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NEES / PEEROpenSees Days 2011
Presented by the OpenSees CommunityAugust 22-23, 2011
Sponsored by:NEES through NEEScomm
Pacific Earthquake Engineering Research CenterNational Science Foundation
http://opensees.berkeley.edu/wiki/index.php/OpenSeesDays2011
WELCOME
On behalf of the: George E. Brown Network for Earthquake Engineering Simulation
(NEES)and the
Pacific Earthquake Engineering Research Center (PEER)
Simulation in Earthquake Engineering
• Research and practice is moving towards Performance-Based Seismic Engineering, which depends on high-fidelity models and simulation to assess performance.
• Simulation models capture knowledge from tests toleverage investment in limited experimentation.
• Community-based, open-source software for simulationpromotes innovation in research and advanced applicationsfor practice.
• NEES is supporting OpenSees to provide simulationcapability and integration with NEEScomm services forNEES research.
Vision for Simulation
Computational modeling and simulationis central to the vision of NEES totransform the development of newearthquake engineering solutions frombeing primarily based on experiments to abalanced use of simulation andexperimentation using computationalmodels validated by experimental data.
A close integration of moderncomputational models and simulationsoftware with other NEES applicationsand services will provide the earthquakeengineering community, and broadengineering users, new capabilities fordeveloping innovative and cost-effectivesolutions.
Observations on Current Situation
• Tight binding of models in research and commercialcodes is an impediment to new research andimplementation of models for professional practice.
• Embedding of computational procedures in codes makesit difficult to experiment and take advantage ofcomputing technology:– Parallel and distributed computers– Computational grids
• “Closed-source” is the norm, whereas other fields haveadopted “open-source” software for communitiesusers.
Building Blocks for Modern Simulation Code
ModelsMaterial, Element
Num
eric
al C
ompu
tatio
nA
lgor
ithm
s &
Sol
vers
Info
rmat
ion
Tech
nolo
gyD
atab
ase,
Vis
ualiz
atio
n, F
ram
ewor
ks,
Para
llel &
Grid
/Net
wor
k lib
rarie
s
Open-Source - Leave it out there for community
What is OpenSees?
• A software framework for simulation applicationsin earthquake engineering using finite elementmethods. OpenSees is not an application.
• A communication mechanism for exchanging andbuilding upon research accomplishments.
• As open-source software, it has the potential for acommunity code for earthquake engineering.
http://opensees.berkeley.edu• OpenSees has been under
development by PEER sincebefore 1997.
• Large group of developers anduser.
• NEES has supported integrationand extension since 2003.
• Open-source and royalty freelicense for non-commercial useand and internal commercial use.
• License must be obtained forsoftware developers includingOpenSees code in theirapplications.
• Written in C++ language ¤tly over 1000 classes(modules).
OpenSees Approach to Simulation
• Basic approach:– Modular software design for
implementing and integratingmodeling, numerical methods, and ITfor scalable, robust simulation
– Focus on capabilities needed forperformance-based engineering
– Programmable interfaces• Most users: a “application” for nonlinear
analysis. Fully scriptable.• Generally: a software framework for
developing simulation applications.
Structural Models as Aggregation Pattern
AnalysisModelBuilder
Builder - separate representationFrom construction
Domain
LoadPattern ElementNodeConstraints
Aggregation
Analysis Class for Simulation
DOF_Numberer AnalysisModel
SolutionAlgorithmSystemOfEqns
ConstraintHandler Integrator
Analysis DomainAnalysis class is responsiblefor performing an analysis on adomain and is formed byAggregation.
Beam-Column Models I
Elementu p
Basic System
v q
q1,v1q3,v3
q2,v 2
GeometricTran
u
p = afTq
p
u = afu
LinearLinearPDCorotational
Section
e s
e, s
s = asT!
A" dA
)(!"="
! = ase
Material
! !
No assumptions are made on section or material behavior;each level in the hierarchy can be defined independently ofother levels
σ
ε
Beam-Column Models II
s = bq
v = bTedx
0
L
!
e = av
q = aTsdx
0
L
!Basic System
v qq1,v1q3,v3
q2,v 2
Displacement Force
Material
ForceDeformationUniaxialMaterial
BeamWithHinges
2
FiberSectionFiber
UniaxialFiber
Concrete01 Steel01
σ
ε σ
ε s = asT! dA " as
T!( )
iAi
i=1
N f
#A$as = [1 –y z]
Form Follows Mechanics
OpenSees Scripting
1. wipe
2. source Units.tcl; # define units
3. source ParamList.tcl; # load up parameter values
4. source GMFiles.tcl; # load up ground-motion filenames
5. foreach Xframe $iXframe Hcol $iHcol Lcol $iLcol Lbeam $iLbeam
GIbIc $iGIbIc GrhoCol $iGrhoCol GPcol $iGPcol GMfact $iGMfact {
6. source Static.tcl; # load procedure for static analysis
7. source Dynamic.tcl; # load procedure for dynamic analysis
8. puts FRAME$Xframe........FRAME$Xframe........
9. puts STATIC_ANALYSIS
10. Static $Xframe $Hcol $Lcol $Lbeam $GIbIc $GrhoCol $GPcol $GMfact ;
11. puts DYNAMIC_ANALYSIS
12. foreach GroundFile $iGroundFile {
13. puts GroundMotion$GroundFile
14. Dynamic $Xframe $Hcol $Lcol $Lbeam $GIbIc $GrhoCol $GPcol $GMfact $GroundFile;
15. }
16. }
FRAME
GROUND MOTION
OpenSees has more capabilitiesthan the typical FE Application
Parallel&Distributed
NEES
The Network for Earthquake Engineering Simulation (NEES) is a sharednational network of 14 experimental facilities, collaborative tools, a centralizeddata repository, and earthquake simulation software.
NEEShub
• The power behind NEES at http://nees.org• Maintained and developed at Purdue by NEEScomm• A science gateway for education and research in earthquake engineering
Through a browser engineers can:• Upload and view experimental data• Browse online seminars and courses• Launch sophisticated tools using remote computational
resources (OpenSeesLab)
NEEShub Tools and Resources
Data Management
Simulation
Objective of OpenSees Days
• Describe modeling and analysis capability, includinghierarchy of system, element, section, material
• Overview of applications, structural andgeotechnical
• Show specific examples of nonlinear analysis• Provide hands-on starting-point for simulation tools• Introduce NEEShub capabilities using OpenSees• Motivation to use OpenSees for your simulation
problems….
What Should be Your Expectations?
• OpenSees is primarily a research tool at this time, but fairlystable and is used in professional practice
• As with any nonlinear analysis, it requires carefulconsideration of model and interpretation of results
• It is under continual development by students, faculty andother researchers
• User interface development lags behind computationaltechnology
• It is not bullet-proof• An investment of time and learning is required• The OpenSees open-source community requires contributions
for the community to succeed.
Thanks to:
• PEER staff (Heidi, Veronica, & Yolanda)• Silvia Mazzoni & Degenkolb Engineers• Andreas Schellenberg &• Rudi Eigenmann and Greg Rodgers• All the presenters
NEEScomm, PEER, and the National Science Foundation