User Manual
Contents
1. ssssccceeeesscccccceeeeecessseesssssceececnesscccceceeeeeeees 5 Droure o Selection Materials ancii ie aiii 6 Figure 7 Properties of Material in OpenSees2DPS occcccccnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnononnnnnnnnos 7 Figure 8 Properties of Material during application of gravity oooccccccccnnnnnnnnnnnnnnnnnnnnnnnnnnnnnss 7 PICU Sclecion or Analysis MMM A 8 Figure 10 Selection of Earthquake and format of user defined input motion 9 P1eure 11 Selection or Damping Costado 9 Figure 12 Three different types of Boundary Conditions sess 10 Figure 13 Vertical and lateral stress values and stress contour along the depth 11 Monte 15 BEST tree Mode Sape setool E UII SE ERE RUE 11 II 1 INTRODUCTION 1 1 Overview OpenSees2DPS is a PC based graphical user interface designed to perform two dimensional 2D Plane Strain Analysis of earth dam OpenSees an open source framework developed by the Pacific Earthquake Engineering Research PEER Center 1s employed as the Finite Element FE analysis engine http opensees berkeley edu The OpenSees2DPS user interface pre and post processor focuses on facilitating 2D plane strain analysis with additional capabilities yet under development Current version of OpenSees2DPS allows for e Generating 2D geometries and configurations of interest e Modification of linear elastic material and multi yield su2. Y denotes the vertical direction EA AA A NNNNA a b Figure 1 Coordinate system employed in OpenSees2DPS a shear beam and b earth dam 1 4 Installation Requirement OpenSees2DPS executable for PC compatible systems Windows XP Vista or 7 1s written in MATLAB Before using OpenSees2DPS the Tcl Tk and MCR MATLAB Compiler Runtime need to be installed Please visit http opensees berkeley edu OpenSees user download php to download Tcl tk 8 5 MCR can be found in the Help folder provided along with the program After installation of Tcl Tk reboot is needed for the changes to take effect Please reference the default input values for how the values should be entered into the OpenSees2DPS interface OpenSees2DPS user manual 1s available in the folder titled Help 2 GETTING STARTED The interface will allow the user to prepare and save an input file to run the analysis and to display the response The model input window controls geometry of the model material properties analysis types and boundary conditions Figure 2 e Step 1 Mesh Generation geometry of the mesh will be defined in this step e Step 2 Select Material amp Define the Material Properties material properties used in the mesh domain are defined here e Step 3 Select Analysis Option analysis types gravity analysis mode shape analysis or ground shaking can be selected here e Step 4 Execute FE Analysis to save and execute of the finite element a
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4. Shape Number of Modes 3 C Earthquake Analysis El Centro 1940 2 columns time amp a g Scale Factor 1 Nonlinear Rayleigh Dampin Figure 9 Selection of Analysis Type All materials are prescribed as linear during the application of gravity and the mode shape analysis For earthquake analysis there is an option to conduct nonlinear soil computations if the Nonlinear check box if selected Figure 10 For nonlinear analysis soil properties pressure dependent material and pressure independent material are changed to nonlinear status upon the application gravity Only when nonlinear option is selected will the nonlinear parameters such as cohesion peak shear strain etc take effect By clicking Rayleigh Damping button the viscous damping characteristics of the model Figure 11 can be modified by specifying two frequencies f and f must be between 0 1 and 50 Hz and two damping ratios suggested values are between 0 2 and 20 OpenSees2DPS employs the Newmark time integration procedure with two user defined coefficients B and y Newmark 1959 Chopra 2004 Standard approaches may be adopted by appropriate specification of these constants Default values in OpenSees2DPS are y 0 6 and B y voy 4 Bj elcentro txt Notep ad El Centro 1940 2 columns time amp a g EI Centro 1940 30E 03 64E 03 90E 04 28E 03 58E 03 09E 02 B2E 03 E 03 28E 03 68E 03 64E 03 36E 0
