Title:
Behavior of Lap-Spliced Reinforcing Bars Embedded in High-Strength Concrete
Author(s):
Atorod Azizinamini, Rob Pavel, Erleen Hatfield, and S. K. Ghosh
Publication:
Structural Journal
Volume:
96
Issue:
5
Appears on pages(s):
826-835
Keywords:
bond (concrete to reinforcement); building codes; deformed reinforcement; high-strength concretes; reinforcing steels; splicing; struc-tural engineering
DOI:
10.14359/737
Date:
9/1/1999
Abstract:
Safety concerns and a lack of test data on the bond strength of deformed reinforcing bars embedded in high-strength concrete are reasons why the ACI 318 Building Code has imposed an arbitrary limit of 10,000 psi (69 MPa) in calculating the tension development length and the tension lap-splice length. This limitation was first introduced in the 1989 edition of ACI 318. In an attempt to evaluate the impact of this limitation and develop provisions for its removal, a two-phase investigation was carried out at the University of Nebraska-Lincoln. This paper provides a complete summary of the experimental investigations conducted in both phases of the project. Phase I of the investigation was supported by the Port-land Cement Association, while Phase II was supported by the National Science Foundation. During the two phases, 70 beam speci-mens with tension reinforcement splices were tested. The parameters studied included: bar size, length and deformation type of the reinforc-ing bars, amount of transverse reinforcement over the splice length, casting position, and concrete compressive strength. Results of the investigation are used to discuss observed differences in how reinforc-ing bars in tension develop in normal and high-strength concretes (HSCs), to develop hypotheses to explain these differences, and to sug-gest conditions for removal of the current concrete compressive strength limitation of the ACI 318 Building Code, which applies to the calcula-tion of tension development length and tension splice length. Develop-ment of code language provisions for removal of the current limitation, is discussed elsewhere. In this paper, HSC is defined as concrete with compressive strength exceeding 10,000 psi (69 MPa).