A THEORETICAL AND EXPERIMENTAL STUDY OF DYNAMIC HIGHWAY LOADING

A GENERALIZED MATHEMATICAL MODEL WHICH CHARACTERIZES THE DYNAMIC BEHAVIOR OF FIVE DIFFERENT CLASSES OF HIGHWAY VEHICLES IS DESCRIBED IN THIS REPORT. THE MODEL CONSISTS OF A SERIES OF INTERCONNECTED MASSES, SPRINGS, AND DASHPOTS AND IS USED TO PREDICT THE MAGNITUDE, DURATION, AND LOCATION OF DYNAMIC WHEEL LOADS APPLIED NORMALLY TO THE ROADWAY SURFACE BY THE WHEELS OF SINGLE UNIT AND ARTICULATED VEHICLES OPERATING UNDER VARIOUS CONDITIONS. THE MODEL MAY BE FORCED BY A SIMULATED ROAD PROFILE MADE UP OF AN ARRAY OF BUMPS WITH DIFFERENT SIZES AND ARRANGEMENTS IN EACH WHEEL PATH, OR MORE REALISTICALLY, IT MAY BE FORCED BY A NATURAL PROFILE RECORDED IN THE FIELD BY A ROAD PROFILOMETER AND CONVERTED TO A SUITABLE DIGITAL FORMAT. BESIDES THE ROADWAY PROFILE, REQUIRED INPUT FOR THE MODEL CONSISTS OF STATIC WHEEL LOADS, NUMERICAL QUANTITIES ASSIGNED TO THE PHYSICAL CHARACTERISTICS OF THE VEHICLE SUSPENSION SYSTEM, AND AXLE SPACING. A COMPUTER PROGRAM WHICH SOLVES THE SETS OF DIFFERENTIAL EQUATIONS USED TO DESCRIBE THE MOTION OF EACH VEHICLE AND CALCULATES THE FORCES BETWEEN THE TIRE AND THE ROAD SURFACE HAS BEEN WRITTEN IN FORTRAN LANGUAGE FOR THE CDC 6600 COMPUTER AND IS DOCUMENTED WITH EXAMPLE PROBLEMS. IN A STATISTICALLY DESIGNED EXPERIMENTAL PROGRAM, DYNAMIC WHEEL FORCES WERE MEASURED AT NINE SELECTED POSITIONS ALONG A 64-FOOT SECTION OF ROADWAY BY SPECIAL STRAIN-GAGE TYPE WHEEL LOAD TRANSDUCERS. FIVE REPRESENTATIVE TEST VEHICLES MADE THREE PASSES AT EACH OF THREE SPEEDS OVER FOUR PATTERNS OF ARTIFICIAL ROAD SURFACE ROUGHNESS AND RESULTED IN 3,672 OBSERVATIONS OF WHEEL LOAD IN THE LEFT WHEEL PATH AND 1,836 MEASUREMENTS IN THE RIGHT WHEEL PATH. A DESCRIPTION OF THE WHEEL LOAD TRANSDUCER AND THE ELECTRONIC DATA COLLECTION SYSTEM USED IN THIS PROGRAM IS INCLUDED IN THIS REPORT. THE RESULTS OF THE EXPERIMENTAL PROGRAM WERE USED TO CALIBRATE THE MODEL AND TO PROVIDE A VALIDATION OF THE ACCURACY OF THE MODEL. THE EFFECTS OF PAVEMENT ROUGHNESS, SPEED, VEHICLE TYPE, AND THEIR INTERACTIONS ON THE MAGNITUDE OF DYNAMIC WHEEL LOADS ARE DISCUSSED. EXPERIMENTAL DEVICES FOR MEASURING BRIDGE DEFLECTION AND DIFFERENTIAL MOVEMENT BETWEEN THE AXLE AND THE BODY OF A MOVING TEST VEHICLE WERE USED ALONG WITH THE MATHEMATICAL MODEL TO STUDY BRIDGE-VEHICLE INTERACTION. THE INSTRUMENTATION, TECHNIQUES, AND RESULTS ARE DESCRIBED AND ANALYZED. THE ACCURACY WITH WHICH DYNAMIC WHEEL LOAD TRANSDUCERS CAN BE USED TO PREDICT STATIC VEHICLE WEIGHTS IS ASSESSED THROUGH THE USE OF REGRESSION TECHNIQUES. THE ANALYSIS INDICATES THAT STATIC LOADS CAN BE ESTIMATED WITH SUFFICIENT ACCURACY FOR MANY TRAFFIC SURVEY PURPOSES, AND THAT THE LARGE SAMPLE SIZE, MADE FEASIBLE WITH NO INCONVENIENCE OR HAZARD TO TRAFFIC, INDICATES THE IN-MOTION WEIGHING AS A POTENTIAL SUBSTITUTE FOR LOADOMETER WEIGHING. /AUTHOR/

• Supplemental Notes:
  • 3 APP RES PROJ 3-8-67-108
• Corporate Authors:

  University of Texas, Austin

  Center for Highway Research, 200 West 21st Street
  Austin, TX  United States  78712
• Authors:
  • Al-rashid, N I
  • Lee, C E
  • Dawkins, W P
• Publication Date: 1972-5

Media Info

• Features: Figures; References; Tables;
• Pagination: 287 p.

Subject/Index Terms

• TRT Terms: Computer programs; Dynamics; Forecasting; Mathematical models; Motor vehicles; Regression analysis; Weight; Wheel loads
• Uncontrolled Terms: Dynamic characteristics
• Subject Areas: Data and Information Technology; Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00224211
• Record Type: Publication
• Report/Paper Numbers: No 108-1f
• Files: TRIS
• Created Date: May 7 1973 12:00AM