Developer’s Workshop 21-23 August 2001opensees.berkeley.edu/.../Aug2001/ParticipantPresentation.pdfParticipant Presentation of Research Interests using OpenSees •Charley Hamilton,

Developer’s Workshop 21-23 August 2001

Participant Presentation of Research Interests using OpenSees•Halil Sezen, UC Berkeley

•Flexure, slip and shear element models for reinforced concrete columns

•Joel P. Conte, UC San Diego

•Exact Finite Element response Sensitivity Analysis

•Propagation of Uncertainties in Nonlinear Dynamic Analysis of Structures for Performance-Based Earthquake Engineering

•Finite Element Reliability Analysis

•K.C. Tsai , National Taiwan University

•A Platform for Inelastic Structural Analysis of 2D Systems (PISA2D)

•Zhaohui Yang, UC San Diego

•Geotechnical Applications Using OpenSees

•Zhaohui Yang, UC Davis

•Template Elastic-Plastic Framework

•3D Brick element

•Cenk Tort, University of Minnesota

•Research Objectives and Relation to OpenSees at the University of Minnesota

•Yihua Huang, Imbsen & Associates

•What we are going to use OpenSees for Bridge Engineering


Participant Presentation of Research Interests using OpenSees•Charley Hamilton, UC Irvine

•Advanced R/C bridge modeling in OpenSees

•Laura N. Lowes, U of Washington

•Simulation of RC Beam-Column Joint Response

•Xiaoyan Wu, UC Davis

•Dynamic Behavior of Coupled System

•3D Brick element

•Gilberto Mosqueda, UC Berkeley

•Using OpenSees for Analytical Simulations in Pseudodynamic Testing

•Chyuan-Hwan Jeng, U of Houston

•Seismic Evaluation of Prestressed Concrete Bridges

•Silvia Mazzoni, UC Berkeley

•Effects of Local Deformations on the Seismic Response of Bridge Structures

•Boris Jeremic, UC Davis

•Finite element formulation and implementation for inelastic behavior of solids (soils, concrete, rocks)

•Parallel Processing

•Template (a) Elastic-Plastic computations and (b) Finite Element technology

•Multiphysics (fully coupled solid-fluid formulation and implementation for example)

•Visualization


Participant Presentation of Research Interests using OpenSees•Michael H. Scott, UC Berkeley

•Research Interests with OpenSees

•Arash Altoontash, Stanford University

•Beam-column connection element

•Berk TAFTALI, Georgia Institute of Technology

•Fragility of Partially Restrained & Damped Ductile Connections

•Pedro Arduino, U of Washington

•Development of Geotechnical Capabilities in OpenSees

•Terje Haukaas, UC Berkeley

•Structural Reliability Analysis in OpenSees

•Charles Chadwell, UC Berkeley

•OSP – OpenSEES Post-Processor

•Mehrdad Sasani, Northeastern University

• Modeling Cyclic Response of RC Elements (with emphasize on shear response)

•Structural Reliability

•Afsin Saritas, UC Berkeley

•Nonlinear Analysis of Structures


Participant Presentation of Research Interests using OpenSees•Changho Choi, U Washington

•Improvement of Opensees’s Pre- and Post-ProcessingUsing GiD

•Kenneth J. Elwood, UC Berkeley

•Gravity Load Collapse of Reinforced Concrete Frames

•Kutay Orakcal, UC Los Angeles

•Macroscopic Modeling for Nonlinear Analysis of Reinforced Concrete Structural Walls

Halil Sezen

PEER, UC Berkeleye-mail: [email protected]

Flexure, slip and shear element models for reinforced concrete columns

• Exact Finite Element response Sensitivity Analysis

• Propagation of Uncertainties in Nonlinear Dynamic Analysis of Structures for Performance-Based Earthquake Engineering

• Finite Element Reliability Analysis

Joel P. ConteDepartment of Structural EngineeringUniversity of California, San DiegoE-mail: [email protected]