5. 2 2 E 03 40E 04 20E 03 21E 03 0E 04 44E 03 b E 03 Erzincan Station Erzincan 1992 U Shake HHH cn ds me Coc I NJ UJ CO C IS NU NJ CO CP s h Earthquake Analysis El Centro 1940 f 4 cloumns time amp a 9 Scale Factor 1 Nonlinear l 202 2255 205 SS cC A a NIN i Soo Figure 11 Selection of Damping Coefficients 2 1 5 Boundary Conditions Three types of boundary conditions are available Figure 12 1 Shear beam The lateral mesh borders undergo shear beam type motions equal motion of lateral boundaries 1s enforced 2 Rigid box The lateral mesh borders is fixed horizontally during application of own weight and fixed in both DOFs thereafter 3 Fixed at the bottom and free lateral boundary w o own weight Boundary Type Shear beam C Rigid box w own weight C Fixed at base amp free lateral boudary w o own weight Figure 12 Three different types of Boundary Conditions To run the analysis click the Run button at the bottom of the interface or click Run Analysis in Menu Execute Upon the user requests to run the analysis OpenSees2DPS will check all the entries defined by the user to make sure the model 1s valid Graphical output will be stored in a folder named by user upon completion of the analysis 2 2 Output Results of stress values due to gravity stress contour due to gravity deformed mesh due to gravity mode shapes and time historie
6. University of California San Diego Department of Structural Engineering OpenSees2DPS Beta 0 1 2D Plane Strain Analysis User Manual Draft B D i v i sf e t r i E i f B P B B B r 4 B E p f y kd f o f y r d e e d y Pe B r s e lt f gt a AN pu y e AR My we fh i R l A A a AN l SS VA 7 Qe du Aa c ye Sedes gt P Wy ay J ap YA SAM ome wre T uL NT MESA b Faye Wey Any oe JA A Va Nw ny E wal sow WI CAG av rad Qe IS hee M e pe IIA N y M A 2 n Aver o DR y S A My d VEI rn e tr S VOCE Rn IANA ws LIPTON An Die y i RUS m AA Pas d 4 V Vo a we d we U d e f d 0 a z A Ar v Mer ALME e WHA LAA a e Panel Sy Was Ny Sie ho Meee ee att Mutha et ea OS E d ON Ke aa 4 f Wu SEN D bu dore M LA DAP Pe SECURUM D bm DA AT AK ie rele Wie webs PA ers Pin Yo 2d 4 i ME A Wa hes Prk A e Ac Nein MOR rN AM Ns e DN str A y Mur DEPARA a TP wae Vier w i ee ey LIP hal pu n be Pee i rA pare e PIN a 1 Vet IRI A m F PEA g M irig e A as LEA 4 4 Aet d Un dn e wr y b Fd cs E Pare Ms neq Ld Y A ves RS UM MAS Y m Aen dea w p wor Ja xA A Oe ter of Y t als Pest A NM WT Ur fom j p wen Mm TE M yt e e en A wl n vv 149 Mou O Phro d i AA eT nes LO that RA
7. ault values which are the same as the values when the program starts up Open Ctrl O option allows the user to open a previously saved model and modify the inputs the model file must have an extension of mat Save Ctrl S option will save the current status of the program under a user defined folder A warning message will pop up if a fold with the given name already exists The current file name is shown above the mesh without extension e Controls of running analyses displaying analysis results or reference to user manual are organized into the Execute Ctrl R Display and Help menu Execute Ctrl R option allows user to save the current input under the desired path and perform the FE analysis When the simulation completes a message box will pop up Display option allows the user to view the stress values stress contour deformed mesh mode shapes and time histories depending on the type of analysis chosen Help option provides general information about OpenSees2DPS and a link to the User Manual lt A mesh oui eee File Execute Display Help File Execute Display Help 3 v d Stress Values Vertical Stress Contour Horizontal Stress Contour Mesh F Deformed Mest Mode Shapes File Execute Display Help Hom sere is Run Analysis Ctrl R Close Figures Ctri4F File Execute Display Help D W pa RQ User Manual About Figure 3 OpenSees2DPS Menu and Submenu Bars 2 1 2 Geometry Defi
8. e systems J Appl Mech ASME 34 612 617 Kondner R L 1963 Hyperbolic stress strain response Cohesive soils Journal of the Soil Mechanics and Foundations Division 89 SM1 115 143 Lu J Yang Z and Elgamal A 2010 OpenseesPL three dimensional lateral pile ground interaction User s Manual Dept of Structural Engineering Univ of California San Diego Mazzoni S McKenna F and Fenves G L 2006 Open system for earthquake engineering simulation user manual Pacific Earthquake Engineering Research Center University of California Berkeley http opensees berkeley edu OpenSees manuals usermanual Mroz Z 1967 On the description of anisotropic work hardening Journal of Mechanics and Physics of Solids 15 163 175 Parra E 1996 Numerical modeling of liquefaction and lateral ground deformation including cyclic mobility and dilation response in soil systems PhD Thesis Department of Civil Engineering Rensselaer Polytechnic Institute Troy NY Prevost J H 1985 A simple plasticity theory for frictional cohesionless soils Soil Dynamics and Earthquake Engineering 4 1 9 17 Yang Z 2000 Numerical modeling of earthquake site response including dilation and liquefaction PhD Thesis Department of Civil Engineering and Engineering Mechanics Columbia University New York NY Yang Z Elgamal A and Parra E 2003 A computational model for cyclic mobility and associated shear d
9. eformation Journal of Geotechnical and Geoenvironmental Engineering 129 12 1119 1127 12
