MICHPAVE User`s Manual - Michigan State University
Contents
1. MICHPAVE User s Manual Version 1 2 for DOS Asphalt o Base Roadbed ii 3 Ronald S Harichandran Gilbert Y Baladi MICHPAVE USER S MANUAL Version 1 2 for DOS by Ronald S Harichandran Associate Professor and Gilbert Y Baladi Professor Department of Civil and Environmental Engineering Michigan State University East Lansing MI 48824 1226 January 2000 1995 Michigan State University Board of Trustees ii We WO GU CH OMe aiina a EE e apctanaavccicadus E se atoms anettata es 1 2 Summary of Modeling and Analysis 224 s cncdseie ten taeda enue 1 2 1 Modeling of the Pavement ssnnssessseessseeesseesseessessseressetessresseesseesseeesseee 1 2 2 Granular and Cohesive Material Models n nnsneeessseeesseessseesseessessseresseee 1 23 Gravity and Lateral Stresses roserne r aay a 1 24 Pinte Element Analysis ocrni ae nn e a aeo Aee ie a 2 2 5 Computation of Stresses and Strains at Layer Interfaces eee 4 2 6 Estimated Equivalent Resilient Moduli eee ceeeeeesceeneenseeeseeeenees 4 2 7 Fatigue and Rut Depth Prediction eee eeeseeceseceeesececeseeeceeeeeeeteeeenaeees 4 eg System REMIT EIIC IOS 027 apts a E E E E E ae RER eee AE 4 4 Configuring the Computer sssessseessesseesseesseetssstessetssersseesseetessetsseesseesseessseessseesseest 5 4 1 Installation Procedures csisesisccssese tekeedseccztaetedeeeia dacs i a Ea a 5 42 ATS CONFIG SV SD ss e eea e2. Selection Figure 24 Menu for plots along horizontal cross sections 19 5 8 Printing the Results The output from the analysis stored in the file specified by the user may be printed from with in MICHPAVE or from the DOS environment When the printing option is chosen from within MICHPAVE EPSON compatible printers are automatically set to condensed mode so that the 132 character wide lines in the output file can be printed For printers whose code for setting condensed mode differs from that used for EPSON printers the print mode should be set externally by the user The DOS command MODE LPT1 132 can be used to set the line width of the printer on the parallel port LPT 1 to 132 characters It may be desirable to create a batch file to do this every time before running MICHPAVE and to reset the printer upon exit from MICHPAVE To print from the DOS environment set the printer width as outlined above and then simply use the PRINT command Any text editor can also be used to view the ASCII output files 6 Problem Reporting Although MICHPAVE has been tested quite extensively it is possible that errors causing the program to terminate abnormally may still be encountered if a haphazard sequence of options is used To report a problem note down the number and message displayed when the program termi nates abnormally and send it along with a diskette containing the input data file to Dr Ronald Harichandran or Dr Gilbert B
3. all elements have the same vertical dimension The number of elements in each layer in the vertical direction is dependent on the layer thickness but at least four elements are used in the top AC layer and at least two elements are used in all other lay ers A typical default finite element mesh is shown in Fig 3 Displacements stresses and strains are computed only within the region modeled by finite elements In order to increase accuracy and to reduce the memory and computation time required by the program the infinite extent of the last layer is modeled by using a flexible bottom boundary Harichandran and Yeh 1989 The half space below the bottom boundary is assumed to be homo geneous and linear elastic The modulus of the half space is taken as the average moduli of the fi nite elements immediately above the bottom boundary The non linear analysis consists of several iterations A linear analysis is performed in each iteration after which the resilient modulus of each finite element is revised if necessary If the Mohr Coulomb failure criterion is violated in any granular or cohesive soil element then the prin cipal stresses are modified to reflect the failure condition and the resilient moduli are determined from the modified stresses Raad and Figueroa 1980 The iteration is repeated until the resilient moduli of all the elements stabilize tort Asphalt it Sn ee ee Base iit 30 0
4. form shown in Fig 10 which is used to enter data for the fatigue life and rut depth calculations The data table below the form shows typical kinematic viscosities for different asphalt grades 1 The data that should be entered into the fatigue life and rut depth form are described below Average Annual Temperature The average annual air temperature expected at the pave ment location FATIGUE LIFE amp RUT DEPTH DATA 1 Average Annual Temperature 77 00 Fahrenheit 2 Percent Air Voids in Asphalt Mix 1 3 5 etc 3 00 3 Kinematic Viscosity 270 00 centistoke Asphalt Grade Typical Kinematic Viscosity centistokes AG 225 To AC 5 0 212 AC 10 270 Figure 10 Data entry form for fatigue life and rut depth 11 LAY ER TYPE 1 Asphalt or Linear 2 Granular 3 Cohesive Layer number from top Type 1 2 or 3 1 1 2 2 3 3 Figure 11 Data entry form for layer type 2 Percent Air Voids in Asphalt Mix The percent air voids in the asphalt mix as expected in the field 3 Kinematic Viscosity The kinematic viscosity of the asphalt binder 5 5 2 Option 2 Layer type The type of material used for each layer in the pavement section is identified by typing 1 2 or 3 for asphalt granular or cohesive soil layers respectively into the form shown in Fig 11 As phalt is treated as a linear elastic material in the analysis Lime asphalt or cement treated materials m