Graduate Students: Yuyi Zhang

Quan Gu

PPEEEERR

( )im edp dm

?(dv) G(dv | dm) dG dm|edp dG(edp | im) d?(im)= ∫ ∫ ∫

PEER Probabilistic Framework:

Reliability Analysis in OpenSees

Simulation of structural behavior

Structuralresponse

• Response sensitivity• Probability estimates• Reliability sensitivity measures• Importance measures

Random/uncertain material, geometry and load variables

Limit-state functions

Sensitivity and Reliability analysis

Finite element analysis

Structuralmodel

Joel P. Conte, University of California, San Diego ([email protected])

• Materially-nonlinear equation of motion (in semi-discretized form):

θ = scalar sensitivity parameter (constitutive material parameter or discrete loading parameter)

• Solution strategy for integrating the equations of motion:

– Time stepping algorithm (e.g., Newmark’s method)

– Newton-Raphson incremental-iterative procedure using consistent linearization:

• Exact sensitivity of nonlinear finite element response:

– Exact differentiation of the numerical finite element algorithm with respect to θ:

Exact Finite Element Response Sensitivity Analysis

( ) ( ) ( ) ( ) ( )( ) ( ) ( )t t t tθ θ + θ θ + θ θ = − θ θgM u , C u , R u , , M Lu ,&& & &&

( )idyn i+1 iT n n+1n+1

d = ΨK u i+1 i+1 i i+1n+1 n n n+1 n? d= + = +u u u u u

( )dyn 1T 11

+++

∂= Γ

∂θn

nn

uK


Applications of Exact Finite Element Response Sensitivity Analysis

• Sensitivities of computationally simulated response of soil-foundation-structure systems are needed in:

– Structural Reliability Analysis

– Structural Optimization

– Structural Identification

– Finite Element Model Updating

– Structural Health Monitoring


Application Example of Sensitivity Analysis

F.E. Model of Moment-Resisting Frame Moment-Curvature Constitutive Model

• 1-D J2 (von Mises) plasticity model with linear kinematic hardening and zero isotropic hardening

T1 = 0.52 sec

8 m

( ) ×gu t = 3 El Centro 1940&&


Joint C (column)

Nonlinear Earthquake Response

Mom

ent

[N-m

]M

omen

t [N

-m]

Mom

ent

[N-m

]

Mom

ent

[N-m

]M

omen

t [N

-m]

Joint B (column)

Joint A (column)

Joint C (beam)

Joint B (beam)


Nonlinear Earthquake ResponseSensitivity

Time [sec]Time [sec]

∂ ∂ro

ofy

y

uM

[m

]M

Sensitivity of Roof Displacement to My Zoom

Zoom


Current & Future Research Developments

• Data structures for parameterization of structural models in OpenSees for automatic sensitivity analysis and random variable modeling of material and geometric properties.

• Exact finite element response sensitivity algorithms for generalized plasticity-based structural elements.

• Efficient stochastic modeling of earthquake ground motions.

• Time-variant reliability methods to analyze the propagation of uncertainties (earthquake loading and system parameters) through nonlinear dynamic finite element models of structural systems.


A Platform for Inelastic Structural Analysisof 2D Systems (PISA2D)*

A A PPlatform forlatform for IInelastic nelastic SStructural tructural AAnalysisnalysisof of 2D2D Systems Systems (PISA2D)(PISA2D)**

**K.C. Tsai and LiuK.C. Tsai and Liu--Chuan Chang, EChuan Chang, E--mail: mail: kctsaikctsai@@cece..ntuntu..eduedu..twtw

Dept. of Civil Engineering, National Taiwan UniversityDept. of Civil Engineering, National Taiwan University

l Use Object-Oriented Program and Windowsl Facilitate the interface with substructure

pseudo-dynamic test software: C++ languagel Graphic visualization program (VISA2D):

Visual Basic languagel Nonlinear static and dynamic analysesl A total of 9 elements, three yielding rules

