User`s Manual - Cyclic1D - University of California, San Diego
Contents
1. 7 Friction angle in degrees suggested value between 5 and 65 degrees Shear strength Tmax at any confinement level p is given by Tax C psing 8 Peak shear strain Figure 2 in suggested value between 0 001 and 20 Peak shear strain is defined at p 9 Number of yield surfaces NYS Suggested value is between 0 and 30 Figure 2 In particular NYS 0 dictates an elastic shear response Parameters 6 8 are ignored see Figure 2 NYS 1 indicates an elastic perfectly plastic shear response Parameter 8 is ignored see Figure 2 User Defined Saturated Granular Strata with Pore Pressure Effects Granular strata e g sands gravels and non plastic silts with confinement dependent shear response properties that are susceptible to significant pore pressure variation can be defined by specifying the following parameters Figure 2 1 Permeability coefficient m sec Typical range of values is Gravel Sand Silty Sand Silt Clay gt 1 0x10 1 0x10 1 0x10 1 0x107 1 0x10 1 0x10 1 0x107 lt 1 0x10 2 Mass density in kg m suggested value between 1000 and 3000 kg m 3 Reference mean confinement p in kPa This is the confinement level at which appropriate soil properties below see also Figure 2 are defined 4 Reference shear wave velocity Var in m s suggested value between 10 and 6000m s Vs is defined at the Reference mean confinement p below 132. 4 User defined mass density in kg m suggested values between 1300 and 2500 kg m Other than the rigid base scenario the specified input motion acceleration file is considered to be the incident motion component only As such the program computes the total motion at the specified stratum rock interface i e sum of the incident and reflected waves Incident motion files may sometimes be obtained by 1 Using a recorded rock outcrop acceleration file with the amplitudes scaled to 1 2 of the recorded values assuming essentially the rock outcrop to be Rigid 2 Using an appropriate program that allows de convolution e g the well known program SHAKE Schnabel et al 1972 starting with a rock outcrop motion and computing a within motion at the desired stratum depth make sure to obtain the incident motion component for use in Cyclic1D In this de convolution calculation it is suggested to use an elastic rock model or mildly nonlinear with appropriate damping or 3 which is not recommended starting at the surface with a recorded ground surface acceleration record and attempting to de convolve this motion using SHAKE for instance This approach has been known to be problematic and is not recommended Input Motion Motion Type If Bedrock is assumed Rigid the input motion selected below is total motion If Bedrock is not assumed Rigid input motion is treated as a rock outcrop motion i e a
3. Geotechnical and Geoenvironmental Engineering ASCE 129 12 1119 1127 A Web based Platform for Live Internet Computation of Seismic Ground Response 2004 Z Yang J Lu and A Elgamal Advances in Engineering Software 35 249 259 Earth Dams on Liquefiable Foundation Numerical Prediction of Centrifuge Experiments 2004 Z Yang A Elgamal K Adalier and M Sharp J Engineering Mechanics ASCE 130 10 1168 1176 Dynamic Response of Saturated Dense Sand in Laminated Centrifuge Container 2005 A Elgamal Z Yang T Lai B L Kutter and D Wilson J Geotechnical and Geoenvironmental Engineering ASCE 131 5 598 609 Modeling Soil Liquefaction Hazards for Performance Based Earthquake Engineering 2001 S Kramer and A Elgamal Pacific Earthquake Engineering Research PEER Center Report No 2001 13 Berkeley CA 26
4. 5 Confinement dependence coefficient n Shear wave velocity V varies with confinement p in this form V V p p oe 6 Initial lateral vertical stress ratio also known as the coefficient of lateral earth pressure at rest Ko suggested value between 0 1 and 0 9 In the program Ko is related to Poisson s ratio v by the following relation K v 1 v 7 Cohesion C in kPa suggested value between 10 and 200000 kPa Cohesion is the shear strength at zero confinement 8 Friction angle in degrees suggested value between 5 and 55 degrees Shear strength Tmax at a confinement p is given bY Tmas c psing 9 Peak shear strain Figure 2 in suggested value between 0 001 and 20 Peak shear strain is defined at p 10 Number of yield surfaces NYS Suggested value is between 0 and 30 Figure 2 In particular NYS 0 dictates an elastic material Parameters 7 9 are ignored see Figure 2 NYS 1 indicates an elastic perfectly plastic material parameter 9 is ignored see Figure 2 11 Dilation angle in degrees Dilation angle Elgamal et al 2003 divides the domain of shear induced volume contraction response from that of volume dilation via a Phase Transformation PT surface see Figure 3 To remove contraction behavior completely set this angle to zero To remove dilation behavior completely set this angle larger than the friction angle 12 Below the Phase transformation PT surface Figure 3 a Contraction p