5. ROA 16 Typical display during computation sssesseseseseeseeseesseserestesstserestesstssresressessrssresseeee 17 Py picaldesten SUMMAT a ea OC ACG es Bie Ras E 17 Plot menu for selecting sections si 526684 5si0 4 sessed evans dace soasae teasedganasueedaavesedeedesessaatedasac 18 Menu for plots along vertical cross SCCtIONS ceeeeeeceeeeeesceceseceseeeeeeeeseecnaeenseesees 19 Menu for plots along horizontal Cross SCCtIONS sceeeceesceesteceeeeeeeeeeaeecsaeenseenees 19 List of Tables Keypad functions within data entry forms 00 0 ee eee eeeeceseeeseeeeseecaeceseenseeeeaeeeaeens 7 iv 1 Introduction MICHPAVE is a user friendly non linear finite element program for the analysis of flexible pavements The program computes displacements stresses and strains within the pavement due to a single circular wheel load Useful design information such as fatigue life and rut depth are also estimated through empirical equations Most of MICHPAVE is written in FORTRAN 77 Graphics and screen manipulations are performed using the FORTRAN callable GRAFMATIC graphics library marketed by Microcom patibles Inc 301 Prelude Drive Silver Spring MD 20901 2 Summary of Modeling and Analysis This section gives a summary of the modeling and analysis so that the user is aware of the capabilities and limitations of the MICHPAVE program Further details about the modeling and analysis and various sensitivity studies are given in the w
6. Roadbed E i i ie cee a ae en ee ee CEEE EE e EE 50 0 a E 10a Radial Distance in Radii Radius of loaded area a 5 35 in Figure 3 Typical finite element mesh 2 5 Computation of Stresses and Strains at Layer Interfaces For the interpolation functions used in the finite element approach stresses and strains are most accurate at the center of elements The following techniques are used to obtain improved es timates of some stresses and strains at layer interfaces e The vertical stress is obtained from the vertical stresses at the center of the two elements above and the two elements below the interface by using cubic interpolation e The radial tangential and shear stresses and vertical strain are obtained using extrapolation of the corresponding quantity at the center of the elements on one side of the interface If at least four elements are available then cubic extrapolation is used if three elements are available then quadratic extrapolation is used and if only two elements are available then linear extrapolation is used 2 6 Estimated Equivalent Resilient Moduli At the end of the analysis MICHPAVE outputs an equivalent resilient modulus for each pavement layer These equivalent moduli may be useful if further analyses is to be performed using other programs that assume linear elastic materials The equivalent moduli for each layer is com puted as the average of the moduli of the finite elements in that layer th
7. a E E 5 4 3 Required Amount of Free Memory ssssssssessesssesssssesseeessressresseesseeeeseee 5 4A Printing Graphics ee a A A N ES 5 4 5 Running MICHPAVE for the First Time ceeceeeseeeesseeeesseeeesteeeenaees 6 5 Using MICHPA VE cierna ae e E T Ra R E 6 5 1 Filiae Ss gin aan a cade deleted teased 6 5 2 Cursor Movement and Editing Keys eseesseessensseesseeesseesssesseesseesseeesseee 6 5 3 Title Sereen esssnonenusniinninini n en a e aias iae 7 54 o Main M ma enan cleaned ec cue Gite Seat a E ai 7 5 5 Data File Menus and Associated Data Entry FOrmSs ss ssseesessseeeseeeesee 9 5 0 PerforminS Analysis senn e a ge deh seiaes pated geese we mea 16 5 7 Plotting the Res ltS surmani N E ERTES 18 5 8 Prin ne th OR CSUs tupac etna dealin A a ENE 20 Ge Problem Reporting airn i Seg Secs e geste ied goes tan taceate tuner o ER S 20 6 References Table of Contents lil Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure 24 Table 1 List of Figures Resilient modulus model for granular soils 00 0 0 lee eeeeeeesee esse ceeeeeeeeeeseecnaeeneeeseeenaees 2 Resilient modulus model for cohesive SOIUS cee eeeeesceseeeeeceseceseeeeeeesaeessaeenseeneees 2 Typical finite element Meshterr e
8. are currently limited to 24 VERTICAL SECTION SPECIFICATIONS Optimal Locations for stress amp strain Region Radial Distance in Section Rad Dist in O a yTy Osta Oy 353 4 7 1 00 a 3a C14 9 4 12 0 14 7 2 4 7 3a 6a 18 7 24 1 29 4 Note 1 Radius of Loaded area a 5 35 inches 2 Optimal points for current finite element mesh Figure 17 Data entry form for specifying the location of vertical cross sections 15 MODIFY NUMBER OF ELEMENTS IN VERTICAL DIRECTION Layer Thickness Number of Elements 1 Asphalt 10 0 4 2 Base 20 0 5 3 Subgrade 20 0 3 Total vertical elements lt 24 when total hori elements 13 default value Figure 18 Data entry form for modifying the number of elements in the vertical direction After the required changes are made the data entry form shown in Fig 19 is displayed for modifying the number of elements in the horizontal direction and the current number of elements in the ranges 0 to a a to 3a 3a to 6a and 6a to 10a where a radius of loaded area are shown All elements within a given range have the same horizontal dimension 5 6 Performing Analysis The analysis portion of MICHPAVE consists of an initialization part several iterations for non linear material and a concluding part The number of iterations required for convergence of the non linear solution depends on the properties of the pavement section being an