Element Contents in PISA2DElement Contents in PISA2D

l Three yielding rules : l bilinear rulel two surfaces rulel 3 parameters degrading rule

l Three types : l beam (beam-column) elementl truss element l joint element

••**K.C. Tsai and LiuK.C. Tsai and Liu--Chuan Chang, EChuan Chang, E--mail: mail: kctsaikctsai@@cece..ntuntu..eduedu..twtw

•• Dept. of Civil Engineering, National Taiwan UniversityDept. of Civil Engineering, National Taiwan University

Geotechnical Applications Using OpenSees

1. Modeling of saturated soil domain

Several 2D/3D solid elements are available for handling undrained (nearly incompressible) soil domain : enhanced quad, constant pressure/volume quad, B-Bar brick.

2. Simulation of soil liquefaction

Advanced 3D soil material models are available for liquefaction simulations : Manzari, PressureDependMultiYield, FluidSolidPorousMaterial.

3. Modeling of Soil-Structure Interaction

Soil-structure interface behavior can be simulated using zeroLength element combined with various uniaxial materials.

Zhaohui Yang ([email protected]) & Ahmed Elgamal ([email protected]),

UC San Diego

Development of New Geotechnical Capabilities in OpenSees

A general framework for modeling soil as a multi-phase (fluid and solid) domain is currently under consideration.

• Various formulations may be considered : U-u-p, U-w-p, U-p(U = solid displacement, u = fluid displacement, w = fluid displacement relative to solid, p = fluid pressure).

• Different integration and solution methods may be applied to each phase.

• Simplifications may be allowed for specific applications,such as dynamic undrained, quasi-static drained (consolidation), static drained, and static undrained problems.

Zhaohui Yang ([email protected]) & Ahmed Elgamal ([email protected]),

UC San Diego

OpenSees Developer's Workshop

ü Template Elastic-Plastic Framework

ü 3D Brick element

Research topics:

Zhaohui YangUC Davis

Email: [email protected]


ü 3D Static and dynamic soil-pile-structure interaction analysis ü Parallel computing using OpenSees

Zhaohui Yang, UC Davis [email protected]

Cenk Tort, Graduate Research AssistantDepartment of Civil Engineering, 500 Pillsbury Drive SEUniversity of Minnesota, Minneapolis, Minnesota 55455(612) 626-8763, [email protected]: Jerome F. Hajjar, Associate Professor

Research Objectives and Relation to OpenSeesat the University of Minnesota

• Development of 3D static and transient dynamic analysis formulations for composite braced and unbraced frames consisting of steel I-girders framing into rectangular concrete-filled steel tube (CFT) beam-columns

– Implement formulation for CFT fiber element including interlayer slip– Develop CFT connection elements– Implement several cyclic constitutive laws for steel, concrete, and connection components

• Assessment of seismic demand in composite CFT braced and unbraced frames through comprehensive parametric studies using nonlinear transient dynamic analyses

– Run multiple analyses through large-scale batch processing using a suite of ground motions

• Development of a reliability-based performance-based design methodology for composite systems, with a focus on composite CFT structures

– Develop and implement new, integral measures for local and global demand and capacity appropriate for composite structures

– Postprocess results to calculate appropriate statistical quantities over range of parametric studies

Imbsen & Associates, Inc.A Bridge Engineering Consultant Firm, mainly on seismic retrofitdesign for bridges, seismic response analysis, development of computer software relating the design and analysis of bridge structures.

Contact information:Yihua Huang, Ph.D.E-mail: [email protected]: (916)366-0632 (ext. 56)Fax: (916)366-1501

What we are going to use OpenSees forImbsen & Associates, Inc.

