LOAD EQUIVALENCY IN FLEXIBLE PAVEMENTS

AN HISTORICAL REVIEW AND STUDY IS CONDUCTED OF THE LOAD EQUIVALENCY FACTOR FOR ANALYSIS OF PAVEMENT LOADING. THE FOLLOWING THREE MAJOR ASSUMPTIONS ON WHICH THE LOAD EQUIVALENCY CONCEPT IS BASED ARE: (1) THE EFFECT OF ANY AXLE LOAD CAN BE EXPRESSED IN TERMS OF AN EQUIVALENT NUMBER OF APPLICATIONS OF ANY SELECTED AXLE LOAD, (2) THE COMBINED EFFECT ON ALL AXLE LOADS CAN BE EXPRESSED IN TERMS OF THE COMBINED NUMBER OF EQUIVALENT APPLICATIONS OF THE DESIGNATED AXLE LOAD, AND (3) THE EFFECT OF MIXED TRAFFIC CAN BE INTRODUCED INTO A SINGLE-LOAD EQUATION FOR THE DESIGNATED AXLE LOAD BY MEANS OF THE COMBINED NUMBER OF EQUIVALENT APPLICATIONS OF THE DESIGNATED AXLE LOAD. THE METHODLOLOGY IS PRESENTED FOR COMPUTING THE LOAD EQUIVALENCY FACTORS. CONCLUSIONS OF THE STUDY INDICATE THAT: (1) THE CONCEPT OF LOAD EQUIVALENCY IS A VALID WAY FOR DESCRIBING THE RELATIVE DESTRUCTIVE EFFECTS IN FATIGUE OF AXLE LOADS OF VARYING MAGNITUDE AND CONFIGURATION, (2) CURRENT KNOWLEDGE OF THE FATIGUE BEHAVIOR OF BITUMINOUS MIXTURES COUPLED WITH THE AVAILABILITY OF APPROPRIATE ANALYTICAL TECHNIQUES ENABLE THE THEORETICAL DERIVATION OF LOAD EQUIVALENCY FACOTRS, (3) FOR COMPARABLE LOAD MAGNITUDES, SINGLE TIRES ARE APPROXIMATELY THREE TIMES AS DESTRUCTIVE WITH RESPECT TO FATIGUE AS DUAL TIRES, (4) A SINGLE AXLE LOAD WHICH IS EQUIVALENT IN DESTRUCTIVE EFFECT TO A TANDEM AXLE LOAD HAS A MAGNITUDE WHICH IS 57% OF THE TANDEM AXLE LOAD, (5) THEORETICAL LOAD EQUIVALENCY FACTORS ARE NOT AFFECTED SIGNIFICANTLY BY VARIATIONS IN SUBGRADE MODULUS FOR NORMAL PAVEMENT SECTIONS, (6) THE STRUCTURAL NUMBER OF A PAVEMENT SECTION IS NOT SUFFICIENT IN ITSELF TO ACCURATELY DESCRIBE THE LOAD EQUIVALENCY FACTORS, AND (7) THE THEORETICAL FACTORS DERIVED SUPPORT CONTINUED USE OF THE AASHO EQUIVALENCY FACTORS IN DESIGN SITUATIONS.

• Supplemental Notes:
  • Vol 38, pp 465-494, 8 FIG, 9 TAB, 41 REF
• Authors:
  • Deacon, J A
  • Fin, F N
  • Hudson, W R
  • HINDERMANN, W L
  • Warden, W B
  • Monismith, C L
• Discussers:
  • Obrcian, V
• Conference:
  • Association of Asphalt Paving Technologists Proc
• Publication Date: 1969-2

Subject/Index Terms

• TRT Terms: Axle load force; Bituminous mixtures; Coefficient of subgrade reaction; Design load; Flexible pavements; Loads; Reviews; Tandem axle loads
• Uncontrolled Terms: Loading
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00211508
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 27 1970 12:00AM