NEW INVESTIGATIONS CONCERNING OVERLAPPING REINFORCEMENT LAPS

NEUE UNTERSUCHUNGEN AN UEBERGREIFUNGSSTOESSEN

THE REPORT CONCERNS THE RESULTS OF TWO SERIES OF TESTS: (1) FULLY STRESSED TENSION LAPS OF THE MAIN REINFORCEMENT OF BEAMS SUBJECT TO BENDING OF STEEL GRADE BST 42/50 RK AND CONCRETE GRADE BN 250. (2) LAPS IN BINDERS SUBJECT TO TRANSVERSE SHEAR. IN THE CASE OF THE FIVE BENDING TESTS THE VARIABLES WERE THE BAR DIAMETER, THE CLEAR SPACING OF THE LAPS AND THE LENGTH OF THE OVERLAP. OBSERVATIONS AND MEASUREMENTS INCLUDED THE CONCRETE STRAIN, STRAIN IN THE MAIN AND TRANSVERSE REINFORCEMENT, SLIP OF BARS IN THE CONCRETE, SPALLING OF THE CONCRETE COVER, DEFLEXION AND CRACK PATTERN. THE FINAL EVALUATION OF THE VOLUMINOUS DATA IS STILL IN PROGRESS. IT IS HOWEVER RECOGNISABLE THAT AT WORKING LOAD THE LOAD TRANSFER TAKES PLACE MAINLY AT THE ENDS OF THE LAPPED BARS, WHEREAS AT FAILURE OF THE LAP CONSIDERABLE BOND STRESSES OCCUR ALSO IN THE CENTRE OF THE LAP LENGTH. IN THE CASE OF THE SHEAR TESTS THE INVESTIGATION CENTRED ON THE DETERMINATION OF THE LAP LENGTHS REQUIRED FOR HAT STIRRUPS OF WELDED MESH GRADE BST 50/55 RK TO PROVIDE ADEQUATE ULTIMATE STRENGTH AND SATISFACTORY BEHAVIOUR UNDER WORKING LOAD. THE CONCRETE STRENGTH WAS BETWEEN 300 AND 340 KP/CM2. THE TESTS COVERED SHEAR ZONE 2. VARIABLES WERE THE LAP LENGTHS, THE DIAMETER AND SPACING OF THE WIRES. ALL THREE TESTS PROVIDED ADEQUATE ULTIMATE STRENGTH. THE CRACK WIDTHS UNDER WORKING LOADS EXCEEDED 0,1 MM FOR SHORT LAP LENGTHS. THE INFLUENCE OF THE BAR SPACING WAS ALSO NOTED IN THIS RESPECT. BECAUSE OF THE SLIP THE STRESSES IN LAPPED BINDERS ARE LOWER THAN IN BINDERS WITHOUT LAPS.

  • Authors:
    • KUPFER, H
  • Publication Date: 1976

Language

  • German

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 01292652
  • Record Type: Publication
  • Source Agency: Bundesanstalt für Straßenwesen (BASt)
  • Files: ITRD
  • Created Date: Nov 21 2010 3:36AM