COMPUTATION OF STRESSES IN CONCRETE ROADS

COMPUTATION OF STRESSES IN CONCRETE ROADS MAY BE OBTAINED BY ASSUMING THE SLAB TO ACT AS A HOMOGENEOUS ISOTROPIC ELASTIC SOLID IN EQUILIBRIUM AND BY ASSUMING THE REACTIONS OF THE SUBGRADE TO BE VERTICAL ONLY AND TO BE PROPORTIONAL TO THE DEFLECTIONS OF THE SLAB. WITH THESE ASSUMPTIONS, THE ANALYSIS IS REDUCED TO A PROBLEM OF MATHEMATICAL THEORY OF ELASTICITY. THE REACTION OF THE SUBGRADE PER UNIT OF AREA AT ANY GIVEN POINT IS EXPRESSED AS A COEFFICIENT CALLED THE MODULUS OF SUBGRADE TIMES THE DEFLECTION AT THE POINT. THIS COEFFICIENT IS A MEASURE OF THE STIFFNESS OF THE SUBGRADE. A FORMULA IS GIVEN FOR THE RADIUS OF RELATIVE STIFFNESS. USING THESE MATHEMATICAL FORMULAS AND RELATIONSHIPS, THREE CASES OF LOADING WERE INVESTIGATED. THESE CASES ARE: (1) A WHEEL LOAD ACTS CLOSE TO A RECTANGULAR CORNER OF A LARGE PANEL OF THE SLAB, (2) THE WHEEL LOAD IS AT A CONSIDERABLE DISTANCE FROM THE EDGES, AND (3) THE WHEEL LOAD IS AT THE EDGE, BUT AT A CONSIDERABLE DISTANCE FROM ANY CORNER. THE QUESTION OF BALANCED DESIGNS FOR THE THREE CASES OF LOADING ARE ANALYZED AND TESTED BY THE USE OF TABLES. DEFLECTIONS ARE MATHEMATICALLY DETERMINED WHICH ARE DUE TO MORE THAN ONE WHEEL. TABLES ARE GIVEN FROM WHICH CORRESPONDING CRITICAL STRESSES MAY BE COMPUTED. CERTAIN INFLUENCES WERE LEFT OUT OF CONSIDERATION WHEN USING TABLES AND DIAGRAMS, ESPECIALLY THE FOLLOWING: (1) VARIATIONS OF TEMPERATURE, AND OTHER CAUSES FOR TENDENCY TO CHANGE VOLUME, (2) THE GRADUAL DIMINISHING OF THE THICKNESS FROM THE EDGE TOWARD THE INTERIOR, (3) LOCAL SOFT OR HARD SPOTS IN THE SUBGRADE, (4) HORIZONTAL COMPONENTS OF THE REACTIONS OF THE SUBGRADE, AND (5) THE DYNAMIC EFFECT, EXPRESSED IN TERMS OF THE INERTIA OF THE PAVEMENT AND SUBGRADE. THE HORIZONTAL COMPONENTS OF THE REACTIONS OF THE SUBGRADE, WHICH ARE DUE TO FRICTION, MAY HAVE A STRENGTHENING INFLUENCE, ESPECIALLY AT SOME DISTANCE FROM THE EDGES, BY CAUSING A DOME ACTION IN THE PAVEMENT. WITH KNOWN VALUES OF THE MAXIMUM PRESSURE DEVELOPED BETWEEN THE TIRE AND THE PAVEMENT, THE EFFECT OF THE INERTIA OF THE PAVEMENT MAY POSSIBLY BE EXPRESSED APPROXIMATELY IN TERMS OF AN INCREASED VALUE OF THE MODULUS OF SUBGRADE REACTION.

• Record URL:
  https://onlinepubs.trb.org/Onlinepubs/hrbproceedings/5/5-008.pdf
• Supplemental Notes:
  • Vol 5, Part I, PP 90-112, 11 FIG, 4 TAB. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
• Authors:
  • WESTERGAARD, H M
• Publication Date: 1926

Media Info

• Media Type: Digital/other
• Monograph Title: Proceedings of the Fifth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 3-4, 1925. Part I: Reports of Research Committees and of Special Investigations
• Serial:
  • Highway Research Board Proceedings
  • Volume: 5
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Calculation; Concrete pavements; Deflection; Dynamics; Elasticity (Mechanics); Isotropic materials; Mathematical analysis; Modulus of elasticity; Pavements; Slabs; Stiffness; Stresses; Subgrade (Pavements); Tables (Data); Thickness; Wheel loads
• Uncontrolled Terms: Computation; Dynamic characteristics; Pavement thickness; Wheel load distribution
• Old TRIS Terms: Elastic theory; Isotropic mass; Pavement deflection
• Subject Areas: Highways; Pavements;

Filing Info

• Accession Number: 00206779
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Jun 18 1994 12:00AM