I IA

1. Nonlinear static analysis for bridge structures2. Nonlinear dynamic time history response analysis

for bridge structures 3. Response spectrum analysis for bridges with nonlinear

characteristics4. Simulation of earthquake response for a bridge structure5. Prediction of damage due to an earthquake through a

bridge structure

Analysis types:

Special devices in the structure:

1. Energy dissipation devices with material nonlinear characteristics 2. Members with large plastic deformation3. Simulation of isolator bearings in a bridge structure

What we are going to use OpenSees for Bridge Engineering

Yihua Huang, Imbsen & Associates, Inc. ([email protected]) I IA

Advanced R/C bridge modeling in OpenSeesCharley Hamilton, GSR

[email protected], Dept of Civil Engrng, Rm. ELF 139, Irvine, CA 92697-2175

University of California, Irvine

• Nonlinear modeling of bridge system using approximated soil conditions (spring-dashpot boundaries)

• Looking at performance variables (drift, yield, frequency response, etc)

• Developing fragilities based on performance variables (have written own tcl/Tk reliability routines)

• Looking at expanding current plotting tools (recorder plot) to place standard grids in addition to axes– Some sims take > 1hr/ea to complete; visual check desirable

• Advanced concrete material model including strain-rate effects (under development by chamilto)

Laura N. Lowes

University of WashingtonPhone: 206.685.2563

Fax: 206.545.6816E-Mail: [email protected]

WWW: http://www.ce.washington.edu/~lowes

Simulation of RC Beam-Column Joint Response

PPEEEERR

Simulating Component Response: RC Beam-Column Joints

real system

idealized analytical model

beam-columnjoint model

column

column

beam

beam

beam-column

joint

laboratory component test

Drift

Loa

d

Laura N. Lowes, University of Washington ([email protected])

Conceptual Model

Joint Shear Distortion

Join

t She

ar S

tress

Bar

Stre

ss

Bar Slip

column

column

beam

beam

bond-slip springs

interface-shear springs

shear panel


Calibration

Effect of cycling

Observed Response Envelopes

Shear-Panel Action

Simulated Response

Monotonic Envelope

Cyclic Response

shear strain (radians)

shea

r st

ress

(MP

a)

Modified Compression-Field Theory

Monotonic Envelope for Joint Element

0 0.003 0.006 0.009 0.012 0.0150

2

4

6

8

ρ = 0.025

ρ = 0.025



Xiaoyan WuUC Davis

Email: [email protected]

Dynamic Behavior of Coupled System

3D Brick element

Research topics:

OpenSees Developer's WorkshopMultiphysics Formulation and Implementation for OpenSees Platform

Specific Implementation u-p-U

M-- mass matrix. K-- stiffness matrix.C-- damping matrix.U-- total displacement fluid.u--displacement of solid skeleton.p-- pore water pressure.f-- forces.

Xiaoyan Wu, UC Davis ([email protected])

Using OpenSees for Analytical Simulations in Pseudodynamic Testing

ug

displacements

forces

Analytical Model Experimental Model

Gilberto MosquedaDepartment of Civil and Environmental EngineeringUniversity of California, [email protected]

Seismic Evaluation of Prestressed Concrete Bridges

Chyuan-Hwan JengE-mail: [email protected]

Department of Civil and Environmental EngineeringUniversity of Houston

Houston, TX 77204

Contents

•Finite Fiber Element Analysis of Reinforced Concrete Frame Structures

•Object-oriented Programming of FEM Software Using OpenSEES

•Artificial Neural Network

•Summary and Conclusion – Model-based Simulation

Chyuan-Hwan Jeng, University of Houston ([email protected])

Finite Fiber Element Model

• By Euler-Bernoulli Hypothesis (Plane section remains plane) => To determine fibers’ strain from section deformation

• Uniaxial Materials’ Constitutive Laws => To determine fiber stress and tangent modulus from fibers’ strain

• To determine the section forces and section stiffness by adding up all the contribution of each fiber’s stress and tangent modulus .

