domain decomposition
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
http://opensees.berkeley.edu/OpenSees/manuals/usermanual
DomainModelBuilder Analysis
Recorder
Monitors user-defined
parameters in the
model during the
analysis
STKO PRE AND POST PROCESSORPre-processor –Recorder
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
_ HDF5-based output database (https://www.hdfgroup.org/)
(originally developed at the National Center for Supercomputing
Applications)
_ Standard plot tools
_ Advanced plot tools for beam elements (fibers, zero-length etc.)
_ Scripting interface for interaction with the Database (in process)
STKO PRE AND POST PROCESSORPost-processor
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Motivations
STKO Pre and post processor
• Adopted database: HDF5
Proposed file format: MPCO
New recorder class: MPCORecorder
INTRODUCTION TO STKO
For more info:
The HDF Group, "Hierarchical Data Format, version 5," 1997-2017. [Online]. Available: http://www.hdfgroup.org/HDF5/
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
_ Opensource (BSD license) library
_ Completely portable file format
_ No limits on the number or size of data objects in the collection
_ Runs on a range of computational platforms, from laptops to massively parallel systems
_ Several languages: C, C++, Fortran90, Java, Python
_ Parallel I/O
STKO ADOPTED DATABASEHDF5 – Why HDF5?
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
HDF. Hierarchical Data Format is
a set of file formats designed to store
and organize large amounts of data
_ Hierarchical structure
_ Groups (directories)
_ Datasets (data)
_ Attributes (metadata)
STKO ADOPTED DATABASEHDF5 - What does a HDF5 file look like?
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Motivations
STKO Pre and post processor
Adopted database: HDF5
• Proposed file format: MPCOHow to lay out complex data
New recorder class: MPCORecorder
INTRODUCTION TO STKO
For more info:
The HDF Group, "Hierarchical Data Format, version 5," 1997-2017. [Online]. Available: http://www.hdfgroup.org/HDF5/
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Model (+ model stages)
_ Nodes
_ Elements
Geometries + standard and custom integration rules
_ Sections and materials + assignments
Results
_ Results stored on nodes
_ Results stored on elements
On element nodes
On integration points
On sub-integration points (fibers)
PROPOSED FILE FORMATMPCO - What do we need to store in our output file?
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
• Changes in the original model
• Added/removed elements/nodes
From OpenSees Structural Examples
Infill Wall Model and Element Removal
M. Selim Gunay and Khalid M. Mosalam, University of
California, Berkeley
http://opensees.berkeley.edu/wiki/index.php/Infill_Wall_Mode
l_and_Element_Removal
PROPOSED FILE FORMATMPCO – Multi stages
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
PROPOSED FILE FORMATMPCO – Each model stage group contains
_ Model information
_ Results
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Gauss points Fibers
PROPOSED FILE FORMATMPCO – Model information
• Nodes• Elements
_ Geometry
_ Standard and/or custom
integration rules
• Section assignments_ Element and gauss assignments
_ Fiber data
_ Fiber materials
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
PROPOSED FILE FORMATMPCO – Results
_ Results on nodes
_ Results on elements
On element nodes
On integration points
On sub-integration points
(fibers)
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
_ Results on nodes
Displacement/Rotation/Reaction
1 Dataset with selected node IDs
1 Data group
1 Dataset for each time step
PROPOSED FILE FORMATMPCO – Results on nodes
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
• Groups based on:_ Element type
_ Size of connectivity
_ Type of integration rule
_ Type of cross sections
• Each group contains:_ Metadata group with:
Number of components + labels
Node or gauss ID
Multiplicity
_ 1 Dataset with selected element IDs
_ 1 Data group
_ 1 Dataset for each time step
PROPOSED FILE FORMATMPCO – Results on elements
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Motivations
STKO Pre and post processor
Adopted database: HDF5
Proposed file format: MPCO
New recorder class: MPCORecorderImplementation of the HDF5 based recorder in OpenSees
INTRODUCTION TO STKO
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
NEW RECORDER CLASSMPCORecorder
Implemented in version 3.0.0 of Opensees
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
NEW RECORDER CLASSMPCORecorder
Implemented in version 3.0.0 of Opensees
STKO: a revolutionary toolkit for OpenSeesIntroduction to STKO
Displacements/velocity/acceleration Gauss plots/Strain stresses/Lumped plasticity
Distributed plasticity / fiber model/strain stresses
PROPOSED FILE FORMATMPCO – Plots
STKO: a revolutionary toolkit for OpenSeesScripting Interface
Introduction to STKO
• STKO Scripting interface
Example: automatic calibration of constitutive models in
STKO Pre-Processor
Computational efficiency.
