Effects of Bar Deformation and Concrete Strength on Bond on Reinforcing Steel to Concrete

Hideki Kimura and James O. Jirsa


Current ASTM deformation requirements for reinforcement are based on research conducted over 30 years ago. Since that time increases in steel and concrete strengths have resulted in a trend to design smaller and more congested structural members. Concrete strengths used today are two to three times greater than those in use when the current deformed bars were developed. The objective of this study is
(1) to seek improvements in deformed bar geometries which could reduce development length, and
(2) to provide technical data on bond between high strength concrete and reinforcing steel.
Existing data, especially recent work done in Japan, is reviewed prior to selecting deformation geometry (rib height, rib face angle and rib spacing).

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