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Civil and Environmental Engineering Commons

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1984

CBR

Articles 1 - 3 of 3

Full-Text Articles in Civil and Environmental Engineering

Variable Serviceability Concept For Pavement Design Confirmed By Aasho Road Test Fatigue Data, Herbert F. Southgate, Robert C. Deen Apr 1984

Variable Serviceability Concept For Pavement Design Confirmed By Aasho Road Test Fatigue Data, Herbert F. Southgate, Robert C. Deen

Kentucky Transportation Center Research Report

Fatigue data from the AASHO Road Test were plotted for each level of serviceability. The Kentucky thickness design system uses the concept of a variable level of serviceability as a function of EALs. The Kentucky thickness design curve for the equivalent CBR was converted to an equivalent structural number and superimposed on each of the specific serviceability figures. The AASHTO Equation C–14 of the 1972 AASHTO Interim Guide was evaluated for each level of serviceability and superimposed on its respective figure. Equation C–14 fits reasonably well for serviceability levels of 2.0 and 2.5 but does not fit the remining serviceability …


Variations Of Fatigue Due To Unevenly Loaded Axles Within Tridem Groups, Herbert F. Southgate, Robert C. Deen Apr 1984

Variations Of Fatigue Due To Unevenly Loaded Axles Within Tridem Groups, Herbert F. Southgate, Robert C. Deen

Kentucky Transportation Center Research Report

The effect of unevenly distributed loads on the axles within a tridem has been shown to be very significant. Equations are presented that enable the equivalent load effect for equal load distribution to be adjusted for uneven loading. Considering the relative increase and the relatively small volume of trucks currently using tridems, the equation for all tridems without regard to locations on the vehicle is recommended at this time. Consideration should be given to using equations for individual load patterns as the volume of trucks using tridems increases and more weight data become available.


Thickness Design Curves For Portland Cement Concrete Pavements, Herbert F. Southgate, Robert C. Deen Feb 1984

Thickness Design Curves For Portland Cement Concrete Pavements, Herbert F. Southgate, Robert C. Deen

Kentucky Transportation Center Research Report

Past experience indicates that thickness designs using portland cement concrete best agree with criterion used in the Portland Cement Association's design method for 18-kip EAL of 2 to 3 million or less. For EALs greater than 2 to 3 million, past experience best agrees with criterion developed from the AASHO Road Test. Research herein indicates the two criterion become asymptotic to each other at approximately 2.5 million EAL. For a variation in thickness and elastic moduli in portland cement concrete, dense-graded aggregate, and sub grade elastic modulus, research indicates that a general conic equation (included herein) very closely duplicates the …