BOND RESISTANCE OF HIGH ELASTIC LIMIT STEEL BARS, SERIES OF 1937

THE 1936 RECONNAISSANCE PULLOUT BOND TESTS RAISED IMPORTANT QUESTIONS, SOME OF WHICH CHALLENGED VENERABLE CONCEPTS. THE COMPREHENSIVE TESTS REPORTED HERE BEAR OUT INDICATIONS THAT: (1) BOND RESISTANCE DOES NOT INCREASE IN PROPORTION TO THE INCREASE IN COMPRESSIVE STRENGTH OF CONCRETE,(2) THE TOTAL BOND RESISTANCE OF A PLAIN BAR INCREASES WITH ADDED LENGTH OF EMBEDMENT UP TO SOME LIMITING LENGTH (ABOUT 24 DIAMETERS FOR THESE TESTS) ABOVE WHICH THERE IS LITTLE OR NO GAIN FROM ADDED LENGTH OF EMBEDMENT, (3) THE UNIT BOND RESISTANCE FOR A PLAIN BAR DECREASES AS THE LENGTH OF EMBEDMENT INCREASES FOR ALL LENGTHS OF EMBEDMENT, AND (4) DEFORMED BARS SLIP INITIALLY AT BOND STRESSES SOMEWHAT ABOVE THOSE FOR PLAIN BARS AND INVARIABLY FAIL ULTIMATELY BY SPLITTING THE CONCRETE. AMONG THE SEVERAL MORE OR LESS NEW FINDINGS ARE: (5) THAT PULLOUT SPECIMENS CAN BE MADE TO GIVE TRUE INDICATIONS OF BOND RESISTANCE OF SIMILAR BARS IN BEAMS, (6) THAT THE INCREASE OF MAXIMUM BOND RESISTANCE OVER THAT AT INITIAL SLIP, FOR PLAIN BARS BECOMES UNIFORMLY LESS AS THE STRESS IN THE BAR INCREASES AND AT YIELD POINT STRESS IS NO APPRECIABLE INCREASE IN BOND ABOVE THAT AT INITIAL SLIP, AND (7) THE PROGRESSIVE NATURE OF BOND FAILURE IS SHOWN BY MEASURED STRAINS AT THE COMPRESSIVE CONCRETE SURFACES OF BEAM AND PULLOUT SPECIMENS. THE PRESENT TESTS COVER TWO STRENGTHS OF CONCRETE (3,000 AND 5,000 P.S.I AT 28 DAYS); 3 SIZES OF PLAIN AND DEFORMED HIGH ELASTIC LIMIT STEEL BARS (3/8, 5/8 AND 3/4); SEVERAL DEPTHS OF CONCRETE COVER OVER DEFORMED BARS; PULLOUT SPECIMENS WITH EMBEDMENTS RANGING FROM 3 TO 24 IN. (LENGTH DIAMETER RATIOS FROM 4 TO 64); BEAM-TYPE SPECIMENS WITH STEEL PERCENTAGES RANGING FROM 0.552 TO 2.76. THESE GAVE FAILURE IN BOND AND/OR DIAGONAL TENSION, TENSION IN THE STEEL, AND ONE COMPRESSIVE CONCRETE FAILURE. THESE DATA SUPPLY A FACTUAL BASIS FOR DETERMINATION OF FACTORS OF SAFETY AGAINST EACH OF THE SEVERAL TYPES OF FAILURE. FACTORS OF SAFETY AGAINST FAILURE BY BOND AND/OR DIAGONAL TENSION ARE SOMEWHAT HIGHER THAN THOSE AGAINST FAILURE BY TENSION (YIELD POINT STRESS) IN THE STEEL. ONLY A LIMITED PORTION OF THE STRAIN DATA SECURED IS PRESENTED. /AUTHOR/ /AUTHOR/

• Record URL:
  https://onlinepubs.trb.org/Onlinepubs/hrbproceedings/17/17Pt1-010.pdf
• Supplemental Notes:
  • Vol 17, ParT I, PP 150-186, 13 FIG, 5 TAB, 16 PHOT, 12 REF; part of Report of Project Committee on the Use of High Elastic Steel as Reinforcement for Concrete. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
• Authors:
  • Gilkey, H J
  • Chamberlin, S J
  • Beal, R W
• Publication Date: 1938

Media Info

• Media Type: Digital/other
• Monograph Title: Proceedings of the Seventeenth Annual Meeting of the Highway Research Board Held at Washington, D.C. November 30, December 1, 2, 3, 1937. Part I
• Serial:
  • Highway Research Board Proceedings
  • Volume: 17
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Anchoring; Bars (Building materials); Beams; Bond strength (Materials); Bonding; Compressive strength; Concrete; Deformed bars; Elastic limit; Failure; Pull out test; Steel; Stresses; Tension; Testing
• Old TRIS Terms: Embedments (Concrete); Pullout
• Subject Areas: Bridges and other structures; Highways; Materials;

Filing Info

• Accession Number: 00213787
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Aug 15 1971 12:00AM