WHAT IS MICHPAVE? MICHPAVE is a user-friendly, menu driven, nonlinear finite element computer program for the analysis of flexible pavements. The program computes displacements, stresses and strains within the pavement due to a single circular wheel load, and is able to account for the stress-dependent behavior of granular and cohesive soil layers in the pavement cross section. Computed responses may be displayed graphically. Useful design information such as fatigue life are also estimated through empirical equations. The program is available for personal computers running the DOS operating system, and may also be run in a DOS window on computers running Windows 3.x/95/NT. The development of MICHPAVE Version 1.0 for DOS was supported by the Michigan Department of Transportation. STRENGTHS OF MICHPAVE MICHBACK has many user-friendly features and advantages over other nonlinear finite element programs. It: - is menu-driven - has on-screen forms to facilitate data entry, with error trapping - has built-in nonlinear material models specific to granular and cohesive soils - uses a flexible bottom boundary to enhance accuracy while at the same time speeding up computations - accounts for gravity and lateral stresses and enables "locked-in" stresses caused by compaction to be modeled approximately - uses interpolation to more accurately estimate stresses and strains at layer interfaces - predicts the fatigue life and rut depth using empirical models calibrated to field data (Baladi 1989) - can graphically display computed responses COMPUTER REQUIREMENTS MICHPAVE Version 1.2 for DOS requires the following hardware and software: - MS-DOS Version 3.0 or higher - 640 KB of memory (RAM) with at least 515 KB of free memory - A hard disk - A color graphics adapter (CGA, EGA or VGA) and compatible monitor Although not strictly required for the use of the program, the following hardware is strongly recommended: - 386 or later PC - math co-processor - printer PACKAGE COMPONENTS The following files are included in this distribution of MICHPAVE: 1. readme.txt - An ASCII file containing an overview and installation instructions. 2. copyright.txt - An ASCII file containing the end user agreement. 3. michpave.exe - The executable program file. 4. mpmanual.pdf - Adobe PDF file containing the user's manual. This may be viewed/printed using the free Adobe Acrobat Reader software. 5. mpmanual.ps - PostScript file containing the user's manual. This can only be printed on a PostScript printer. 6. sample.dat - Sample input data file. 7. sample.out - Sample output file generated by using "sample.dat". The supplied files can be used to generate screen images of most of the figures in the User's Manual without having to perform an analysis. CONFIGURING THE COMPUTER Installation Procedure To install the program on a hard disk, first make a subdirectory to hold the program (e.g., MD \MICHPAVE), change to this directory (e.g. CD \MICHPAVE), and copy all files in the distribution to this directory. 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 pressing 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 it eliminates the need to re-boot the computer. 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 programs. The amount of free memory available can be checked by using the DOS commanCHKDSK. If there is insufficient free memory, then memory resident programs will need to be removed 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 message may be displayed during computations: Run-time error F6700: -heap space limit exceeded. This also indicates that there is insufficient free memory. 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 MICHPAVE 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. 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 the 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 properly. If the printer is not EPSON compatible, then its print mode will need to be set externally before printing the output. For an EPSON printer with a wide carriage capable of printing 132 characters per line in normal mode, specify the printer to be non-EPSON compatible. FUTURE OF MICHPAVE MICHPAVE is being combined with the MICHBACK backcalculation program to provided a self-contained mechanistic pavement design system (MPDS) for the Windows 95/NT operating system. Overlay design, AASHTO thickness design and elastic layer analysis will be included within MPDS. A fine mesh and distant lateral boundary can be used in MPDS to obtain accurate responses. MPDS is scheduled to be released in 1999 or 2000. REFERENCES Baladi, G.Y. (1989). "Fatigue life and permanent deformation characteristics of asphalt concrete mixes," Transportation Research Record, 1227, 75-86. Harichandran, R.S. and Yeh, M-S. (1989). "Flexible boundary in finite element analysis of pavements," Transportation 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.