Guide for Lap Splice and Development Length of High Relative Rib Area Reinforcing Bars in Tension and Commentary

Description

This guide is provided to help designers take advantage of higher bond strength exhibited by high relative rib area bars(Darwin and Graham 1993; Darwin et al. 1996a; Zuo and Darwin 1998) in the calculation of tension lap splice length and development length of bar reinforcement. It includes expressions for development and lap splice length applicable only for high relative rib area bars. This document has been updated to reflect improvements to the provisions of ACI408.3-01 (ACI Committee 408 2001) proposed by Darwin etal. (2005).

Because experimental data are available only to evaluate the development and lap splice lengths of straight high relative rib area bars in tension, the integrity of high relative rib area bars in compression or as hooked bars intension should be evaluated using appropriate Chapter 12provisions of ACI 318-08 (ACI Committee 318 2008).To use this guide, ASTM A615/A615M for carbon-steel reinforcing bars should have the supplementary require-ments imposed by the “Recommended Supplement to ASTM A615/A615M for High Relative Area Bars” that is appended to this document. With modifications to the section reference numbers, this supplement can be adapted for use with ASTM A706/A706M for low-alloy steel reinforcing bars.