THE STRENGTH OF ANCHOR BARS: A REEVALUATION OF TEST DATA ON DEVELOPMENT LENGTH AND SPLICES

An equation has been developed for calculating lengths of lap splices of deformed bars from a nonlinear regression analysis of test results of beams with lap splices. It reflects the effect of length, cover, spacing, bar diameter, concrete strength, transvers reinforcement, and moment gradient on the strength of lap splices. The equation is also applicable in determining basic development lengths. Based on the equation developed, design recommendations are proposed for development lengths and lap splices and compared with AASHTO Interim Specifications for Bridges, 1974. The comparison shows that for the most unfavorable splice conditions (a clear cover of 1-1/2 in. on sides or bottom, splices with no transverse reinforcement, all bars spliced in a region of maximum moment, and bar spacing less than 6 in. on centers) AASHTO provisions overestimate lap lengths by 11 percent for #6, 16 percent for #8, and 25 percent for #11 bars. If cover is increased to 3 in. or transverse reinforcement is added, the splice length of large bars may be reduced by as much as 60 percent over that required by present AASHTO provisions. Furthermore, the equations governing development length are essentially the same as those for splice length. /FHWA/

  • Supplemental Notes:
    • Sponsored by Texas State Department of Highways and Public Transportation in cooperation with FHWA.
  • Corporate Authors:

    University of Texas, Austin

    Center for Highway Research, 200 West 21st Street
    Austin, TX  USA  78712

    Federal Highway Administration

    Engineering Research and Development Bureau, 1200 New Jersey Avenue, SE
    Washington, DC  USA  20590

    Texas State Department of Highways & Public Transp

    P.O. Box 5051
    Austin, TX  USA  78763
  • Authors:
    • Orangun, C O
    • Jirsa, James O
    • Breen, J E
  • Publication Date: 1975-1

Media Info

  • Pagination: 90 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00130584
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA-RD-75-S0422 Final Rpt.
  • Contract Numbers: 3-5-72-154
  • Files: NTIS, TRIS, USDOT, STATEDOT
  • Created Date: Mar 29 1976 12:00AM