LOAD AND DEFLECTION CHARACTERISTICS OF DOWELS IN TRANSVERSE JOINTS OF CONCRETE PAVEMENTS

LABORATORY TESTS WERE MADE ON SINGLE DOWELS ENCASED IN CONCRETE TO OBSERVE THE CHARACTERISTICS OF FAILURE AND THE RATE OF DEFLECTION OF TRANSVERSELY LOADED DOWELS IN CONCRETE. THE RATE AT WHICH THE CONCRETE REACTS UNDER A DEFLECTING DOWEL IS CALLED MODULUS OF DOWEL REACTION. LOADED 1/2 IN. FROM THE FACE OF THE CONCRETE, 3/4-IN. HARD GRADE DOWELS FAILED AT 6000 LB. DOWEL LOAD AND 1-IN. INTERMEDIATE GRADE DOWELS AT 9000 LB. DOWEL LOAD, WHEN ENCASED IN 3000 LB. PER SQ. IN. CONCRETE. WARNING OF FAILURE IS GIVEN BY SURFACE SPALLING UNDER THE DOWEL, COMMENCING AT LOADS CONSIDERABLY LESS THAN THE ULTIMATE. ULTIMATE FAILURE IS ACCOMPANIED BY CRUSHING OF THE CONCRETE IMMEDIATELY UNDER THE DOWEL. THE 3/4-IN. DOWELS ARE ALL PERMANENTLY BENT AT FAILURE. RELATIONSHIP OF DOWEL STRENGTH TO THE STRENGTH OF THE CONCRETE AND TO THE YIELD POINT OF THE STEEL IS INDICATED. A REASONABLE VALUE FOR THE MODULUS OF DOWEL REACTION FOR 3/4-IN. AND 1-IN. GREASED DOWELS IN 6-AND 7- IN. CONCRETE PAVEMENTS ON YIELDING SUBGRADE IS DEDUCED FROM THESE TESTS TO BE 300 TIMES THE UNIT CRUSHING STRENGTH OF CYLINDERS OF THE CONCRETE. /AUTHOR/