FLEXURAL CRACK WIDTH AT THE BARS IN REINFORCED CONCRETE BEAMS

RESULTS ARE PRESENTED OF AN INVESTIGATION INTO THE RELATIONSHIP BETWEEN THE WIDTH OF SURFACE CRACKS ON REINFORCED CONCRETE BEAMS AND THE WIDTH OF THE CRACKS AT LOADED BEAMS. AFTER HARDENING OF THE EPOXY, THE BEAMS WERE SAWED INTO SEGMENTS AND THE WIDTH OF CRACKS WAS DETERMINED WITH MICROSCOPES. VARIABLES IN THE STUDY WERE: CONCRETE COVER, BAR SIZE, STRESS LEVEL AND CONCRETE STRENGTH. THE MAJOR FINDINGS OF THE STUDY WERE AS FOLLOWS: (1) THE CRACK SPACING AND CRACK WIDTH AT ANY LEVEL VARY FROM AVERAGE VALUES BY AT LEAST PLUS OR MINUS 50 PERCENT, (2) STEEL STRESS WAS THE MOST IMPORTANT VARIABLE INFLUENCING CRACK WIDTH AT THE BAR: AT 20 KSI STEEL STRESS, AVERAGE CRACK WIDTH AT THE BAR SURFACE RANGED DOWNAWARD FROM 0.001 INCHES, AT 30 KSI STEEL STRESS, THE CRACK WIDTH AT THE BAR WAS ABOUT 50 PERCENT GREATER THAN THE 20 KSI WIDTHS, EXCEPT THAT WHEN THERE WAS A COVER OF 3 INCHES, THE AVERAGE CRACK WIDTHS AT THE BARS WERE 0.0029 INCHES. (3) IN GENERAL IT CAN BE SAID THAT CRACK WIDTHS AT THE BEAM TENSION FACE VARIED LINEARLY WITH CONCRETE COVER, & (4) THE RATIO OF CRACK WIDTH AT THE BAR TO THAT AT THE SURFACE VARIED FROM 0.10 TO 0.31, BEING LARGEST IN A SHALLOW MEMBER WITH CLEAR COVER OF 0.75 INCHES. /BPR/

• Supplemental Notes:
  • Hpr-1/5/, STATE-3-5-66-102
• Corporate Authors:

  University of Texas, Arlington

  Arlington, TX  United States  76010

  Texas State Department of Highways & Public Transp

  11th and Brazos Streets
  Austin, TX  United States  78701

  Bureau of Public Roads /US

  400 7th Street, SW
  Washington, DC  United States  20590
• Authors:
  • Husain, S I
  • Ferguson, P M
• Publication Date: 1968-6

Subject/Index Terms

• TRT Terms: Beams; Concrete; Cracking; Epoxides; Flexure; Material reinforcement; Reinforced concrete; Spacing; Steel; Stresses; Surfaces; Width
• Uncontrolled Terms: Concrete beams; Injection; Surface cracks
• Old TRIS Terms: Cover; Epoxy
• Subject Areas: Bridges and other structures; Highways; Materials;

Filing Info

• Accession Number: 00207876
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS, STATEDOT
• Created Date: Aug 28 1994 12:00AM