Section Force-Deformation Relation of A Fiber Section

)()()( xxyxz ziyii εφφε +−=

? y(x)zie(x)

ei


Flexibility-based Finite Fiber Element ModeApplication Example


Flexibility-based Finite Fiber Element ModeApplication Example

Comparison with Experimental Data

Hor

izon

tal L

oad

on C

olum

n T

ip

(kip

s)

-1.0

1.0

-1.2 1.2Horizontal Displacement of Column Tip

(inches)

AnalyticalExperimental


Flexibility-based Finite Fiber Element ModelApplication Example

-0.045-0.040-0.035-0.030-0.025-0.020-0.015-0.010-0.0050.000

Strain

-6000

-5000

-4000

-3000

-2000

-1000

0

Stre

ss( p

si)

-120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120

Displacement (0.01inches)

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

Str

ain

-6000

-5000

-4000

-3000

-2000

-1000

0

Str

ess

(psi

)

Fiber 192: Unconfined Concrete



-0.045-0.040-0.035-0.030-0.025-0.020-0.015-0.010-0.0050.000Strain

-7000.00

-6000.00

-5000.00

-4000.00

-3000.00

-2000.00

-1000.00

0.00

Stre

s s(p

si)

-120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120


-0.060

-0.040

-0.020

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

Str

ain

-7000

-6000

-5000

-4000

-3000

-2000

-1000

0

Str

ess

(psi

)

Fiber 12: Confined Concrete



-0.140 0.000 0.140

Strain

-100000

0

100000

Str

ess

(psi

)

-120 0 120


-0.14

0.00

0.14

Str

ain

-100000

0

100000

Str

ess

(psi

)

Fiber 286: #3 Rebar, Fy = 64.9 ksi


The Application of OOP to FEM ProgrammingConfiguration of An OO FEM Software

Domain

Analysis

ConstraintHandler Algorithm Integrator SystemOfEqnAnalysisModel

FE_Element DOF_Group

DOF_NumbererCreate

Mapping

Some Other ObjectsMaterial Objects: UniaxialMaterial (Concrete, Steel), SectionForceDeformation(ElasticSection, FiberSection)

Numerical Objects:

SOESolver, Matrix, Vector

Recorder Objects:

ElementRecorder, NodeRecorder


The Application of OOP to FEM ProgrammingExample Coding of OO FEM Program

void main(void){

//create a domain Domain *theDomain = new Domain(theStorage);

// create the nodes and add them to the domain// Node(tag, ndof, crd1, crd2, crd3)Node *node1 = new Node(1, 6, 0.0, 0.0, 0.0);Node *node2 = new Node(2, 6, 20.25, 0.0, 0.0);theDomain->addNode(node1);theDomain->addNode(node2);

// create material and fibersFiber *fibersSect1[294]; // array of pointers to fibers for section type 1…….// create the beam-ccolumn element by calling the function:NLBeamColumn3d *elem = createTheElement(fibersSect1, fibersSect2);// and then add them to the domaintheDomain->addElement(elem);

// create the constraint objects and then add them to the domain// SP_Constraint(tag, nodeTag, dofID, value)SP_Constraint *colBaseSp1 = new SP_Constraint(1, 1, 0, 0.0);SP_Constraint *colBaseSp2 = new SP_Constraint(2, 1, 1, 0.0);…..

// create concrete and steel material// tag, fpc, eco, fpcu, ecuConcrete01 unconfinedConc(1, -5300.0, -0.002, -1060.0, -0.0119);Concrete01 confinedConc1(2, -6530.0, -0.00246, -1306.0, -0.3710);Concrete01 confinedConc2(3, -6110.0, -0.00231, -1222.0, -0.2330);// tag, fy, E0, sh ratio, ecuSteel01 steel1(1, 64900., 29000000., 0.0067, -0.16, 0.16);Steel01 steel2(2, 64400., 29000000., 0.0038, -0.20, 0.20);Steel01 steel3(3, 73100., 29000000., 0.0050, -0.164, 0.164);


The Application of OOP to FEM ProgrammingExample Coding of OO FEM Program

// construct a constant nodal loadVector loadVec1(6);loadVec1(0) = -10000.0; // 10 kipsNodalLoad *axialForce = new NodalLoad(10, 2, loadVec1, true);