5. Uncheck All i SS J FFT Spectral Amplification of Acc Uncheck All g Y Horizontal Displacement Time History Uncheck All 10 V Excess Pore Pressure Time History Uncheck All S V Shear Stress vs Shear Strain Uncheck All JV Shear Stress vs Effective Confinement Uncheck All Output to file D My Documents Untitled_Results Untitled doc LHS Box Depth Moving RHS Box Buttons Figure 5 Selector for Response History Figures in Report Generator There are two list boxes Figure 5 one referred to as LHS box thereafter is to list all of the depths that ARE NOT in the report The other referred to as RHS box thereafter is to list all of the depths that ARE in the report The user can move a depth between the LHS box and the RHS box with one of the four buttons located between the two list boxes Once the RHS box contains a depth or more the user can select any figures by checking or unchecking corresponding check boxes for a depth selected in the RHS box The button Check All or Uncheck All right next to a response history figure can be used to facilitate a selection Clicking a Check Al button will include the response history figure right next to the button for ALL OF THE DEPTHS IN THE RHS BOX Clicking a Uncheck All button will remove from the report the response history figure right next to the button for ALL OF THE DEPTHS IN THE RHS BOX Note that a Check All button will become a Uncheck All bu
6. convergence tolerance Note An additional fluid phase Chan 1988 time integration parameter 0 is set to 0 6 in the data file N tal Y gt unconditional non stable stability S S conditional stability 00 amra 0 0 0 5 1 0 15 2 0 PB 1 6 y 1 2 Linear acceleration conditionally stable scheme P 1 4 y 1 2 Average acceleration or trapezoidal rule unconditionally stable scheme in linear analyses B 1 12 y 1 2 Fox Goodwin fourth order accurate Figure 4 Newmark Time Integration 17 Running the Analysis To run the analysis click Save Model amp Run Analysis in Menu Analyze or Save Model amp Run Analysis Button at the bottom of the Model Input window Upon the user requests to run the analysis Cyclic1D will check all the entries defined by the user to make sure the model is valid Thereafter a small window will show the progress of the analysis By default graphical output windows will be opened upon completion of the analysis To only verify if the input model is valid choose Check Input Data in Menu Analyze Response at a Location To view the response time histories click View Response Histories in Menu Output The figures show the response histories at different depths Om at ground surface and the largest at the bottom of the soil column Seven types of response time histories are available e Horizontal Acc
7. nt INDU peren A A eh ah ceva aa Aida de Predefined Maternal es da User defined MaterlalS o ooooncnnnncccooniconcccnanoconnncnanocannccnnnocnnn conoce canon cnn no cnnnc can ne cannn cnn ne cana ncannccnns User Defined Clay Rock Strata with No Pore Pressure Effects oooooccinnciononicconcccononoccononconononcononcnnoos User Defined Granular Soil with No Pore Pressure Effects User Defined Saturated Granular Strata with Pore Pressure Effects ADDITIONAL VISCOUS DAMPING eeccececessceeccecescceeseecessceescecessceeseeceasccsseeceasceessecsscesssecsssceeseeesssensaes STEP BY STEP TIME INTEGRATION ccccceccccssccesssecscecesscecssecessvensecesseeessecessevensecesseesssecesseecsaecnssecenaees RUNNING THE ANALYSIS o ciscscccecccscccasesscteocsoascsusscndesvceensesssossebseevetoceedoossesecessoeshuvnscbsocbasoededeastesoseevsssons 18 RESPONSE ATA COCA TONE betes tude eel ai Steeles Aa Bea atric dote det fue ede catalan foe coed 18 RESPONSE PROFILE na std ts nt ido lt Dato cios 19 REPORT GENERATOR ested ite dd Ud td tr Ll o 20 ACKNOWLEDGMENTS visssisisssssccocossessescosesvsiessesssonsessasessossebonsestesessebnesnsdessesessubeesceguavesesbatvesoodessesassesssics 22 REFERENCES vicesscssassiscssessasssscocesssesnnsecssacadetes ened snseescasocuseebsodsessoedenssasdacaocessinaensassbasupedaaenadetevondssesosenseassed 23 APPENDIX CYCLIC1D RELATED REFERENCE G cccsccssssssccosscssssessssscsscesseessesssessecsscsone
