EXPERIENCE WITH SHEAR REINFORCEMENT IN REINFORCED CONCRETE PIPE

IT HAS LONG BEEN REALIZED THAT AN UPPER LIMIT EXISTS FOR THE STRENGTH OF LARGE PIPE IN A THREE-EDGE-BEARING TEST. THIS BEARING TEST PRODUCES HIGH SHEARING STRESSES IN THE WALL OF A PIPE. THE MAXIMUM TEST LOAD THAT A PIPE CAN CARRY IS LIMITED LARGELY BY THE RESISTANCE OF THE CONCRETE ALONE TO A DIAGONAL TENSION FAILURE. THE DEMAND FOR HIGHER PIPE STRENGTHS DEVELOPED A SPECIAL DESIGN BASED ON AN INCREASED WALL THICKNESS. THIS PROVIDES MORE CONCRETE TO CARRY THE DIAGONAL TENSION DEVELOPED IN THE THREE-EDGE-BEARING TEST. HOWEVER, FOR LARGER DIAMETERS INCREASING THE WALL THICKNESS MAY MEAN A CONSIDERABLE WEIGHT INCREASE. THEREFORE, TO CARRY THE DIAGONAL TENSION STRESSES, SHEAR REINFORCEMENT MUST BE PROVIDED IN THE PIPE WALL. THE USE OF SHEAR REINFORCEMENT IS REVIEWED. TO BE EFFECTIVE, SHEAR REINFORCEMENT MUST BE POSITIVELY ANCHORED TO THE INSIDE CAGE OF THE PIPE REINFORCEMENT. USUALLY THIS ANCHORAGE IS BY HOOKING OR BENDING THE TIE OR STIRRUP AROUND THIS REINFORCING. THE EFFECT OF SHEAR REINFORCEMENT ON CRACK STRENGTH OF REINFORCED CONCRETE PIPE IS CONTROVERSIAL. SOME TESTS HAVE SHOWN EXCEPTIONALLY HIGH CRACKING STRENGTHS WHEN SHEAR REINFORCEMENT WAS USED. IN OTHER TESTS, CRACKING STRENGTHS HAVE BEEN SURPRISINGLY LOW RELATIVE TO THE ULTIMATE STRENGTHS OBTAINED. PIPE REINFORCED FOR SHEAR HAS ALWAYS BEEN DESIGNED WITH LARGE AREAS OF TENSION STEEL. TESTS HAVE SHOWN THAT IF A STAGGERED PATTERN OF PLACING THE SHEAR STEEL IS USED, A BETTER CRACK PATTERN RESULTS EVEN WITH A SINGLE HEAVY CAGE. THE VALUE OF THE IMPERFECT TRENCH METHOD OF INSTALLATION HAS BEEN CLEARLY DEMONSTRATED. THE EFFECTIVENESS OF SHEAR REINFORCEMENT IN THE FIELD HAS NEITHER BEEN PROVEN NOR DISPROVEN.

  • Supplemental Notes:
    • Vol 39, pp 385-388, 3 FIG, 1 REF
  • Authors:
    • Hendrickson, J G
  • Publication Date: 1960

Media Info

  • Monograph Title: Proceedings of the Thirty-Ninth Annual Meeting of the Highway Research Board, Washington, D.C., January 11-15, 1960
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00209482
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 29 1971 12:00AM