Title: Development Length of Unconfined Conventional and High-Strength Steel Reinforcing Bars

Author(s): Amr Hosny, Hatem M. Seliem, Sami H. Rizkalla, and Paul Zia

Publication: Structural Journal

Volume: 109

Issue: 5

Appears on pages(s): 655-664

Keywords: bond; development length; high-strength steel; reinforcement; splice length

DOI: 10.14359/51684043

Date: 9/1/2012

Abstract:
The development length equation specified by ACI 318-08 and the similar equation recommended by ACI 408R-03 are based on extensive test results using conventional reinforcement conforming to ASTM A615/A615M and A706/A706M. With the development of new ASTM A1035/A1035M high-strength steel reinforcement, several studies have been conducted to examine whether the current equations are applicable for the new high-strength reinforcing steel. These studies have shown that the current equations could, in some cases, overestimate the bond strength of high-strength steel bars. This paper proposes a new equation for the bond strength of unconfined reinforcing bars for all three types of steel. The proposed equation for high-strength steel is compared to extensive test data reported in the literature and is found to be more accurate than ACI 318-08 and ACI 408R-03 equations specified for conventional reinforcement.