8. 55 40 0 4 6 6E 05 2100 ds 255 40 0 4 1 0E 02 2100 permeability Shear wave pntralmca eae Mass shear Poisson s Permeability 246 Cohesive Soil velocity 7 5 density strength ratio coeff m s 3 Soft 100 18 0 0 4 1 0E 09 1300 Medium 200 37 0 0 4 1 0E 09 1500 Stiff 300 75 0 0 4 1 0E 09 1800 10 1 Shear wave velocity of cohesionless soils varies approximately in proportion to pm where pm is effective mean confinement 2 Shear wave velocities for cohesionless soils are based on the empirical formula of Seed and Idriss 1970 3 Friction angles for cohesionless soils are based on Table 7 4 p 425 of Das B M 1983 4 Poisson s ratio is used for calculation of initial lateral confinement Ko 5 Permeability values are based on Figure 7 6 p 210 of Holtz and Kovacs 1981 6 Mass density is based on Table 1 4 p 10 of Das 1995 7 Undrained shear strength for cohesive soils are based on Table 7 5 p 442 of Das 1983 User defined materials There are 30 user defined materials including 10 clay rock materials with properties independent of confinement variation and 10 sandy materials with confinement dependent material properties Some user defined materials do not take into account dynamic pore pressure generation effects Therefore this class of materials is suitable for soil layers that are not susceptible to significant pore pressure variation during earthquake excitation To define the parameters of a
9. E Seismically induced liquefaction and resulting deformations are complex mechanisms Much expertise and sound engineering judgment are necessary in interpreting the Cyclic1D computational results o 2 3512 31 292 qa Deviatoric plane O Principal effective stress space Figure 1 Multi yield surfaces in principal stress space and deviatoric plane after Prevost 1985 Parra 1996 and Yang 2000 Element Input Enter element numbers and or ranges associated with each material separated by commas For example 1 3 4 5 6 8 Element numbering is from the top down i e Element 1 is at the surface Predefined materials There are15 predefined materials Basic model parameter values for these materials are listed below Shear wave ae x Friction a Mass y velocity at 3 Poisson s Permeability a6 Cohesionless Soil 1 12 angle 4 5 density 0m depth ratio coeff m s ks m mila degrees kg m Loose silt permeability 185 29 0 4 1 0E 07 1700 Loose sand permeability 185 29 0 4 6 6E 05 1700 Loose gravel permeability 185 29 0 4 1 0E 02 1700 Medium silt permeability 205 31 5 0 4 1 0E 07 1900 Mediun sane 205 31 5 0 4 6 6E 05 1900 permeability Me gun gravel 205 31 5 0 4 1 0E 02 1900 permeability Medi Cou eeni 225 35 0 4 1 0E 07 2000 permeability iS 225 35 0 4 66E 05 2000 permeability al 225 35 0 4 1 0E 02 2000 permeability Dense silt permeability 255 40 0 4 1 0E 07 2100 Dense sand permeability 2
10. The references for Cyclic1D are Elgamal A Yang Z and Lu J 2006 Cyclic1D A Computer Program for Seismic Ground Response Report No SSRP 06 05 Department of Structural Engineering University of California San Diego La Jolla CA Yang Z Lu J and Elgamal A 2004 A Web Based Platform for Computer Simulation of Seismic Ground Response Advances in Engineering Software 35 5 249 259 Cyclic D Seismic Ground Response Version 1 2 User s Manual Ahmed Elgamal Zhaohui Yang and Jinchi Lu University of California San Diego Department of Structural Engineering January 2010 Table of Contents INTRODUCTION fsiscesscossssocsscscssssctsssecssssstecavssevecdedsusscdsdanaosecdsndeodesdnsoscatosdunbebbboossobscdeasossvoensoessesagudesoasanssesess 3 EXECUTION OF CYCLIC1D HELPFUL HINTS ooooococcccconcconocononoconoconnnoconononnnocononcnnno cono ccoo no connn conce cnnnccnnne cines 4 SYSTEM REQUIREMENTS ccccccssccesscecesccesscecesccesssccseceseecnsecesssecasecesseccssecesevessecesseveasecessevessensseveaeenss 5 INSTALLATION a a e o eee o A e e 5 DEFINITION OF MODEL PROFILE occconoconccnnocnnccnnconcconcconccncconoconoconocnnocnoconoconconnconccon cono cono conoconoss 6 SOM STRATUM cinto techni pes ithe tat atado o el ek Oe e la Bo A E a INPUT MOTION ote csntian tallas derbi dudo llo olle css Dl SOI PROPERTIES 20 E te orar moler Mec da e ele red o Bl e ln UE T MAA ai us riera El em