10. linear hysteretic material Parra 1996 Yang 2000 Yang et al 2003 with a Von Mises multi surface Iwan 1967 Mroz 1967 kinematic plasticity model In this regard focus is on reproduction of the soil hysteretic elasto plastic shear response including permanent deformation In this material plasticity is exhibited only in the deviatoric stress strain response The volumetric stress strain response is linear elastic and is independent of the deviatoric response This constitutive model simulates monotonic or cyclic response of materials whose shear behavior is insensitive to the confinement change Plasticity is formulated based on the multi surface nested surfaces concept with an associative flow rule according to the well known Provost approach In the clay model the nonlinear shear stress strain back bone curve is represented by the hyperbolic relation Kondner 1963 defined by the two material constants low strain shear modulus and ultimate shear strength Lu et al 2010 http cyclic ucsd edu openseespl e and Pressure dependent material sand In OpenSees the soil model for cohesionless soils is developed within the framework of multi yield surface plasticity e g Prevost 1985 In this model emphasis is placed on controlling the magnitude of cycle by cycle permanent shear strain accumulation in clean medium to dense sands Parra 1996 Yang 2000 Yang et al 2003 Furthermore appropriate loading unloading flow rules were devi
11. nalysis In this chapter basic features of OpenSees2DPS such as menus and dialogs will be introduced 2 1 Interface There are 3 main regions in the OpenSees2DPS window menu bar the model input area and the finite element mesh area Figure 2 In addition there are six tool bars available to manipulate the mesh Print Pan Data Cursor Zoom in out and Rotate OpenSees2PS lo xi File Execute Display Help a a Y pa WN 9 Mesh Parameters Untitled Horizontal of Element 1 Vertical of Element 10 20 Width at the top m 1 Width at the bottom m 1 Element Height m 2 15 Apply Material f Elastic Material M Gravity Soil Properties during Gra Phase Analysis Type 10 C Own Weight Mode Shape Number of Modes 3 C Earthquake Analysis 4940 2columns time amp a g E EIC Scale Factor 1 F Nonlinear Rayleigh Damping Boundary Type Shear beam 0 C Rigid box C Fixed at base amp free lateral boudary w o own weight 15 10 5 0 5 Advanced Options Run Figure 2 OpenSees2DPS main window 2 1 1 Menu The menu bar includes File Execute Display and Help 4 parts Figure 3 which offers access to controls of OpenSees2DPS Hotkeys are available for some of options e To save and or open input files for the OpenSees2DPS exe you can use the options under File as shown in Figure 3 New Ctrl N option will load the def
12. nement ratio Ko and Shear Modulus at elastic stage Figure 8 This will reduce initial shear stresses in the mesh due to ownweight application Material 2 Pressure Independent v Gravity soll Properties during Gravity Phase Figure 8 Properties of Material during application of gravity 2 1 4 Analysis types Three types of analysis are available Application of own weight mode shape analysis and earthquake time history analysis Figure 9 For all three cases the bedrock 1s assumed to be rigid When the option Mode Shape is selected the number of desired modes is required This number 1s limited to N 1 where N is the number of inertial DOFs For Earthquake analysis base seismic excitation can be defined by either via a built in input motion library or via a user defined input motion U Shake The U shake motion will allow user to employ any motion from an external file The U shake time history should be formatted with no header line and must consists two columns for time 1 column in second and acceleration 24 column in g as shown in Figure 10 Excitation is prescribed along the mesh base as total dynamic lateral motion and the amplitude of input motion can be scaled by a factor By default this Scale Factor is set to 1 Note that the user defined input motion file must be placed in the subfolder motions This subfolder also contains all provided built in input motion files Analysis Type Own Weight Mode
13. nition The geometry of the finite element mesh 1s defined by the following parameters Figure 4 Horizontal number of Element The number of uniform mesh along X direction The value entered must be an integer greater than zero Width at the top The total width of mesh top The value entered must be greater than zero Width at the bottom The total width of mesh bottom The value entered must be greater than zero Vertical number of Element The number of mesh along Y direction The value entered must be an integer greater than zero Element Height The uniform height of each element in Y direction The value entered must be greater than zero The mesh is displayed on right of the interface window Once all mesh parameters are specified click Apply button in the Mesh Parameters window to update the mesh The mesh can be zoomed in out and moved using tool bars Figure 5 The coordinates of mesh can be retrieved by clicking the data cursor tool bar Mesh Parameters Horizontal of Element 1 Vertical of Element 10 Width at the top m 1 Width at the bottom m 1 Element Height m 2 Apply Figure 4 Definition of meshing parameters 208ARD Figure 5 Tool bar for mesh manipulating 2 1 3 Material Properties In OpenSees2DPS three types of material are available for mesh domain Figure 6 e Elastic material e Pressure independent material clay The pressure independent material is modeled as a non