OUTLINE
STKO: a revolutionary toolkit for OpenSeesScripting Interface
STKO SCRIPTING INTERFACE
STKO Scripting interface: the X-Object
Adopted constitutive model
Automatic calibration of material parameters
Automatic confinement
STKO: a revolutionary toolkit for OpenSeesScripting Interface
Built-in CAD environment
• Create geometries
• Mesh the model
• Define local axes
X-Object components
• Link the STKO pre
processor to OpenSEES
• Uses Python scripting
language
• Customizable: new
components can be
implemented by users
STKO SCRIPTING INTERFACEThe X-Object
STKO: a revolutionary toolkit for OpenSeesScripting Interface
Mandatory methods
makeXObjectMetaData
writeTcl
Optional methods
onEditBegin
onAttributeChanged
What an X-Object plug-in look like?
Custom component in OpenSEES
ConcreteDamage.dll
Write a X-Object to link with STKO pre-processor
ConcreteDamage.py
STKO SCRIPTING INTERFACEThe X-Object
STKO: a revolutionary toolkit for OpenSeesScripting Interface
ConcreteDamage.py
(Mandatory)
makeXObjectMetaData
• Define a prototype of the new component
• Create all attributes (1 for eachmaterial paramter)
• Add all attributes to the X-Object meta data
STKO SCRIPTING INTERFACEHow to write the X-Object
(Optional)
onEditBegin
onAttributeChanged
• To support inter-parameterdependency
• To improve visual experience
STKO: a revolutionary toolkit for OpenSeesScripting Interface
ConcreteDamage.py
(Mandatory)
writeTcl
• Get values of parameters of
the current instance of X-
Object
• Do some processing…
• Write to TCL file
STKO SCRIPTING INTERFACE:How to write the X-Object
STKO: a revolutionary toolkit for OpenSeesScripting Interface
STKO SCRIPTING INTERFACE
STKO Scripting interface: the X-Object
Adopted constitutive model
Automatic calibration of material parameters
Automatic confinement
STKO: a revolutionary toolkit for OpenSeesScripting Interface
Problem
–Non-linear constitutive models have parameters difficult to identify
Objectives
– Create 2 automatic plug-ins for STKO pre-processor:
• Automatic calibration of material parameters from experimental
results
• Automatic calculation of confined materials starting from their
unconfined counterparts and the cross section layout
– The time required to build a model and the possibility of error
STKO SCRIPTING INTERFACEExample: parameter calibration with genetic algorithm
Luisa Berto, Guido Camata, Massimo Petracca, Anna Saetta, Diego Talledo. 2019. Automatic Calibration of
Constitutive Models in STKO Pre-Processor. Opensees Days Eurasia, Hong Kong,20-21 June.
STKO: a revolutionary toolkit for OpenSeesScripting Interface
STKO SCRIPTING INTERFACE
STKO Scripting interface: the X-Object
Adopted constitutive model
Automatic calibration of material parameters
Automatic confinement
STKO: a revolutionary toolkit for OpenSeesScripting Interface
Adopted constitutive model:
_ 2-parameter continuum damage model (d+, d-)
_ Uniaxial version of the model presented in: Tesser L., Filippou F.C., Talledo D.A., Scotta R., Vitaliani R. 2011. Nonlinear Analysis Of R/C Panels By A Two Parameter Concrete
Damage Model. COMPDYN 2011 III ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake
Engineering M. Papadrakakis, M. Fragiadakis, V. Plevris (eds.) Corfu, Greece, 25–28 May.
