Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
O-1 APPENDIX O. MANUAL AND EXAMPLE OF TOP-DOWN CRACKING SOFTWARE One example is presented in this appendix to illustrate using the program named âTop- Down Cracking Softwareâ to compute the top-down initiation time, analyze the propagation of top-down cracking and predict calibration coefficients. The software provides the following results: 1. The plot of the length of longitudinal cracking against service time. 2. The value of calibration coefficients of Ï. 3. The value of calibration coefficient of . 4. The value of top-down cracking initiation time of . Example of Program Run of Top-Down Cracking Software Users should take the following step to perform the analysis of initiation time and propagation progress of top-down cracking: 1. Double click the application file âTopDownSoftware.exeâ to start the program. 2. Input the information including pavement structure, asphalt mixture material properties, traffic data and climate data. (See Figure 1) 3. Click âRun Analysisâ. The results will show up on the right side of the interface as shown in Figure 2. It can be observed from Figure 2 that the initiation time of top-down cracking is 3502 and the calibration coefficients of and are 4793.96 and 0.73, respectively. Figure O-1 Input Pavement Structure, Material Properties, Traffic and Climate Information
O-2 Figure O-2 Analysis Results for the Example. Interpretation of Inputs for Top-down Cracking Software Name, description and unit of each input and result are listed in Table 1 and Table 2, respectively.. Table O-1 List of Interpretation of Inputs Input name Description Units of input Surface Layer Thickness Representative thickness for asphalt mixture layer inch Asphalt Mixture Modulus Representative elastic modulus with the expression of | â| (where 1 ) MPa Base Layer Thickness Representative thickness for base layer inch Base Material Modulus Modulus of Base MPa Subgrade Modulus Modulus of Subgrade MPa Air Voids Air void percentage % Asphalt Content Asphalt content percentage % Gradation Parameter Model the curve of the cumulative percent passing against sieve size using power function of in which is gradation parameter
O-3 Model the curve of relaxation modulus of asphalt mixture again time using function of in which is a relaxation modulus parameter MPa m-value Model the curve of relaxation modulus of asphalt mixture again time using function of in which is a relaxation modulus parameter Load Spectrum (Annual Number of Axles) Select traffic characteristics at level 1 Alpha Single Tire Load Magnitude of accumulative single tire load Beta Single Tire Load Scale factor of accumulative single tire load Gamma Single Tire Load Shape factor of accumulative single tire load Alpha Dual Tire Load Magnitude of accumulative dual tire load Beta Dual Tire Load Scale factor of accumulative dual tire load Gamma Dual Tire Load Shape factor of accumulative dual tire load Annual Average Daily Truck Traffic (AADTT) Select traffic characteristics at level 2 AADTT Annual average daily truck traffic Wet Freeze (WF) Select wet freeze climate zone Wet Non Freeze (WNF) Select wet non freeze climate zone Dry Freeze (DF) Select dry freeze climate zone Dry Non Freeze (DNF) Select dry non freeze climate zone Annual Days Above 32oC Number of days where daily maximum air temperature is above 32.2oC, which is obtained from LTPP database Days Annual Days Below 0oC Number of days where daily maximum air temperature is below 0oC , which is obtained from LTPP database Days Weather Station Select an appropriate existing weather station to run analysis
O-4 Table O-2 List of Interpretation of Results Results Name Description Unit The value of rho Calibration coefficient of in top- down cracking propagation expression of Days The value of beta Calibration coefficient of in top- down cracking propagation expression of The value of Crack initiation time of in top- down cracking propagation expression of Days