11. arameter 1 c7 dictates the rate of pore pressure buildup under undrained conditions Recommended range of values is 0 3 0 0 very loose to very dense and b Contraction parameter 2 c2 reflects the effect of overburden pressure on contraction behavior Recommended range of values is 0 2 0 6 very loose to very dense As such the level of excess pore pressure buildup or the decrease in effective confinement due to this contractive response e g phase 0 1 in Figure 3 is dictated by a simple relationship of the form Elgamal et al 2003 c E C E 2 where pa is atmospheric pressure a 13 Above the PT surface Figure 3 a Dilation parameter 1 d7 dictates the rate of volume expansion or reduction of pore pressure Recommended range of values is 0 0 0 6 very loose to very dense and b Dilation parameter 2 d2 reflects the effect of accumulated shear strain on dilation behavior Recommended value is 10 As such the degree of regain in shear stiffness above the PT surface due to this dilative response e g phase 1 2 in Figure 3 is dictated by a simple relationship of the form Elgamal et al 2003 d exp d 7 14 14 Liquefaction parameter dictates the extent of shear strain accumulation e g phases 4 5 and 7 8 in Figure 3 Recommended range of values is 0 025 0 0 very loose to very dense a b Figure 3 Shear effective confinement and shear stress strain response 15 Addi
12. eleration Time History e Response Spectrum of Acceleration shown versus Period e Response Spectrum of Acceleration shown versus Frequency e Fourier Transform Amplitude of Acceleration e Spectral amplification of acceleration relative to base motion e Horizontal Displacement Time History e Excess Pore Pressure Time History e Shear Stress versus Shear Strain e Shear Stress versus Effective Confinement To zoom in or zoom out use mouse to select a window Click fill to get back to the original figure 18 Response Profile To view the response profiles click View Response Profile in Menu Output The figures show response profiles of the model Seven types of response profiles are available e Horizontal Displacement e Horizontal Acceleration e Excess Pore Pressure e Effective Confinement e Shear Strain e Shear Stress To zoom in or zoom out use mouse to select a window Click fill to get back to the original figure 19 Report Generator To get an analysis report in Microsoft Word Document format click Create a MS Word Report in Menu Report The report will include three sections Model Input Response Profile and Response History Model Input If the check box Include all model input parameters is checked the report will include all parameters of model input including model profile input motion soil properties and damping coefficients If not the user can select some of the above f
13. es Definition of Model Profile Soil Stratum Soil Profile Height The Soil Profile Height is in meters Number of Elements The Number of Elements can be chosen between 10 and 2000 Water Table Depth The Water Table Depth refers to the depth below ground surface e g 0 0 corresponds to a fully saturated soil profile 1 0 is 1m below ground surface Dry sites should specify water table depth to be equal to the entire model depth Inclination Angle The Inclination Angle is in degrees Zero degree represents level ground For mildly inclined infinite slopes suggested values are from 0 to 10 degrees Bedrock A rigid base may be specified corresponds to an infinitely rigid rock base In this case the base input excitation is actually the total acceleration occurring at the model base For situations other than the rigid base properties of bedrock are as follows Bedrock type Shear wave velocity m s Mass density kg m Soft Rock 700 2500 Rock 1100 2500 Hard Rock 1600 2500 U Rock User defined User defined User defined 4 1 Shear wave velocities for rocks are based on International Code Council 1998 2000 International Building Code Final Draft 2 There are two options for a user to define own rock one is to use the same properties as the soil column at the bottom element the other is that the properties are defined by the user 3 User defined shear wave velocity in m s suggested values between 100 and 6000