9. be obtained if the locations of the horizontal sections correspond to the mid depths of elements Optimal locations within each layer corresponding to the mid depths of the elements in that layer are shown in the lower table HORIZONTAL SECTION SPECIFICATIONS Layer Name Thick in 1 Asphalt 10 0 Section No Depth inches 2 Base 20 0 3 Subgrade 20 0 1 00 2 10 00 Optimal Locations for stress amp strain 3 28 00 Layer Depths in 4 33 30 Ts 1 3 358 64 37 8 8 Figure 16 Data entry form for specifying the location of horizontal cross sections 14 on the right Nevertheless it is strongly recommended that horizontal sections be specified at each layer interface Note that the most critical stresses are compression at the top and tension at the bot tom of the AC surface and compression at the top of the roadbed soil The radial distances at which the vertical sections are located are specified in the data entry form shown in Fig 17 The first section must be located at the center of the loaded area r 0 Although the other vertical sections may be specified at any radial distance within the pavement modeled by finite elements 0 to 10 radii of the loaded area some stresses and strains are most accurately computed at the center of elements Thus best results will be obtained if the locations of the vertical sections correspond to the middle of an element In MICHPAVE the elements are grouped into three region
10. ILE MENU al Initial Data Load No of Layers Output Filename etc 2 Specify Layer Type 3 Specify Material Properties 4 Specify Cross Sections for Computation of Stresses amp Displacements 5 Plot Finite Element Mesh 6 Modify Finite Element Mesh 7 Return to Main Menu Selection Figure 8 New data file menu those used for modifying data files existing data is modified instead of specifying new data It is recommended that the options in the data file menu be followed in sequence When modifying an existing file it is mandatory to first use option 1 and specify new names for the required filenames or to indicate that the input and output files used earlier should be over written The other options may be performed in any sequence 5 5 1 Option 1 Initial fatigue life and rut depth data This option displays the data entry form shown in Fig 9 typical data is also shown in bold typeface INITIAL DATA 1 Filename to Save Data to I 96 dat 2 Filename to Output Results to I 96 out 3 Title Section of I 96 at Williamston 4 Number of Layers 3 max 6 5 Wheel Load 9000 0 1b 6 Tire Pressure 100 00 psi 7 Fatigue Life amp Rut Depth Computation Required Y N Y Figure 9 Data entry form for initial data 10 1 The data that should be entered into the fields are described below Filename to Save Data to All data that is entered in this and othe
11. aladi Department of Civil amp Environmental Engineering Michigan State University East Lansing MI 48824 1226 Alternatively report the problem by e mail to harichan egr msu edu or baladi egr msu edu References Baladi G Y 1989 Fatigue life and permanent deformation characteristics of asphalt concrete mixes Transporta tion Research Record 1227 75 86 Harichandran R S Baladi G Y and Yeh M S 1989 Development of a computer program for design of pave ment systems consisting of layers of bound and unbound materials Report No FHWA MI RD 89 02 Michi gan Department of Transportation Lansing Michigan Harichandran R S and Yeh M S 1989 Flexible boundary in finite element analysis of pavements Transporta tion Research Record 1207 50 60 Harichandran R S Yeh M S and Baladi G Y 1990 MICH PAVE A nonlinear finite element program for the analysis of flexible pavements Transportation Research Record 1286 123 131 Raad L and Figueroa J L 1980 Load response of transportation support system Journal of Transportation En gineering ASCE 106 111 128 Yeh M S 1989 Nonlinear finite element analysis of flexible pavements dissertation submitted in partial fulfill ment of the degree of Doctor of Philosophy Michigan State University East Lansing Michigan 20
12. alyzed and on the magnitude of the wheel load Weaker sections will in general require a larger number of itera tions for convergence The maximum number of iterations allowed is 25 Pavements requiring more iterations than this will probably be too weak to be practicable The stage of analysis and the time required for the previous stages are displayed on the screen during computation A typical dis MODIFY NUMBER OF ELEMENTS IN HORIZONTAL DIRECTION a contact radius Number of Elements 0 a 4 a 3a 3a 6a Note Radius of loaded area a 5 35 inches Figure 19 Data entry form for modifying the number of elements in the horizontal direction 16 CALCULATION IN PROGRESS PLEASE WAIT Initialization Completion time 0 min 24 sec Iteration 1 Completion time 0 min 50 sec Iteration 2 Completion time 1 min 2 sec Conclusion Completion time 0 min 24 sec Total computation time 2 min 40 sec Press any key to continue Figure 20 Typical display during computation play is shown in Fig 20 the times shown were obtained on a PC with 80286 and 80287 proces sors After the analysis is completed a design summary is displayed showing key design informa tion such as the maximum tensile strain at the bottom of the asphalt layer the average compressive strain in the asphalt layer the maximum compressive strain at the top of the roadbed soil the num ber of equiva
