FRICTIONAL RESISTANCE UNDER CONCRETE PAVEMENTS AND RESTRAINT STRESSES IN LONG REINFORCED SLABS

TEMPERATURE CONTRACTION OF SHORT PAVEMENT SLABS IS NOT GREATLY DIMINISHED BY FRICTIONAL-TENSION STRESS. BUT LONG PAVEMENT SLABS, AS USED IN CONTINUOUSLY REINFORCED CONCRETE PAVEMENTS, ACTIVELY CONTRACT AND EXPAND ONLY FOR SOME HUNDREDS OF FEET NEAR EACH END. THE LENGTH OF ACTIVELY MOVING ENDS AND THE MOVEMENTS ARE RELATED TO THERMAL CHANGE, TO FRICTION COEFFICIENT, AND TO THE MODULUS OF ELASTICITY OF THE PAVEMENT. SIMPLE MATHEMATICAL RELATIONS ARE SUGGESTED. THE FRICTION COEFFICIENT BEFORE SLIDING ON THE SUBGRADE IS NOT CONSTANT; IN TESTS, LARGE MOVEMENTS OF LONG SLABS HAVE BEEN OBSERVED WITHOUT SLIDING AT FRICTIONAL RESISTANCE PROPORTIONATE TO THE ROOT OF THE MOVEMENT. THE OVERALL MODULUS OF ELASTICITY OF THE REINFORCED PAVEMENT IS MUCH DECREASED BELOW THAT FOR CONCRETE ALONE DUE TO CLOSELY SPACED OPEN CRACKS. OBSERVED BEHAVIOR OF CONTINUOUSLY REINFORCED PAVEMENTS AGREES WELL WITH THAT COMPUTED FOR FRICTIONAL RESISTANCE INCREASING AT A RELATIVELY LOW RATE WITH MOVEMENT. FULLY RESTRAINED CENTRAL PARTS OF CONTINUOUSLY REINFORCED CRACKED PAVEMENTS ARE SUBJECT TO TEMPERATURE RESTRAINT STRESSES IN ACCORDANCE WITH STRESS FORMULAS WHICH TAKE INTO CONSIDERATION THE MECHANICS OF CONCRETE-STEEL BOND. APPLICABLE BOND BEHAVIOR OF AVAILABLE REINFORCING STEEL IS SUGGESTED FROM TESTS. STEEL STRESS INCREASES WITH CRACK SPACING AND BOND RESISTANCE NEAR CRACKS. CONCRETE STRESS BETWEEN CRACKS INCREASES WITH INCREASING STEEL AREA AND STEEL STRESS AT CRACK. CYCLIC CRACK WIDENING IS ONLY PARTIALLY PREVENTED BY THE STEEL, BUT FOR TYPICAL CLOSE CRACK SPACING, THE OPENING AT EACH CRACK IS SMALL. RESTRAINT STRESSES INCREASE AT A MUCH LOWER RATE THAN TEMPERATURE DROP. STRESSES FOR SEASONAL TEMPERATURE CHANGE ARE ONLY SLIGHTLY GREATER THAN FOR DAILY TEMPERATURE DROP. SEASONAL INCREASE APPEARS TO BE NONEXISTENT IN PAVEMENTS UP TO 1,000 FEET LONG, BECAUSE OF ABSENCE OF FRICTIONAL RESISTANCE TO NORMALLY DEVELOPING SEASONAL CONTRACTION IN PAVEMENTS OF THAT LENGTH. RESTRAINT STRESSES IN CRACKED PAVEMENTS AGREE WITH THOSE COMPUTED ON THE BASIS OF RELATIVELY LOW FRICTIONAL RESISTANCE FOR DAILY ACTIVE SLAB ENDS. THE AVERAGE FRICTIONAL RESISTANCE INDICATED UNDER CONTINUOUSLY REINFORCED PAVEMENTS IS MUCH LOWER THAN THE VALUE COMMONLY PROPOSED FOR DESIGN OF DISTRIBUTED REINFORCEMENT IN CONVENTIONAL-LENGTH SLABS. /AUTHOR/

  • Supplemental Notes:
    • Vol 33, pp 167-184, 15 FIG, 6 REF
  • Authors:
    • Friberg, B F
  • Publication Date: 1954

Media Info

  • Monograph Title: Proceedings of the Thirty-Third Annual Meeting of the Highway Research Board, Washington, D.C., January 12-15, 1954
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00207334
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 22 1972 12:00AM