14. es 1 Shear modulus Shear Shear modulus Shear Mass density x strain Mass density x strain Shear wave velocity Shear wave velocity Figure 2 Soil Backbone curve and yield surfaces User Defined Granular Soil with No Pore Pressure Effects Granular Soil e g Sands gravels non plastic silts with confinement dependent shear response not susceptible to significant pore pressure variations can be defined by specifying the following parameters see Figure 2 Note All parameters shown in Figure 2 are defined at the reference mean confinement p 1 Mass density in kg m suggested range of values between 1000 and 3000 kg m 2 Reference mean confinement p in kPa This is the confinement level at which soil appropriate soil properties below see also Figure 2 are defined 12 3 Reference shear wave velocity Vs in m s suggested range between 10 and 6000m s This Vs corresponds to the Reference mean confinement pr 4 Confinement dependence coefficient n Shear wave velocity V varies with confinement p in this form V V p py E 5 Initial lateral vertical stress ratio also known as coefficient of lateral earth pressure at rest Ko suggested value between 0 1 and 0 9 In the program Kois related to Poisson s ratio v by the following relation K v 1 v 6 Cohesion C in kPa suggested value between 10 and 200000 kPa Cohesion is the shear strength at zero confinement Figure 2 at the origin
15. es 25 Introduction Cyclic1D is a nonlinear Finite Element program for one dimensional 1D lateral dynamic site response simulations The program operates in the time domain allowing for linear Hughes 1987 and nonlinear studies Nonlinearity is simulated by incremental plasticity models to allow for modeling permanent deformation and for generation of hysteretic damping For analysis of dry as well as saturated strata the finite elements are defined within a coupled solid fluid u p formulation Chan 1988 Ziekiewicz et al 1990 Dry and or saturated soil profiles may be studied In saturated cohesionless soil strata liquefaction and its effects on ground acceleration and permanent deformation are modeled In this regard the user may wish to explore the response of a level ground site or conversely to investigate the response of a mildly inclined infinite slope site The Microsoft Windows based interface allows for 1 convenient pre processing 1 e preparation of input data file 2 initiation and execution of the computations 3 display of the response output and 4 generation of an output report with the desired figures and relevant information This interface is designed for simplicity and is intended to be intuitive and self explanatory Execution of Cyclic1D Helpful Hints 1 Cyclic1D operates in SI units 2 Start with the simplest possible model of the scenario you wish to study As you gain confidence in the results g
16. gineering ASCE Vol 122 No 1 39 49 January Analyses and Modeling of Site Liquefaction Using Centrifuge Tests 1996 E Parra K Adalier A W Elgamal M Zeghal and A Ragheb Eleventh World Conference on Earthquake Engineering Acapulco Mexico June 23 28 Numerical Modeling of Liquefaction and Lateral Ground Deformation Including Cyclic Mobility and Dilation Response in Soil Systems 1996 Ender Parra PhD Thesis Dept of Civil Engineering Rensselaer Polytechnic Institute Troy NY Identification and Modeling of Earthquake Ground Response II Site Liquefaction 1996 M Zeghal A W Elgamal and E Parra Soil Dynamics and Earthquake Engineering Vol 15 523 547 Elsevier Science Ltd Soil Dilation and Shear Deformations During Liquefaction 1998a A W Elgamal R Dobry E Parra and Z Yang Proc 4th Intl Conf on Case Histories in Geotechnical Engineering S Prakash Ed St Louis MO March 8 15 pp1238 1259 Liquefaction Constitutive Model 1998b A W Elgamal E Parra Z Yang R Dobry and M Zeghal Proc Intl Workshop on The Physics and Mechanics of Soil Liquefaction Lade P Ed Sept 10 11 Baltimore MD Balkema Modeling of Liquefaction Induced Shear Deformations 1999 A Elgamal Z Yang E Parra and R Dobry Second International Conference on Earthquake Geotechnical Engineering Lisbon Portugal 21 25 June Balkema Numerical Modeling of Earthquake Site Response Incl