// construct a load pattern, set it's TimeSeries, and then add it to the domainLoadPattern *theLoadPattern = new LoadPattern(loadPatternTag);theLoadPattern->setTimeSeries(theSeries);theLoadPattern->addSP_Constraint(varyDispl);theLoadPattern->addNodalLoad(axialForce);theDomain->addLoadPattern(theLoadPattern);

// create an Analysis object to perform a static analysis of the modelAnalysisModel *theModel = new AnalysisModel();StaticIntegrator *theIntegrator = new LoadPath( &theLoadPath, .01, 1, 0.0001,100);ConstraintHandler *theHandler = new PlainHandler();EquiSolnAlgo *theSolnAlgo = new NewtonRaphson((*theTest));DOF_Numberer *theNumberer = new PlainNumberer();LinearSOE *theSOE = new FullGenLinSOE(*theSolver);

StaticAnalysis theAnalysis(*theDomain, *theHandler, *theNumberer, *theModel,*theSolnAlgo, *theSOE, *theIntegrator);

// perform the analysis int result = theAnalysis.analyze(numSteps);

}


Some features of artificial neural

networks

• Learning by examples• Self Learning• Adaptivity• Fault tolerance

What can artificial neural

networks be used for?

• Prediction• Classification• Data Association• Pattern Recognition• Data Filtering• Optimization

Artificial Neural NetworkFeatures and Functions of ANNs

PlannedFuture Applications

• Response Simulation• Damage Diagnosis


Summary and Conclusion – MBSModel-Based Simulation

Computing Design Method

1950’s Slide rule Trial and error

1960-70’s Mainframe Simplified analysis with member check

1980’s PC & Workstation Can do some system demonstration and performance verification for the first time

1990’s PC & Internet Can do some integrated system analysis and design , and life-cycle performance-based design has gained increasing popularity

Future??=>Internet Computing Computer simulation has now joined theory and experimentation as a third path to scientific knowledge.

*The objective of MBS proposed by NSF is to replicate the behavior of a complex system under loading and environmental condition.

*The future direction of research must be in the area of modeling (science) , simulation (computing), and validation (experiment).


Summary and Conclusion – MBSManifestation of Model-Based Simulation

• Mathematical Modeling: refined constitutive theory of RC materials is used to rationally account for the behavior of the materials subjected to reversed loading condition.

• Solution Algorithm: a flexibility-based non-linear fiber FEM analysis is used to simulate the overall true behavior of RC frame structures subjected to earthquake excitation. ANN will be employed to provide a larger-scaled quick simulation.

• Software Engineering: an object-oriented programming framework is adopted to enhance software productivity, portability, and general quality.

Conclusion => This research can be viewed as a miniature manifestation of MBS, and is hopefully toward the future of the mainstream research of structural engineering.

3 Steps of the development of MBS for any civil engineering facilities:


L

L

H

Ig

Igcol

beam

Hcol col

beam

beam

beamLo

Locol

Effects of Local Deformations on the Seismic Response of Bridge Structures

Silvia Mazzoni, Gregory L. Fenves([email protected])

Earthquake Engineering Research CenterUniversity of California, Berkeley

ug..

ROTATION DUE TO BAR ELONGATION

bondstress

longitudinalstress

longitudinalstrain

bar

bar

Rotation

Mom

ent

(My,Θy)

(Mn, Θn)(Mu, Θu)

“Strong” bond model:

q e.30 f’c

q p .15 f’c

“Weak” bond model:

q e.15 f’c

q p.6 f’c

“Elastic”

Rotation

Mom

ent

“Rigid”

Mu

Mn

My

Silvia Mazzoni, UC Berkeley ([email protected])

EFFECTS OF JOINT DEFORMATIONS

γ

τ(psi)

5 f’c

7.5 f’c

15 f’c

“Elastic”“Rigid”

“Weak”

“Strong”

3.5 f’c

Rotation

Mom

ent

(My,Θy)

(Mn,Θn)(Mu,Θu)

γ τ

Silvia Mazzoni, UC Berkeley ([email protected])

• Finite element formulation and implementation for inelastic behavior of solids (soils, concrete, rocks...)

