Post on 04-Jun-2018
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P P E E
E E R R OpenSees User Workshop 2003
Presented by the OpenSees CommunityGregory L. FenvesAugust 21-22, 2003
Sponsored by the National Science Foundationthrough the Pacific Earthquake Engineering Research Center
Context
PEER Research Program in Performance-BasedEarthquake Engineering.
Development of enabling technology is expectedof NSF research centers.
Many researchers and students for PEER ThrustArea Simulation and Information Technologyare contributing to technology development andapplication.
New initiatives such as NEES and MBS areencouraging new simulation methods andtechnology.
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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.
What is OpenSees?
A software framework for simulation applicationsin earthquake engineering using finite elementmethods. OpenSees is not a code.
A communication mechanism within PEER, and beyond, for exchanging and building uponresearch accomplishments.
As open-source software, it has the potential for acommunity code for earthquake engineering.
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Open-Source Community Simulation Framework
Conceptual Approach for Simulation
InformationTechnology Software framework,
Databases, Visualization,Internet/grid computation
Computation Algorithms,Solvers,Parallel/distributedcomputing
ModelsMaterial, component,system models
Simulation models,Performance models,Limit state models
Software Framework
A framework is a set of cooperating software components for building applications in a specific domain.
A framework dictates the architecture of the application. Itmust represent the design decisions common to the applicationdomain.
A frameworks is based on the assumption that an architecturewill work for most applications within the domain.
Loose-coupling of components within the framework isessential for extensibility and re-useability for applications.
Examples: Visualization (GLUT), MS Office, compilers ... A framework is not a code
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Simulation Software Alternatives
Compute Technology
Base Code
Elements
Input Language
User Interface
Traditional Code
Model Domain
Materials
Framework of Components
Solvers
Compute Technology
Elements
Databases
Solution Procedures
Other
V i s u a l i z a t i o n
M o d e l B u i l d e r s
Application ProgramInterface (API)
What Should be Your Expectations?
OpenSees is a research tool at this time, but fairlystable for regular use
As with any nonlinear analysis, it requires carefulconsideration of model and interpretation of results
It is under continual development by students, facultyand other researchers
User interface development lags behindcomputational technology
It is not bullet-proof An investment of time and learning is required
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Objective of Workshop
Describe modeling and analysis capability, includinghierarchy of system, element, section, material
Overview of applications, structural andgeotechnical
Provide specific examples of nonlinear analysis as astarting point
Introduction to user interfaces under development
Pointers to more information and user support
Beam-Column Models I
Elementu p
Basic System
v qq1,v 1q3,v 3
q2,v 2
GeometricTran
u
p = af T q
p
u = a f u
Linear LinearPDCorotational
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Section
e s
e , s
s = asT
A dA )( =
= as e
Material
No assumptions are made on section or material behavior;each level in the hierarchy can be defined independently ofother levels
Beam-Column Models II
s = bq
v = bT e dx 0
L
e = av
q = aT s dx 0
L
Basic Systemv q
q1,v
1q3,v 3
q2,v 2
Displacement Force
UniaxialMaterial Behavior
Material
UniaxialMaterial
Concrete01 Steel01 Hysteretic BiLinear
Also:EPPEPP-GapCloughPinchHardening
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Aggregate UniaxialMaterials
Material
UniaxialMaterial
SeriesMaterialParallelMaterial
Rapidly develop modelsfrom existing implementations,e.g., composite gapping material
aParallelMaterial
aLeafMaterialaSeriesMaterial
aLeafMaterial aLeafMaterial
,
Composite Pattern
Material
ForceDeformationUniaxialMaterial
BeamWithHinges
2
FiberSectionFiber
UniaxialFiber
Concrete01 Steel01
s = a sT
dA a sT ( )i Aii=1
N f
Aa s = [1 y z]
The Fiber abstraction keeps the FiberSection classunaware of the response it integrates, making for aflexible design; however, there is a performancepenalty associated with flexibility.
Form Follows Mechanics
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Beam-Column Modeling
Material
ForceDeformationUniaxialMaterial
NonlinearBeamColumn beamWithHinges
2
API
setTrialSectionDeformation()getStressResultant()getSectionTangent()getSectionFlexibility()com mitState()getType()
Distributed
plasticity
Concentrated
plasticity
f = bT f sL bdx
Organization of Workshop
Tcl command language; what is Tcl? Modeling commands
System, element, section, material hierarchy Analysis commands
Standard and advanced methods Basic examples and use of parameters Advanced structural and geotechnical applications Other user interfaces
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Thanks to:
Silvia Mazzoni Parshaw Vaziri Veronica Padilla Frank McKenna Michael Scott Boris Jeremic