17. iversity of California Berkeley 23 Yang Z 2000 Numerical Modeling of Earthquake Site Response Including Dilation and Liquefaction Ph D Dissertation Dept of Civil Engineering and Engineering Mechanics Columbia University New York NY Zienkiewicz O C Chan A H C Pastor M Paul D K and Shiomi T 1990 Static and Dynamic Behavior of Soils A Rational Approach to Quantitative Solutions I Fully Saturated Problems Proceedings Royal Society of London A 429 285 309 24 Appendix Cyclici1D Related References Numerical Analysis of Seismically Induced Deformations In Saturated Granular Soil Strata 1994 Ahmed M Ragheb PhD Thesis Dept of Civil Engineering Rensselaer Polytechnic Institute Troy NY Identification and Modeling of Earthquake Ground Response 1995 A W Elgamal M Zeghal and E Parra First International Conference on Earthquake Geotechnical Engineering IS TOKYO 95 Vol 3 1369 1406 Ishihara K Ed Balkema Tokyo Japan Nov 14 16 Invited Theme Lecture Prediction of Seismically Induced Lateral Deformation During Soil Liquefaction 1995 T Abdoun and A W Elgamal Eleventh African Regional Conference on Soil Mechanics and Foundation Engineering International Society for Soil Mechanics and Foundation Engineering Cairo Egypt Dec 11 15 Liquefaction of Reclaimed Island in Kobe Japan 1996 A W Elgamal M Zeghal and E Parra Journal of Geotechnical En
18. nd Ragheb A 2003 Modeling of Cyclic Mobility in Saturated Cohesionless Soils Int J Plasticity 19 6 883 905 Holtz R D and Kovacs W D 1981 An Introduction to Geotechnical Engineering Prentice Hall Englewood Cliffs New Jersey Hughes T 1987 The Finite Element Method Linear Static and Dynamic Finite Element Analysis Prentice Hall Inc 1987 Kramer S L 1996 Geotechnical Earthquake Engineering Prentice Hall Inc Upper Saddle River New Jersey 653 pp Newmark N M 1959 A Method of Computation for Structural Dynamics ASCE Journal of the Engineering Mechanics Division Vol 85 No EM3 1959 Parra E 1996 Numerical Modeling of Liquefaction and lateral Ground Deformation including Cyclic Mobility and Dilative Behavior is Soil Systems PhD Dissertation Department of Civil Engineering Rensselaer polytechnic Institute Try NY Prevost J H 1985 A Simple Plasticity Theory for Frictional Cohesionless Soils Soil Dynamics and Earthquake Engineering 4 1 9 17 Schnabel P B Lysmer J and Seed H B 1972 SHAKE A computer program for earthquake response analysis of horizontally layered sites Report No EERC 72 12 Earthquake Engineering Research Center University of California Berkeley California Seed H B and Idriss I M 1970 Soil moduli and damping factors for dynamic response analyses Report EERC 70 10 Earthquake Engineering Research Center Un
19. our types of model input parameters individually Response Profile If the box Include all response profile figures is checked the report will include all response profile figures including horizontal displacement horizontal acceleration excess pore pressure effective confinement shear strain and shear stress If not the user can select some of the above figures individually Response at a Location By default the check box Include all figures of response at Om depth surface is checked In this case the report will include all seven types of response time histories at the surface Om depth e Horizontal Acceleration Time History e Response Spectrum of Acceleration e Fourier Transform Amplitude of Acceleration versus Frequency e Fourier Transform Amplitude of Acceleration versus Period e Spectral Amplification of Acceleration relative to base motion e Horizontal Displacement Time History e Excess Pore Pressure Time History e Shear Stress versus Shear Strain e Shear Stress versus Effective Confinement 20 If the above check box is unchecked the user can select any response history figure at any depth Figure 5 Depths not in the report Depths to be in the report 0 gt 1 V Horizontal Acceleration Time History Uncheck All A 2 Y Response Spectrum of Acc versus Period Uncheck All 5 lt V Response Spectrum of Acc versus Frequency Uncheck All 6 o Y FFT Amplitude of Acceleration