• Parallel processing (Beowulf clusters, see http://sokocalo.engr.ucdavis.edu/~jeremic/GeoWulf

• Template (a) Elastic--Plastic computations and (b) Finite Element technology

• Multiphysics (fully coupled solid--fluid formulation andimplementation for example)

• Visualization

Boris JeremicDepartment of Civil and Environmental Engineering

University of California, Davis, 95616 [email protected] http://sokocalo.engr.ucdavis.edu/~jeremic

Research interests related to OpenSees

Boris Jeremic, UC Davis ([email protected])

Research Interests with OpenSeesMichael H. Scott, UC Berkeley

[email protected]• Continue to develop and maintain hierarchical and modular

interface for material models using software design patterns

• Implement response sensitivity algorithms for force-based beam-column elements

• Develop general methodology for identifying and updating model parameters for sensitivity analysis and computational reliability

• Explore algorithms and solution strategies for performing computational reliability on a parallel computing platform

Beam-column connection element

• Graduate researcher: Arash Altoontash• Contact email: [email protected]• Host institution: Stanford university• Academic supervisor: Professor Gregory Deierlein• Objective: Develop a time and cost

effective analytical model for R/C beam-column connections and implement it as an element in OpenSees

column

column

beam

beam

Bond-Slip

Springs

Shear Springs

shear panel

Connection element for R/C frames

Simple Connection element

Arash Altoontash, Stanford University ([email protected])

Fragility of Partially Restrained & Damped Ductile

Connections

Advisors: Reginald DesRoches

Bruce R. Ellingwood

Berk TAFTALIDepartment of Civil & Environmental EngineeringGeorgia Institute of [email protected]

Research Objectives

§ Perform Deterministic & Probabilistic Seismic Demand Analysis

§ Develop an analytical model to represent hysteretic (cyclical) behavior of a class of steel connections.

§Partially Restrained Connections

§Damped Ductile Connections (Shape Memory Alloys)

Our research objectives:

Berk Taftali, Georgia Tech ([email protected])

OpenSees

§ Being able to run parametric studies automatically by

- varying several structural parameters

- running a suite of ground motions

What we expect from OpenSees?

§ Successful representation of the hysteretic behavior by considering - stiffness degradation- strength degradation- fracture

Berk Taftali, Georgia Tech ([email protected])

[email protected]

Pedro Arduino, U of Washington ([email protected])

Motivation, Concepts

Future Work

Structural Reliability Analysis in OpenSeesTERJE HAUKAAS, Ph.D. Student, UC Berkeley, Email: [email protected]

Current Status

• Allow random load, material and geometery parameters in OpenSees.• Compute failure probability estimates. “Failure” is defined in terms of limit-state functions.• Evaluating probability integrals; addressing the PEER framing equation:

• Important aspect of structural reliability analysis: parameter sensitivity and importance measures.

∫ ∫=im dm

?(im)G(dm|im) dG(dv|dm) d ?(dv) ∫=≤0)(

)(x

xxg

f dfp

• Structural reliability analysis is enabled in OpenSees. • FORM, SORM, importance sampling simulation analysis, systems reliability analysis. • Response sensitivity analysis by the direct differentiation method (DDM) is enabled in OpenSees.

Examples & more info: http://www.ce.berkeley.edu/~haukaas

• Further implementations of reliability options and DDM response sensitivity analysis. • Reliability analysis for degrading structural systems.

OSP – OpenSEES Post-Processor

• View animated time history analysis in 3D at any orientation.

• Create .avi files for export to other media.

• View animated modes of vibration quickly and easily.

• Edit OpenSEES input files and immediately see the updated model. Run analysis from within the interface.

Charles Chadwell, UC Berkeley [email protected]

Input File Editor

• Edit source files directly and instantly see the changes graphically

• View variables and Run OpenSEES both from within the editor.

Charles Chadwell, UC Berkeley ([email protected])

Material Tester and Viewer

• View the response of any material model within the OpenSEES source files.