14. rface soil models Pressure dependent Drucker Prager cone model and pressure independent Mises of J2 soil models are available e Performance of different loading scenarios including own weight analysis eigenvalue analysis and earthquake time history analysis e Generation of OpenSees input file TCL and results from the analysis e Visualization of analysis results stress contours deformed mesh mode shapes with corresponding frequencies and response time histories OpenSees2DPS makes it easy to build a model run FE analysis and evaluate the model response The program allows execution of linear analysis to give users more basic insight before exercising the plasticity based nonlinear soil compatibilities OpenSees2DPS was developed by Ning Wang n9wang ucsd edu Dr Ahmed Elgamal elgamal ucsd edu Dr Jinchi Lu jinlu ucsd edu and Dr Zhaohui Yang yangaaa gmail com The OpenSees geotechnical simulation capabilities were developed by Dr Zhaohui Yang and Dr Ahmed Elgamal For more information please visit http cyclic ucsd edu opensees 1 2 Units The SI unit system 1s used for this program Some commonly used quantities can be converted as follows m 39 37 in kPa 0 14503789 psi 1 kg 0 001 tonnes 1 kN 0 224809 kips 1 3 Coordinate System The global coordinate system employed in OpenSees2DPS is shown Figure 1 The origin is located at the left bottom of the mesh X denotes the horizontal direction while
15. s are ready to view upon the completion of simulation Options are available in Menu Display 3 EXAMPLES 3 1 Verification of Linear Finite Element Analysis Using OpenSees2DPS Geometry of the Model Width 2 m Height 20 m Number of Elements in Horizontal Direction 4 Number of Elements in Vertical Direction 40 Shear Modulus of Elastic Material 80000 kPa Density of Material 2000 kg m Poisson s Ratio 0 4 For linear elastic analysis using OpenSees2DPS the OpenSees2DPS results agree well with the analytical solution for vertical and horizontal stresses Figure 13 where Oy pgh 2X9 81X19 75 387 5 kPa Ox Oy K 387 5 0 4 0 6 258 3 kPa When a valid number for the Mode Shape analysis is give mode shapes along with the frequency in Hz will be plotted Figure 14 where theoretically fi Vs 4H 200 4 20 2 5 Hz and f gt 3 fi 7 5 Hz Acceleration time history agrees well with the 3D analysis using OpenSeesPL Lu et al 2010 10 Figure 13 Vertical and lateral stress values and stress contour along the depth Mode Shape 1 Mode ShapeF 2 Mode Shape F 3 2 4998 f 6 1233 Hz 7 4957 Hz Figure 14 First three Mode Shapes 11 Absolute Acceleration at top 2D Plane Strain 3D OpenSees a m s s o 5 10 15 20 25 30 Time s Figure 15 Absolute acceleration at top References Iwan W D 1967 On a class of models for the yielding behavior of continuous and composit
16. sed to reproduce the observed strong dilation tendency and resulting increase in cyclic shear stiffness and strength Lu et al 2010 http cyclic ucsd edu openseespl Material 1 Elastic Material 1 Elastic Material 2 Pressure Independent 3 Pressure Dependent Figure 6 Selection of Materials Material Mass Density default 2000 kg m Poisson s Ratio default 0 4 and Shear Wave Velocity default 300 m s suggestted 10 6000 m s are required to specify for linear analysis In addition nonlinear properties such as Friction Angle The friction angle at peak shear strength in degrees suggestted value between 5 and 65 degrees for sandy soil PressureDependMulti Yield with confinement dependent shear response Figure 7 Cohesion The apparent cohesion at zero effective confinement suggestted value 0 5000000 kPa for Clay material PressureIndependMultiYield Figure 7 and Peak Shear Stain An octahefral shear strain at which the maximm shear strnegth is reached specified at a refenrece mean effective confining pressure suggestted value between 0 001 and 20 Number of Yield Surfaces is set to be 20 All the nonlinear properties will only take effects when nonlinear analysis option is activated Pressure Inderal Ed aos Figure 7 Properties of Material in OpenSees2DPS When own weight of the material is applied it 1s possible to select different Poisson s Ratio to control the initial lateral vertical confi
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