20. racy i e the higher frequency response is becoming stable and is not changing significantly It is suggested to undertake this step only after you have verified that all modeling parameters are in good order and that the resulting response is logical in order to save time and effort As a guideline for linear analysis the maximum frequency Fmax that an element of shear wave velocity V and height h can transmit is Fmax V h 4 0 3 Make use of the available help buttons in the Windows Interface for additional clarifications System Requirements Cyclic1D runs on PC compatible systems using either Windows 98 Windows NT V4 0 Windows 2000 or Windows XP The system should have a minimum hardware configuration appropriate to the particular operating system Internet Explorer 3 0 or above or compatible Browser with Java Applet enabled is needed to view the graphic results For best results your system s video should be set to 1024 by 768 or higher Installation After downloading the Cyclic1D installation file double click on the icon and the installation procedure will start Once installed the default case in Cyclic1D is a good way to go through the steps involved in conducting a Cyclic1D analysis The interface will allow the user to prepare and save an input file to run the analysis and to display the response A Report Generator facility allows users to save all or selected input parameters and response figur
21. radually proceed towards more elaborate simulations If you are a new user consider running a simple case using one of the U clay rock models and specify Linear run Under an earthquake excitation with rigid base specified you should observe the fundamental resonance at the frequency of f Vy 4H8 in Hz where V is the shear wave velocity and H is the stratum height for example try perhaps a V 200 m sec and H 50 m with 50 elements for example and check figures of Spectral amplification of acceleration relative to base motion In this simple case higher resonances should appear at 3f 5 f 7 f and so forth Note that these resonant responses will become more pronounced as you reduce the specified viscous damping The actual numerical resonant frequencies should approach the above theoretical values as the specified number of elements modeling the stratum increases and as the base excitation file time step decreases and also as the duration of base excitation increases see Chopra 2000 For shear beam resonance see Elgamal 1991 3 The smaller the element height the higher the frequency content that the model is able to simulate For traditional site response calculations seismic excitation is usually primarily rich in frequencies of up to 15 Hz or thereabout As you finalize your work it might be worthwhile to run your model with a finer mesh i e more elements and to check that the results are of acceptable accu
22. s the incident component of seismic excitation A user specified input motion can be defined by selecting U Shake The input motion file to be defined should consist of two columns Time seconds and Acceleration g delimited by SPACE S Below is an example of a user defined input motion file 0 00 0 000 0 02 0 005 0 04 0 030 0 06 0 022 19 98 0 004 20 00 0 000 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 Scale Factor The amplitude of the input motion is multiplied by the Scale Factor The Scale Factor may be positive or negative Frequency The Frequency in Hz has to be specified if harmonic Sinusoidal Motion is chosen Number of Cycles The Number of Cycles has to be specified if Sinusoidal Motion is chosen Soil Properties Theory The liquefaction model Figure 1 employed in Cyclic1D Parra 1996 Yang 2000 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 Furthermore appropriate loading unloading flow rules were devised to reproduce the observed strong dilation tendency and resulting increase in cyclic shear stiffness and strength the Cyclic Mobility mechanism NOT
23. tional Viscous Damping In Cyclic1D additional viscous Rayleigh type damping is available of the form C AmM A K where M is the mass matrix C is the viscous damping matrix K is the initial stiffness matrix Am and A are two user specified constants The damping ratio curve f is calculated based on the following equation A f ree A f a where f is frequency 1 Specification of A and Ax By Defining Damping Ratios The user can define damping coefficients by specifying two frequencies f and f2 must be between 0 1 and 50 Hz and two damping ratios and suggested values are between 0 2 and 20 The Rayleigh damping parameters Am and A are obtained by solving the follow equations simultaneously As An f 47 fi b ae AT fy c 2 Direct Specification of Am and Ax The user can also directly define Rayleigh damping coefficients Am and Ax 16 Step by Step Time Integration Cyclic1D 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 Figure 4 Default values in Cyclic1D are y 0 55 and P y 4 4 Computations at any time step are executed to a convergence tolerance of 10 Euclidean Norm of acceleration vector normalized by the first iteration Error Norm predictor multi corrector approach Users can modify the specified