_ Captures the unilateral effect and stiffness recovery on crack closure
_ A+, A- and B- parameters are complex to calibrate
A genetic algorithm is a stochastic method for function optimization
based on the mechanics of natural genetics and biological evolution
STKO SCRIPTING INTERFACEExample: parameter calibration with genetic algorithm
STKO: a revolutionary toolkit for OpenSeesScripting Interface
Cauchy stress
Damage thresholds
Damage indices
STKO SCRIPTING INTERFACEExample: parameter calibration with genetic algorithm
STKO: a revolutionary toolkit for OpenSeesScripting Interface
STKO SCRIPTING INTERFACEExample: parameter calibration with genetic algorithm
Notion of Natural Selection
Selection of fittest individuals from
a population.
They produce offspring which inherit
the characteristics of the parents and
will be added to the next
generation.
If parents have better fitness, their
offspring will have a better chance to
survive.
Iterate and at the end, a generation
with the fittest individuals will be
found.
STKO: a revolutionary toolkit for OpenSeesScripting Interface
.
Here a genetic algorithms is
used to find input parameters
that best match the
experimental results
STKO SCRIPTING INTERFACEExample: parameter calibration with genetic algorithm
STKO: a revolutionary toolkit for OpenSeesScripting Interface
STKO SCRIPTING INTERFACE
STKO Scripting interface: the X-Object
Adopted constitutive model
Automatic calibration of material parameters
Automatic confinement
STKO: a revolutionary toolkit for OpenSeesScripting Interface
STKO SCRIPTING INTERFACEExample: automatic confinement
User input and automatic computation
• Concrete exhibits higher strength and ductility under triaxial stress
states
• The softening branch is less steep when confined
• User input of cross section and reinforcement layout
• User input of unconfined concrete model
• Automatic calculation of the confined concrete model for the core
using:
• Eurocode 2
• Eurocode 8 part 3
• Italian Standard
STKO: a revolutionary toolkit for OpenSeesScripting Interface
STKO SCRIPTING INTERFACEExample: automatic confinement
Pseudo-Code:
write unconfined material;
for each section {
compute confinement parameters;
write confined material;
write core fiber with confined material;
write cover fibers with unconfined material;
STKO: a revolutionary toolkit for OpenSeesScripting Interface
STKO SCRIPTING INTERFACEExample: automatic confinement
STKO: a revolutionary toolkit for OpenSees
Introduction to STKO
STKO Scripting interface
• Computational efficiency Parallel computation (OpenSEES MP) and IMPL-EX
algorithm
OUTLINE
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
COMPUTATIONAL EFFICIENCY
Approaches for modeling of masonry structures
Tension-Compression Damage model
IMPL-EX algorithm
Numerical application
Conclusions
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
Macro-modelingMicro-modeling
ComputationalHomogenization
COMPUTATIONAL EFFICIENCYMicro/Macro Modeling of materials
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
Micro-modeling
Pros:
Easy to model
Low computational costs
Cons:
Complex constitutive models (damage-
induced anisotropy) not available in most
software
Mesh dependent with softening material
models
Pros:
Simple constitutive models for micro-
structural components
Mesh independent
Cons:
Complex to model the whole micro-
structure
High computational costs
VS
COMPUTATIONAL EFFICIENCYMicro/Macro Modeling of materials
Macro-modeling
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
Micro-modeling
STKO GUI
STKO PARTITIONER
OPENSEES MP
COMPUTATIONAL EFFICIENCYMicro/Macro Modeling of materials
Pros:
Simple constitutive models for
micro-structural components
Mesh independent
Cons:
Complex to model the whole
micro-structure
High computational costs
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
COMPUTATIONAL EFFICIENCY
Approaches for modeling of masonry structures
• Tension-Compression Damage model
IMPL-EX algorithm
Numerical application
Conclusions
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
• 2-parameter continuum damage model (d+, d-)
• Reference: Cervera M., Oliver J., Faria R., 1995. Seismic evaluation of concrete dams via continuum damage models. Earthquake Engineering and
structural Dynamics. Vol. 24, Issue 9. September. Pag. 1225-1245
• Tension/Compression stress split based on a spectral decomposition of the
effective stress tensor
• Captures the unilateral effect and stiffness recovery on crack closure
where:
COMPUTATIONAL EFFICIENCYTension-Compression damage model with IMPL-EX algorithm for
micromodeling of Masonry/Concrete materials
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
• 2 independent failure criteria for the tensile and compressive parts
• Failure criteria based on: Lubliner J., Oliver J., Oller S., Oñate E. 1989 A plastic-damage model for concrete. International Journal of Solids and Structures.
