![]() ![]() Thus, this pamphlet and its companions are critically important to anyone who designs flexible pavements. Furthermore, although the procedures are specifically developed for use with the 1993 AASHTO Guide, their use will give agencies a "leg up" on implementation of the design procedures being developed for inclusion in the 2002 AASHTO Guide for Design of New and Rehabilitated Pavement Structures. Their use will provide: (1) improved designs, (2) more realistic estimates of pavement performance, and (3) more consistent use of the AASHTO design parameters. The procedures presented were developed through analysis of the Long-Term Pavement Performance (LTPP) data, documented in the report Analyses Relating to Pavement Material Characterization and Their Effects on Pavement Performance, FHWA-RD-97-085.Īpplication of the procedures and guidelines developed through this analysis will facilitate and improve application of the AASHTO Guide flexible pavement design procedures. of LTPP General Pavement Study Sites (FHWA-RD-97-086). Two companion pamphlets-Design Pamphlet for the Determination of Design Subgrade Moduli in Support of the 1993 AASHTO Guide for the Design of Pavement Structures (FHWA-RD-97-083) and Design Pamphlet for the Back-calculation of Pavement Layer Moduli in Support of the 1993 AASHTO Guide for the Design of Pavement Structures (FHWA-RD-97- 076)-provide additional, related guidance on interpretation of pavement deflection data and characterization of the subgrade soil. A key design challenge faced by engineers using the 1993 AASHTO Guide for Design of. This design pamphlet addresses this problem by presenting procedures for selecting appropriate design values to characterize the pavement materials. ![]() Until now, the information available to help engineers choose appropriate values has been incomplete. This includes detailed information and typical values for all the required inputs and an explanation of the design standards and principles used in the spreadsheet.PDF files can be viewed with the Acrobat® Reader® FOREWORDĪ key challenge faced by engineers using the 1993 AASHTO Guide for Design of Pavement Structures (AASHTO Guide) is the selection of appropriate design values for the subgrade soil and for the pavement materials. To do this hypothetical joint spacings can be input to adjust the equations to give a suitable result for pavement thickness.įor JRCPs the actual joint spacing should be used up to a maximum of 9m. The joint spacing was the focus of the alterations made to the original AASHTO 1993 rigid pavement design equations and for this reason the AASHTO 1998 rigid pavement design Supplement is best suited to the design of JPCPs. ![]() These climate inputs can also be input directly by the designer for use in other parts of the US or for any locations outside of the US. The CivilWeb AASHTO Rigid Pavement Design Spreadsheet includes typical climate info for more than 130 major US cities and regions. This is calculated using the below equation where f is the friction coefficient as shown for in the below table for different road foundation materials. This is calculated in the same way as for the Westergaard Method, the equation is reproduced below where is Poissons Ratio for concrete, typically taken as 0.15 or 0.2. This can be calculated using the below equation where E c is the concrete slabs modulus of elasticity, E b is the road foundation modulus of elasticity, H b is the road foundation thickness, k is the effective elastic modulus of the subgrade. This must be calculated for both the AASHTO Road Test constants and using the 1998 rigid pavement design supplement constants. These publications will be available in late 1997. This equation assumes a 50 reliability where W is the number of standard axles for the traffic lane considered. Elastic Moduli in Support of the 1993 AASHTO Guide for Design of Pavement Structures(FHWA-RD-97-077). Pati parmeshwar 1990įor this reason it is the AASHTO 1998 supplement which powers the CivilWeb AASHTO Rigid Pavement Design Spreadsheet. The updated 1998 procedure works in a similar manner to the 1993 procedure but includes for the effects of joint spacing.Īs such this was a great improvement on the original 1993 method and it is the 1998 Supplement method which is most applicable to designing concrete roads. This time the method was not based upon data obtained from the AASHTO Road Test but on the LTPP database NCHRP project 1-30. Modifications incorporated into 1993 Guide included major revisions of the overlay design procedures, such as. However, the AASHTO 1993 rigid pavement design model is still commonly used in many parts of the world and is very useful as a simple tool for evaluating required concrete road thicknesses at preliminary stage. AASHTO Guide for the Design of Pavements (1993). This has since been superseded by a much more complex mechanistic design procedure known as the Mechanistic-Empirical Design Guide (MEDG). ![]()
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