FULL SCALE MODEL TESTS TO DETERMINE DECREASE IN PRESTRESSING FORCE AS A RESULT OF THE OBSTRUCTION OF FRICTION

GROSSE MODELLVERSUCHE ZUR ERMITTLUNG DES SPANNKRAFTABFALLS INFOLGE REIBUNGSBEHINDERUNG

A PROCEDURE FOR REALISTICALLY DETERMINING THE COEFFICIENT OF FRICTION FOR THE FRICTION OF PRESTRESSED MEMBERS HAD TO BE DEVELOPED FOR POST TENSIONING. IN PARTICULAR THE RELATION BETWEEN THE COEFFICIENT OF FRICTION OF THE PRESTRESSING FORCES AND THE DISPLACEMENTS BETWEEN THE PRESTRESSING STEELS AND THE SHEET-METAL SHEATH WAS TO BE EXAMINED. FULL SCALE MODEL TESTS WERE CARRIED OUT USING REAL 600 KN PRESTRESSED MEMBERS ABOUT 10 M LONG MADE OF THREE DIFFERENT TYPES OF PRESTRESSING STEEL. A NEW TESTING TECHNIQUE WAS DEVELOPED WHICH ENABLES THE STRESS PATHS OF BOTH LONG AND SHORT PRESTRESSING MEMBERS TO BE SIMULATED. THE STUDY OF THE EFFECT OF THE PRESSING FORCES TOOK PLACE WITH CONSTANT RADII OF CURVATURE OF R = 4, 8 AND 24 M. THE MOST IMPORTANT RESULT ESTABLISHED WAS THAT THE COEFFICIENT OF FRICTION IS NOT CONSTANT OVER THE LENGTH OF A PRESTRESSING MEMBER. FOR SECTIONS HAVING SMALL DISPLACEMENT PATHS THE COEFFICIENT OF FRICTION IS HIGHER THAN IN SECTIONS HAVING LARGE DISPLACEMENT PATHS. THIS INCREASE IN THE VALUE OF THE COEFFICIENT OF FRICTION DEPENDS ON THE PRESSING FORCES. FOR PRESTRESSING MEMBER SECTIONS HAVING DISPLACEMENT PATHS OF MORE THAN 40 MM HOWEVER, THE RESULT IS A UNIFORM COEFFICIENT OF FRICTION WHICH IS INDEPENDENT OF THE PRESSING FORCES, AND WHICH IS SIGNIFICANTLY LOWER THAN THAT OF PRESTRESSING STEELS HAVING SMALLER DISPLACEMENT PATHS. THE TESTS ALSO PROVIDED INFORMATION ON THE EFFECTS OF REPEATING THE STRESSING, OMITTING IT, AND ON THE SO-CALLED CLAMPING COEFFICIENT.

    Language

    • German

    Project

    • Status: Completed
    • Contract Numbers:

      ITRD 15.004 R 73 D

    • Sponsor Organizations:

      BUNDESMINISTER FUER VERKEHR (FEDERAL MINISTER OF TRANSPORT)

      POSTFACH 20 01 00
      BONN,   DEUTSCHLAND BR  D-5300
    • Project Managers:

      Trost, H

    • Performing Organizations:

      TECHNISCHE HOCHSCHULE AACHEN, INST. FUER MASSIVBAU (TECHNICAL UNIVERSITY OF AACHEN, INSTITUTE FOR MASSIVE CONSTRUCTION)

      MIES-VAN-DER-ROHE-STRASSE
      AACHEN,   DEUTSCHLAND BR  D-5100
    • Start Date: 19730000
    • Expected Completion Date: 0
    • Actual Completion Date: 19780000
    • Source Data: ITRD D701811

    Subject/Index Terms

    Filing Info

    • Accession Number: 01294428
    • Record Type: Research project
    • Source Agency: Bundesanstalt für Straßenwesen (BASt)
    • Contract Numbers: ITRD 15.004 R 73 D
    • Files: ITRD
    • Created Date: Nov 21 2010 4:34AM