Volume 25, Issue 3, Pages 299-326
two scalar measures, termed as
equivalent stresses τ+ and τ−
COMPUTATIONAL EFFICIENCYTension-Compression damage model failure criteria
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
• Damage growth is an irreversible process
• r, damage thresholds represent the largest values ever attained by the equivalent
stresses (τ-, τ+)
• Damage indices (d+, d-) are functions of the damage thresholds (r-, r+)
COMPUTATIONAL EFFICIENCYTension-Compression damage model thresholds (r-,r+) and damage
indeces (d-, d+)
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
COMPUTATIONAL EFFICIENCY
Approaches for modeling of masonry structures
Tension-Compression Damage model
• IMPL-EX algorithm
Numerical application
Conclusions
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
2-stage integration
• Explicit extrapolation:
• internal variables at the current time step are explicitly extrapolated
from those at the two previous time steps.
• Used to compute global equilibrium (OpenSEES: in method
‘setTrialStrain’)
• No dependency on the current strain
• Step-wise linear
• Tangent matrix remains symmetric and positive definite (secant
matrix)
• Implicit correction:
• Replaces explicit internal variables with their implicit counterparts
(OpenSEES: in method ‘commitState’)
• Reduces the error generated by the explicit stage
COMPUTATIONAL EFFICIENCYIMPL-EX algorithm Mixed Implicit-Explicit Integration Scheme
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
COMPUTATIONAL EFFICIENCYIMPL-EX algorithm Mixed Implicit-Explicit Integration Scheme
Oliver J., Huespe A.E., Cante C. 2008. An implicit/explicit integration scheme to increase computability of non-linear material and
contact/friction problems. Computer Methods in Applied Mechanics and Engineering. Volume 197, Issues 21–24, 1 April, Pag. 1865-
1889
Explicit extrapolation at material level
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
COMPUTATIONAL EFFICIENCY
Approaches for modeling of masonry structures
Tension-Compression Damage model
IMPL-EX algorithm
• Numerical application
Conclusions
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
Two-story masonry building tested at the university of PaviaMagens G, Kingsley G., Calvi G.M. 1995 Seismic testing of a full-scale two-story masonry building: Test procedure and measured experimental
response. ruppo nazionale Difesa dai terremoti (Italy) 41 pages
COMPUTATIONAL EFFICIENCYNumerical applications
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
COMPUTATIONAL EFFICIENCYNumerical applications. Pre-processor
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
COMPUTATIONAL EFFICIENCYNumerical applications. Post-processor
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
Numerical prediction of the d+/d- damage micro-model
COMPUTATIONAL EFFICIENCYNumerical applications. Pre-processor
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
Numerical prediction of the d+/d- plastic-damage micro-model
𝜎 = 1 − 𝑑𝑝+ 𝜎𝑒
+ + 1 − 𝑑𝑝− 𝜎𝑒
−
𝜎𝑒 = 𝐶0: (𝜀 − 𝜀𝑝)
𝜎 = 1 − 𝑑𝑝+ 𝜎+ + 1 − 𝑑𝑝
− 𝜎−
𝜀𝑝 = 𝜀𝑝 + 𝜆+ 𝜎+
𝜎++ 𝜆−
𝜎−
𝜎−
COMPUTATIONAL EFFICIENCYPlastic damage model
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
COMPUTATIONAL EFFICIENCY
Approaches for modeling of masonry structures
Tension-Compression Damage model
IMPL-EX algorithm
Numerical application
• Conclusions
STKO: a revolutionary toolkit for OpenSeesComputational Efficiency
• Micro-modeling is very accurate even if using simple
constitutive models
• Computational costs of micro-modeling can be drastically
lowered:
– Using parallel computation (OpenSEES MP)
– Using appropriate integration algorithms (IMPL-EX)
COMPUTATIONAL EFFICIENCYConclusions