HISTORY OF TENSION IN BOLTS CONNECTING LARGE JOINTS

THIS REPORT DESCRIBES AN EXPERIMENTAL STUDY OF THE CHANGES IN BOLT TENSION IN HIGH-STRENGTH A325 AND A490 BOLTS CONNECTING A440 AND CONSTRUCTIONAL ALLOY STEEL JOINTS. UNTIL MAJOR SLIP OCCURRED IN THE LARGE BOLTED JOINTS, HIGH -STRENGTH STEEL BOLTS LOST ONLY A SMALL AMOUNT OF THEIR INITIAL TENSION. THIS LOSS WAS DUE TO THE PLATE CONTRACTION CAUSED BY THE POISSON EFFECT. AFTER SLIP THE BOLTS CAME INTO BEARING, AND THE VARIATIONS IN BOLT TENSION BECAME MORE PRONOUNCED. FOR BOLTS WITH A 4 IN. GRIP THE BOLT TENSION DECREASED WITH AN INCREASE IN JOINT LOAD BEYOND THE SLIP LOAD. AS THE JOINT LOAD APPROACHED ITS ULTIMATE VALUE, HOWEVER, THE BOLTS AT THE LAP PLATE END BEGAN TO SHOW AN INCREASE IN TENSION. THIS WAS BROUGHT ABOUT BY THE OUTWARD PRYING ACTION OF THE LAP PLATE. THESE RESULTS SHOWED THAT THE LOAD TRANSFERRED BY FRICTION, AT THE ULTIMATE JOINT STRENGTH, WAS NEGLIGIBLE. FOR BOLTS WITH AN 8 IN. GRIP THE BOLT TENSION INCREASED AS THE JOINT WAS LOADED BEYOND THE SLIP LOAD. THIS INCREASE WAS CAUSED BY BENDING OF THE BOLTS, AND INDICATED THAT SOME LOAD WAS BEING TRANSFERRED BY FRICTIONAL RESISTANCE IN THE INTERIOR OF THE JOINT. HOWEVER, BECAUSE OF THE LAP PLATE PRYING PHENOMENON THERE WAS A CLEAR SEPARATION OF THE FAYING SURFACES NEAR THE JOINT END AND THE BOLT TENSION WAS NOT COMPLETELY INDICATIVE OF THE NORMAL FORCE ACTING ON THE FAYING SURFACE. FOR ALL JOINTS IT WAS FOUND THAT THE BOLTS AT THE LAP PLATE ENDS, BEING UNDER A HIGHER COMBINED SHEAR AND TENSION LOADING THAN THE BOLTS AT THE MAIN PLATE END, WERE USUALLY THE FIRST TO FAIL. /AUTHOR/

• Supplemental Notes:
  • Hps-hpr1/2/, BPR-2, PDH-360, DEC64
• Corporate Authors:

  Lehigh University

  Bethlehem, PA  United States  18015
• Authors:
  • Wallaert, J J
  • Sterling, G H
  • Fisher, J W
• Publication Date: 1964-12

Subject/Index Terms

• TRT Terms: Alloy steel; Bolted joints; Bolts; Construction joints; Contraction; Experiments; Friction; Joints; Loads; Poisson ratio; Structural analysis; Structural mechanics; Structural plates; Tension; Tension tests
• Uncontrolled Terms: A325 bolts; Loading; Plates; Structural behavior
• Old TRIS Terms: A440 joints; A490 bolts; High strength bolts; Joint; Poissons ratio
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00207736
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS
• Created Date: Oct 1 1994 12:00AM