13. at lie within an assumed 2 1 load distribution zone Harichandran et al 1990 2 7 Fatigue and Rut Depth Prediction Results from the non linear mechanistic analysis together with other parameters are used as input to two performance models derived on the basis of field data Baladi 1989 to predict the fatigue life and rut depth These performance models are currently restricted to three layer pave ments with asphalt concrete AC surface base and roadbed soil and four layer pavements with AC surface base subbase and roadbed soil Fatigue life and rut depth estimates for other types of sections may be meaningless The models relate the fatigue life and rut depth to the number of equivalent 18 kip single axle loads surface deflection moduli and thicknesses of the layers per cent air voids in the asphalt tensile strain at the bottom of the asphalt layer average compressive strain in the asphalt layer kinematic viscosity of the asphalt binder and average annual air temper ature 3 System Requirements The MICHPAVE program was originally written for IBM compatible personal computers running under DOS Presently it is also available for Sun and Hewlett Packard workstations run ning under UNIX For DOS systems the following hardware and software are required PC DOS or MS DOS version 3 0 or higher e 640 KB of random access memory RAM e A hard disk e A color graphics adapter CGA EGA or VGA and compatible monitor Althou
14. ay be specified as type 3 To perform a linear analysis of the entire pavement section specify all layers to be of type 1 Specifying types 2 or 3 implies non linear analysis 5 5 3 Option 3 Material properties Three different sets of material properties are required for the three material types 1 2 and 3 Properties for layers with asphalt or linear elastic materials including the names of the layers thicknesses resilient moduli Poisson s ratios densities and coefficients of lateral earth pressure Ko are specified in the form shown in Fig 12 For compacted layers the locked in lateral stresses can be approximately accounted for by specifying a relatively large value for K e g larg er than 0 4 ASPHALT MATERIAL PROPERTIES Layer Name of Layer Thickness Modulus Poisson s Density Ko inches psi Ratio lb cu ft ik Asphalt 10 0 500000 0 35 150 0 40 Note Typical values for Ko are 4 undisturbed to 3 heavily compacted layer Figure 12 Data entry form for linear elastic type 1 material properties 12 Material Type Silty Sand Sand Crushed Gravel Slag Material Type K1 Sand Aggregate 4350 Partially Crushed Gravel 5967 Limerock 14030 Gravel Warning Values of K1 are dependent on the degree of saturation Figure 13 Data entry form for granular type 2 material properties GRANULAR MATERIAL PROPERTIES Layer Name of Layer Thick Ko K1 K2 u Co
15. creen Print Results on printer Exit Return to DOS OMNIA OA BWNE Selection Figure 6 Main menu e Option 8 Used after analysis to print results on the printer from within the MICHPAVE program The output requires a line width of 132 characters EPSON compatible printers are automatically set to condensed mode by the program e Option 9 Terminates the MICHPAVE program and returns to DOS 5 5 Data File Menus and Associated Data Entry Forms Data File Modify Current Data File and Modify Existing Data File menus are displayed when selecting options 2 3 or 4 respectively from the main menu All three menus are identical in structure and the first is shown in Fig 8 The only difference between these menus is that in MAIN MENU SUBMENUS 1 O0verview DATA FILE MENU Fatigue 2 Create a New Data File 1 Initial Data Data 3 Change Current Data File 2 Layer Type 1 Asphalt 4 Modify an Existing Data File 3 Material Properties 2 Granular 3 Cohesive 5 Perform Analysis 4 No of Cross Section for Comput of Stress amp Disp 6 Summary Results on Screen 5 Plot Finite Element Mesh Cross 7 Plot Results on Screen Section 6 Modify Finite Element Mesh Locations 8 Print Results on Printer 7 Return to Main Menu 9 Exit Return to DOS Press any key to return to main menu Figure 7 Overview flowchart of the MICHPAVE program DATA F
16. e computer system Which graphics adapter and monitor do you have MONO CGA EGA Is your computer strictly IBM compatible Y N Is your printer EPSON or EPSON compatible Y N The response to the above prompts are stored in a file named SYSTEM DAT When running MICHPAVE subsequently the system information is read from this file In case a mistake is made when specifying this information or if the graphics adapter in the computer or the printer is changed at a later time the file SYSTEM DAT should be deleted before running MICHPAVE so that it will prompt again for a description of the new hardware The graphics resolution for EGA systems will be substantially higher than for CGA systems For VGA systems specify EGA If the computer is not strictly IBM compatible then problems may be encountered with the data entry forms due to incompatibility with the graphics software if the computer had originally been specified as being fully IBM compatible By defining the computer to be not strictly IBM compatible MICHPAVE can still be used but some of the color used to enhance the data entry forms will be lost For EPSON compatible printers MICHPAVE automatically sets the print mode to condensed when printing the output after an analysis so that the 132 column wide output file is printed prop erly If the printer is not EPSON compatible then its print mode will need to be set externally be fore printing the output For an EPSON printe