24. tton right after the user clicks it or vice versa File Location The report is in the form of a MS WORD file located in the working directory see Installation for details 21 Acknowledgments Cyclic1D is based on research underway since the early 1990s and a partial list of related publications is included in the References section The Cyclic1D graphical interface is written in Microsoft Visual C Professional Version 6 0 with Microsoft Foundation Class MFC Version 6 0 The Java Applet package used to display graphical results in Cyclic1D is obtained from the website http ptolemy eecs berkeley edu GIF images are generated with GNUPLOT for MS Windows 32 bit Version 3 7 available at http www gnuplot org 22 References Chan A H C 1988 A Unified Finite Element Solution to Static and Dynamic Problems in Geomechanics Ph D dissertation U College of Swansea U K Chopra A Dynamics of Structures 2000 Theory and Applications to Earthquake Engineering Prentice Hall Inc Inglewood Cliffs NJ Das B M 1983 Advanced Soil Mechanics Taylor and Francis Publisher Das B M 1995 Principles of Foundation Engineering Third Ed PWS Publishing Co Boston MA Elgamal A W 1991 Shear Hysteretic Elasto Plastic Earthquake Response of Soil Systems Journal of Earthquake Engineering and Structural Dynamics Vol 20 No 4 371 387 John Wiley Ltd Elgamal A Yang Z Parra E a
25. uding Dilation and Liquefaction 2000 Zhaohui Yang PhD Thesis Dept of Civil Engineering and Engineering Mechanics Columbia University NY New York 25 Dynamic Soil Properties Seismic Downhole Arrays and Applications in Practice 2001 A W Elgamal T Lai Z Yang and L He 4 International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics S Prakash Ed San Diego California USA March 26 31 Computational Modeling of Cyclic Mobility and Post Liquefaction Site Response 2002 A Elgamal Z Yang and E Parra Soil Dynamics and Earthquake Engineering 22 4 259 271 Influence of Permeability on Liquefaction Induced Shear Deformation 2002 Z Yang and A Elgamal J Engineering Mechanics ASCE 128 7 720 729 Numerical Analysis of Embankment Foundation Liquefaction Countermeasures 2002 A Elgamal E Parra Z Yang and K Adalier J Earthquake Engineering 6 4 447 471 Modeling of Cyclic Mobility in Saturated Cohesionless Soils 2003 A Elgamal Z Yang E Parra and A Ragheb Int J Plasticity 19 6 883 905 Application of unconstrained optimization and sensitivity analysis to calibration of a soil constitutive model 2003 Z Yang and A Elgamal Int J for Numerical and Analytical Methods in Geomechanics 27 15 1255 1316 Computational Model for Cyclic Mobility and Associated Shear Deformation 2003 Z Yang A Elgamal and E Parra J
26. user defined material click on the button associated with that material and fill in the pop up window User Defined Clay Rock Strata with No Pore Pressure Effects Non liquefiable clayey rock strata with shear response properties independent of confinement variation can be defined by specifying the following parameters Figure 2 1 Mass density in kg m suggested range of values between 1000 and 3000 kg m 2 Shear wave velocity in m s suggested range of values between 10 and 6000m s 3 Initial lateral vertical stress ratio also known as coefficient of lateral earth pressure at rest Ko suggested range of values between 0 1 and 0 9 In the program Ko is related to Poisson s ratio v by the following relation K v 1 v 4 Shear strength in kPa suggested range of values between 10 and 200000 kPa 5 Peak shear strain in suggested range of values between 0 001 and 20 6 Number of yield surfaces NYS Suggested range of values is 0 and 30 11 In particular NYS 0 dictates an elastic response Parameters 4 and 5 are ignored see Figure 2 NYS 1 indicates an elastic perfectly plastic response Parameter 5 is ignored see Figure 2 below Shear stress Shear strength X Number of yield 4 surfaces 5 Shear modulus Peak shear Shear Mass density x strain strain Shear wave velocity Shear Shear stress stress Shear strength Number of yield surfaces 0 Number of yield surfac
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