Comparison of Bond Strength of Steel Bars in Normal- and High-Strength Concrete

Abstract

A comparative analytical study of the average bond strength at failure of reinforcing bars embedded in unconfined normal-strength concrete (NSC) and high-strength concrete (HSC) is undertaken. The analysis makes use of an experimentally derived local bond stress-slip model and considers the progressive bond deterioration along the development/splice length with the increase in bar force. Results of the average bond strength (or development/splice strength) predicted by the analysis showed excellent agreement with experimental data for both NSC and HSC. The analysis predicted a highly nonuniform bond stress distribution at bond failure along the development/splice length, particularly for HSC. Below a certain limit of the development/splice length (about 15-20db), the average bond strength at failure, normalized to fc′1/2, is larger for HSC as compared to NSC. However, as the development length increases beyond this limit, the normalized bond strength of HSC becomes progressively smaller than that of NSC. ...