17. erties 13 Dens pcf 120 0 CROSS SECTION SPECIFICATION MENU Number of Horizontal Sections 4 Number of Vertical Sections 2 Figure 15 Data entry form for specifying the number of cross sections along which results are computed ters K K2 K3 and Ky are given in the notes These parameters have currently not been established widely for different cohesive soils It should be noted that the thickness specified for the last layer roadbed soil controls the depth to which displacements stresses and strains are computed A thickness of about 6 to 12 is recommended For analysis the last layer is actually considered to be semi infinite 5 5 4 Option 4 Cross sections for computation of results Displacements stresses and strains are computed along horizontal and vertical cross sections specified by the user The number of horizontal and vertical sections are specified in the data entry form shown in Fig 15 At least one vertical section must be used The depths at which the horizontal sections are located are specified in the data entry form shown in Fig 16 To aid in these specifications the thickness of each layer in the pavement section is displayed in the upper table on the right Although the horizontal sections may be specified at any depth within the pavement in the finite element method some stresses and strains are most ac curately computed at the center of elements Thus best results will
18. gDn Move cursor to field below current one Backspace Delete character before cursor Del Delete character at cursor Ins Insert space at cursor gt Move cursor one space to the right Move cursor one space to the left Fl Check validity of entries in each field and save data If some of the data is invalid prompts will be issued for corrections Esc Discards any changes made on the current screen and return to previous screen 5 3 Title Screen When MICHPAVE is loaded the title screen shown in Fig 4 is displayed Pressing the F1 key displays the credits screen shown in Fig 5 while pressing any other key displays the main menu 5 4 Main Menu The main menu is shown in Fig 6 Any one of the nine options shown on the menu may be selected by typing a number from 1 to 9 These options are described below e Option 1 Displays the overview flowchart of the MICHPAVE program shown in Fig 7 e Option 2 Used to input data relating to a new pavement analysis problem e Option 3 Used to change data for the problem currently being worked on e Option 4 Used to read the data from a previously defined problem and modify it if nec essary The name of the file in which the previous data was saved will be requested e Option 5 Performs non linear finite element analysis after all the required data has been specified MICHPAVE creates two files named V PLT and R PLT after an analysis These files contain results used in subsequent plots e Option 6 D
19. ge esete es aS eiia Sek 3 ALVIS SOTO CN Se cassis n a R AE E ta aR a E R T N 8 Credits SCLC OTN ach 2S cee e n aE A A a eh eee R teens 8 Ma immen s soenan aee e ea a E a e a eaa ta 9 Overview flowchart of the MICHPAVE program sssesssessssseesseesserssereseeessseessress 9 Newdata fil Ment sin eoan i aea e A A A A 10 Data entry form for initial data seeeeeseeeeeeeeeseeeesseesreserrstessrsrresressrseresressessesrressesee 10 Data entry form for fatigue life and rut depth seeeseseeeseeesesesssesressrssresressesersrressesse 11 Data entry form for layer types enirn E a ean Buda A E 12 Data entry form for linear elastic type 1 material properties eee eeeeeeee 12 Data entry form for granular type 2 material properties eee eeeeeseeeneeeeeeeees 13 Data entry form for cohesive type 3 material properties eeeeeseseeeereererreresee 13 Data entry form for specifying the number of cross sections along which results are computed snnietec n jodecasesetawneaydancvsnstaa eG deaatasestaatoanedeacnaessanes 14 Data entry form for specifying the location of horizontal cross sections 14 Data entry form for specifying the location of vertical cross sections 8 15 Data entry form for modifying the number of elements in the vertical direction esto ses s e a a a a ice es e a isda r a 16 Data entry form for modifying the number of elements in the horizontal difect n csngs srssudennrannn na Ne a A
