Mechanism Analysis for Concrete Breakout Capacity of Single Anchors in Tension

A correct estimation of the concrete breakout capacity of anchors under tensile loads would permit the nominal anchor strength to be controlled by ductile yielding. This paper develops a numerical technique based on the theory of plasticity to predict an optimum geometry of the failure surface and concrete breakout capacity of single anchors away from edges under tensile loads. In this technique, concrete is regarded as a rigid, perfectly plastic material obeying a modified coulomb failure criteria with effective compressive and tensile strengths. The failure mode is idealized as an assemblage of two rigid blocks separated by failure surfaces of displacement discontinuity. Minimization of the collapse load predicted by the energy equation produces the optimum shape of the failure surface geometry. A simplified solution is developed by approximating the failure surface as two straight lines. The effect of different parameters on the concrete breakout capacity of anchors is reviewed using the developed mechanism analysis, ACI 318-05, and test results of 501 cast-in-place and 442 post-installed anchor specimens. The shape of failure surface and concrete breakout capacity of anchors predicted by the mechanism analysis are significantly affected by the ratio between effective tensile and compressive strengths of concrete. For anchors installed in concrete having a low ratio between effective tensile and compressive strengths, a larger horizontal extent of failure planes in concrete surface is predicted by the mechanism analysis than recommended by ACI 318-05. Experimental concrete breakout capacity of anchors is closer to the prediction obtained from the mechanism analysis than ACI 318-05. ACI 318-05 provisions for anchors significantly underestimate the breakout capacity of cast-in-place and post-installed anchors having effective embedment depths exceeding 200 and 80 mm, respectively, installed in concrete of compressive strength larger than 50 MPa (7250 psi). The experiments also suggest that concrete breakout capacity of anchors slightly increases with the increase of the ratio of head diameter to effective embedment depth anchors.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/13846957
• Authors:
  • Yang, Keun-Hyeok
  • Ashour, Ashraf F
• Publication Date: 2008-9

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 609-616
• Serial:
  • ACI Structural Journal
  • Volume: 105
  • Issue Number: 4
  • Publisher: American Concrete Institute (ACI)
  • ISSN: 0889-3241
  • Serial URL: http://www.concrete.org/PUBS/JOURNALS/SJHOME.ASP

Subject/Index Terms

• TRT Terms: Anchors (Structural connectors); Compressive strength; Concrete; Ductility; Failure; Geometry; Plasticity; Tensile strength; Tension
• Uncontrolled Terms: Breakout capacity
• Subject Areas: Bridges and other structures; Highways; Materials; I20: Design and Planning of Transport Infrastructure; I32: Concrete;

Filing Info

• Accession Number: 01113006
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 21 2008 8:48AM