Portability of Nonlinear Sections

Import to OpenSEES, analyze, and use OPS to see the real time hysteretic response.

• 2,345 concrete fibers

• 336 Reinforcing Bars

Use UCFyber to generate the section


Graphical Flexibility

• View any data that is recorded from the OpenSEES analysis.

• View time history or push over traces of Elements, Nodes, and Sections.

• View any part of the structure in any orientation statically and dynamically.


An Application of OpenSees and OSP

The Ji-Lu Cable Stayed Bridge – Taiwan

• Low level material models create unique force deformation elements

• The corotational element and large nonlinear geometry

• Portability from other research programs


Model

The Power of Material ModelsThe Ji-Lu Cable Stayed Bridge - Taiwan

OpenSEES allows material models built from any series or parallel set of other material models. OSP gives the graphical representation

Reality


Research Interest:

1) Modeling Cyclic Response ofRC Elements(with emphasize on shear response)

2) Structural Reliability

Mehrdad SasaniDepartment of Civil Engineering

Northeastern [email protected]

Afsin SARITASAfsin SARITASGraduate Student

Structural Engineering Mechanics and MaterialsDept. of Civil and Environmental Engineering

University of California, Berkeley

Ph.D. AdvisorPh.D. AdvisorProf. Filip C. FILIPPOU

Research InterestResearch InterestNonlinear Analysis of Structures

[email protected]

Improvement of Opensees’s Pre- and Post-ProcessingUsing GiD

Changho Choi [email protected] of Washington

Pre-Processor Post-Processor

Gravity Load Collapse of Reinforced Concrete Frames

Kenneth J. ElwoodPI: Jack P. Moehle

Pacific Earthquake Engineering Research CenterUniversity of California, Berkeley

[email protected]

OpenSees Developers Workshop

August 21-23, 2001Richmond, CA

Analytical Modelfor Shear-Critical Columns

sw

Beam-Column Element

M

θ

Shear-failure limit state surface

V

γ

P

∆vert

P

∆horz

Axial-failure limit state surface

Implemented in OpenSees (almost)

Shear and Axial

LimitState Uniaxial

Materials

(Aggregate) +

Kenneth J. Elwood, UC Berkeley ([email protected])

Coupling of Axial and Shear

sw

=

γ

∆vert

V

P

V

γ

P

∆vert

V

∆vert

?

P

γ ??

Kenneth J. Elwood, UC Berkeley ([email protected])

Macroscopic Modeling forNonlinear Analysis of

Reinforced Concrete Structural Walls

Kutay OrakcalDepartment of Civil and Environmental EngineeringUniversity of California, Los AngelesUCLA, 5731 Boelter Hall, PO BOX 951593, Los Angeles, CA 90095-1593(310) [email protected]

Top Displacement

Lat

eral

Lo

ad

• Investigating a reliable model for practical analysis of reinforced concrete or steel section reinforced concrete structural walls; analytical modeling studies for predicting the inelastic wall response

• Calibration of the model with experimental data from cyclic tests on RC and SRC structural walls

Multi-Component-in-Parallel Model [MCPM](Vulcano, Bertero and Colotti, 1990)

RC Wall Model

h

12

3

45

6

k1 k2 knkH. . . . . . .

-4 -2 0 2 4Top Displacement (in.)

-40

-20

0

20

40

Lat

eral

Loa

d (k

ips)

Quasi-StaticPushover

-2.8 -1.4 0.0 1.4 2.8Lateral Drift (%)

σ

ε

Concrete

σ

εSteel

• Wall flexural capacity and cyclic response captured by the model with reasonable accuracy.• Provides a flexible basis to implement various constitutive relations and calibration with test results.• Improving the shear response and coupling shearstiffness with flexural ductility.• Implementation of the model into [OPENSEES]

Kutay Orakcal, UCLA ([email protected])

Documents

Developer’s Workshop 21-23 August 2001opensees.berkeley.edu/.../Aug2001/ParticipantPresentation.pdfParticipant Presentation of Research Interests using OpenSees •Charley Hamilton,