20. gh not strictly required for the use of the program the following hardware is strongly recommended e A math co processor 8087 80287 or 80387 Running time will be greatly increased if a math co processor is not installed e A printer for obtaining hardcopies of plots and output 4 Configuring the Computer 4 1 Installation Procedure The MICHPAVE program is initially supplied a diskettes To install the program on a hard disk first make a subdirectory to hold the program e g MD MPAVE change to this directory e g CD MPAVE insert the diskette in drive A and type COPY A 4 2 The CONFIG SYS File In the root directory there is a file named CONFIG SYS which configures the PC system and loads any requested device drivers when the computer is turned on The following statement will need to be added to the CONFIG SYS file if it does not already exist FILES 20 The MICHPAVE program uses a FORTRAN callable graphics package called GRAFMATIC Unfortunately this package is not compatible with the ANSI SYS device driver used by some other programs for screen manipulations Thus if the CONFIG SYS file has the statement DEVICE ANSI SYS then this statement will need to be removed and the computer re booted by simultaneously press ing the CTRL ALT and DEL keys before running MICHPAVE If available use of an ANSI SYS compatible device driver that can be unloaded from memory on demand is convenient since
21. hesion o Density in psi psf degree pcf 2 Base 20 0 40 9000 0 35 40 0 30 0 120 0 Resilient Modulus Kl 61 62 63 K2 Properties for granular layers including the names of the layers thicknesses coefficients of lateral earth pressure Ko K and K parameters Poisson s ratios u cohesions friction angles and densities are specified in the form shown in Fig 13 Typical values of the parameters K and K for a variety of granular soils are displayed in the table below the form Properties for cohesive layers including the names of the layers thicknesses coefficients of lateral earth pressure Kg K K gt K3 and K4 parameters Poisson s ratios u cohesions friction angles p and densities are specified in the form shown in Fig 14 Typical values of the parame COHESIVE MATERIAL PROPERTIES Layer Name of Thick Ko Kl K2 K3 K4 u Coh o Layer in psi psi psf deg 3 Roadbed 20 0 40 6 0 3020 0 1110 0 178 45 800 0 0 Note 1 Typical values for Kl K2 K3 K4 Ki 6 psi K2 3020 psi K3 1110 K4 178 2 Resilient Modulus K2 K3 Kl 01 63 K1 gt 61 63 Resilient Modulus K2 K4 o01 03 kl K1 lt ol 03 3 u Poisson s Ratio 0 lt U lt 5 4 Layer 3 actually semi infinite but thickness controls depth to which displacements stresses are computed Figure 14 Data entry form for cohesive type 3 material prop
22. isplays a summary screen containing the results commonly used in design This option can only be used following an analysis e Option 7 Plots displacements stresses and strains on the screen along requested vertical and horizontal sections This option is normally selected after an analysis If chosen before an analysis the results from the previous analysis are plotted if the files V PLT and R PLT have not been erased Version 1 2 MICHPAV GI Nonlinear Finite Element Program for Analysis of Flexible Pavements Developed for Michigan Department of Transportation by Dept of Civil amp Environmental Engineering Michigan State University East Lansing MI 48824 1226 For further information call 517 355 5107 F1 to list credits Press any key to start Figure 4 Title screen MICHPAVE Version 1 2 April 1994 Conceptual Development by Ronald S Harichandran Gilbert Y Baladi and Ming Shan Yeh Ported to UNIX by Ronald S Harichandran and Baoyan Wu Development of Version 1 0 for DOS Funded by Michigan Department of Transportation Acknowledgement Various State Highway Agencies provided the data used to develop the rut and fatigue models Press any key to start Figure 5 Credits screen MAIN MENU E Overview Create a New Data File Change Current Data File Modify an Existing Data File Perform Analysis Type summary results on screen Plot Results on s
23. it elim inates the need to re boot the computer 4 3 Required Amount of Free Memory The MICHPAVE program requires about 515 KB of free memory to run DOS and memory resident programs such as SIDEKICK reduce the amount of free memory for use by other pro grams The amount of free memory available can be checked by using the DOS command CHKDSK If there is insufficient free memory then memory resident programs will need to be re moved before running MICHPAVE If there is insufficient memory to load the program the following message will be displayed Program too big to fit in memory Sometimes the program may load into memory without any problem but the following error mes sage may be displayed during computations Run time error F6700 heap space limit exceeded This also indicates that there is insufficient free memory 4 4 Printing Graphics Graphic screens produced by MICHPAVE can be dumped onto an attached printer if the DOS command GRAPHICS COM is issued after the computer is turned on and before MICH PAVE is used It may be convenient to include the command in the AUTOEXEC BAT file so that it is issued every time the computer is turned on To download graphics that are on the screen to the printer simply press the SHIFT and PrScr keys simultaneously 4 5 Running MICHPAVE for the First Time To run MICHPAVE simply type MICHPAVE When running for the first time the program will request the following information about th
24. l and hori zontal sections previously specified by the user by selecting from the menu shown in Fig 22 The menu in Fig 23 is used to select the quantities that may be plotted along vertical sections The vertical compressive and radial tensile stresses and the radial tensile strains are the quantities that are commonly plotted These are grouped together and other quantities that may be plotted are grouped below them The menu in Fig 24 is used to select the quantities that may be plotted along horizontal sec tions The vertical compressive stresses and the vertical deflections are the quantities that are com monly plotted These are grouped together and other quantities that may be plotted are grouped below them 18 PLOT RESULTS AT VERTICAL SECTIONS MENU 1 Compressive Vertical stresses 2 Tensile Radial stresses 3 Tensile Radial strains 4 Compressive Vertical strains 5 Vertical deflections 6 Radial displacements 7 Shear stresses 8 Tangential stresses 9 Return to plot results menu Selection Figure 23 Menu for plots along vertical cross sections PLOT RESULTS AT HORIZONTAL SECTIONS MENU 1 Compressive Vertical stresses 2 Vertical deflections 3 Tensile Radial stresses 4 Tensile Radial strains 5 Compressive Vertical strains 6 Radial displacements 7 Shear stresses 8 Tangential stresses 9 Return to plot results menu
25. lent standard axle loads required to cause fatigue failure and the rut depth at the fa tigue life A typical summary is shown in Fig 21 The caution statement at the bottom of the table is a warning that if the estimated fatigue life is greater than 20 million load repetitions then failure would most probably occur due to thermal cracking rather than fatigue The implication here is that 20 million ESAL will span a period of greater than 15 to 20 years Hence asphalt hardening and block cracking should be considered DESIGN SUMMARY 1 Max Tensile strain in the asphalt layer 1 116e 04 2 Average compressive strain in the asphalt layer 8 947e 05 3 Max compressive strain at top of subgrade 1 112e 04 4 Fatigue life of asphalt pavement 1 204e 08 ESAL 5 Total expected rut depth of the pavement 1 885e 01 in 6 Expected rut depth in the asphalt course 6 966e 02 in 7 Expected rut depth in the base and or subbase course 9 097e 02 in 8 Expected rut depth in the roadbed soil 2 791e 02 in Caution Thermal cracking of the pavement needs to be evaluated Figure 21 Typical design summary 17 PLOT RESULTS MENU 1 Plot results at vertical sections 2 Plot results at horizontal sections 3 Return to main menu Selection Figure 22 Plot menu for selecting sections Following the summary results the following questions will be asked Output fatigue life and summar
26. lient modulus model for granular soils O0 Ko0 where K coefficient of earth pressure at rest For granular soils Kg 1 sin and for cohesive soils K 1 0 95 sin where angle of internal friction To approximately account for locked in stresses caused by compaction the user can input a value for Kg higher than the coefficient of earth pressure at rest 2 4 Finite Element Analysis Rectangular four noded axisymmetric finite elements with linear interpolation functions are used in all upper layers and through the depth specified by the user for the last layer the roadbed A lateral boundary is placed at a radial distance of 10a from the center of the loaded area where a radius of the loaded area A default mesh is initially generated but this may be modified by the user The default mesh has the following characteristics Mr K 01 03 Figure 2 Resilient modulus model for cohesive soils e In the radial direction the total width of 10 radii is divided into four regions Within any region all elements have the same horizontal dimension The first region between 0 and 1 radius is equally divided into four elements the second region between 1 radius and 3 ra dii is equally divided into four elements the third region between 3 radii and 6 radii is equally divided into three elements and the fourth region between 6 radii and 10 radii is equally divided into two elements Within any layer
27. orks by Yeh 1989 and Harichandran et al 1989 1990 2 1 Modeling of the Pavement Each layer in a pavement cross section is assumed to extend infinitely in the horizontal direc tions and the last layer is assumed to be infinitely deep All the pavement layers are assumed to be fully bonded so that no slip occurs due to applied load Displacements stresses and strains due to a single circular wheel load are computed Due to the assumptions used the problem is reduced to an axisymmetric one 2 2 Granular and Cohesive Material Models The so called K O model is used to characterize the resilient moduli of granular type 2 ma terials This model is of the form Mp K0 in which 0 0 63 bulk stress and Mp resilient modulus and K and are material properties For this model log Mp varies linearly with log O as shown in Fig 1 The resilient modulus for cohesive soils is specified in terms of the deviatoric stress through the bilinear model Kere when o 03 S lt K R This model is illustrated in Fig 2 2 3 Gravity and Lateral Stresses The MICHPA VE program includes the effect of gravity and lateral stresses arising from the weight of the materials At any location within the pavements the vertical gravity stress is computed as the accumulation of the layer thicknesses multiplied by the appropriate unit weights The lateral stress is taken as log Mp Ky log K gt log 0 Figure 1 Resi
28. r forms is stored in this file The data may be recovered at a later time and modified if necessary Filename to Output Results to The output from the analysis will be directed to this file The output is in standard ASCII form and may be viewed or edited using any text editor It should be noted however that a line width of 132 characters is used for the output Title This is a description of the current job for identification purposes Number of Layers The number of layers in the pavement section A maximum of six lay ers are permitted Note that the roadbed soil subgrade is counted as one layer Wheel Load Equal to half the axle load in pounds Tire Pressure The pressure in the truck tire in psi Fatigue Life amp Rut Depth Computation Required Y N The user should respond with a Y if fatigue life and rut depth in the section are to be estimated Empirical expressions are used to relate the fatigue life and rut depth to results from the mechanistic analysis These relations are currently valid only for three layer pavements with AC base and roadbed soil layers and for four layer pavements with AC base subbase and roadbed soil layers Bal adi 1989 Fatigue life and rut depth estimates for other pavement sections may not be meaningful The rut depth is estimated for the number of load repetitions causing fatigue failure of the pavement Answering in the affirmative to question 7 in the Initial Data form displays the data entry
29. r with a wide carriage capable of printing 132 characters per line in normal mode specify the printer to be non EPSON compatible 5 Using MICHPAVE MICHPAVE is designed to be user friendly Menus are used to perform the required steps in pavement analysis and data entry forms facilitate data input In addition extensive checking of in put data is performed and appropriate error messages are displayed upon completion of each data entry form 5 1 Filenames The names of files in which the data and results are saved may include a pathname if neces sary e g A I 96 DAT to save the file I 96 DAT on the diskette in drive A JOB1 I 96 DAT to save the file in subdirectory JOB1 etc If no path is specified the file will be saved in the default subdirectory 5 2 Cursor Movement and Editing Keys The data entry forms have several fields into which data is typed The field in which the cur sor resides is highlighted on IBM compatible systems The functions of the cursor movement and editing keys within a data entry form are described in Table 1 TABLE 1 KEYPAD FUNCTIONS WITHIN DATA ENTRY FORMS KEY Function Return Enter Move cursor to next field Tab Move cursor to next field on the right Shift Tab Move cursor to previous field on the left Home Move cursor to first field in the form End Move cursor to last field in the form T or PgUp Move cursor to field above current one J or P
30. s in the radial direction from 0 to a a to 3a 3a to 6a and 6a to 10a where a radius of loaded area Optimal radial locations corresponding to the middle of the elements are shown in the table on the right Due to edge effects of the right boundary it is recommended that vertical section not be specified in the last region from 6a to 10a The radius of the loaded area is shown in the note below the tables 5 5 5 Option 5 Plot finite element mesh This option plots the current finite element mesh on the screen The loaded region and the radius of the loaded area a are also shown Fig 3 shows a typical finite element mesh for the mesh parameters given in bold typeface in Figs 18 and 19 5 5 6 Option 6 Modify finite element mesh This option is used to modify the current finite element mesh MICHPAVE automatically generates a default mesh that should be sufficient for most purposes However for greater accura cy or for unusual situations the user may wish to modify the default mesh Memory limitations may however preclude the use of a very fine large mesh First the data entry form shown in Fig 18 is displayed for modifying the number of elements in the vertical direction and the current num ber of elements within each layer are shown All elements within a given layer have the same ver tical dimension For the default number of elements in the horizontal direction 13 the maximum number of elements in the vertical direction
31. y results to printer Y N Recompute fatigue life and rut depth with different data Y N These questions allow the user to output the summary results to the printer and to recompute new fatigue life and rut depth estimates for different values of annual temperature and kinematic vis cosity of the asphalt binder Answering in the affirmative to the second question displays the Fa tigue Life and Rut Depth data entry form see Fig 10 on which these input data may be changed Note that the re estimation of the fatigue life and rut depth for changes in this data is done using empirical equations and does not require a re analysis Also note that this is the only stage at which fatigue life and rut depth may be estimated for the pavement for new input data without perform ing a re analysis If the fatigue life and rut depth are not recomputed at this stage but are desired at a later time for the same pavement section then the analysis will need to be performed again All calculations of the fatigue life and rut depth will be saved in the output file 5 7 Plotting the Results After an analysis the results may be plotted When this option is chosen before an analysis the results from the previous analysis will be plotted provided the files V PLT and R PLT which contain the data for plots have not been deleted Every analysis overwrites these plot files so that only one set is maintained at any given time Results may be plotted along the vertica
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