Title: Bond Properties of 1/2 in. Diameter Strand

Author(s): A. D. Edwards and A. Picard

Publication: Journal Proceedings

Volume: 69

Issue: 11

Appears on pages(s): 684-689

Keywords: beams (supports);bond (concrete to reinforcement);bonding;concretes; cracking (fracturing);crack width and spacing;prestressed concrete; prestressing steels;pull-out tests;stresses;tensile strength;tests.

DOI: 10.14359/11277

Date: 11/1/1972

Abstract:
The bond-slip relations obtained from six pull-out specimens and six tensile bond specimens are reported. Three covers 0.5, 1.0, and 1.5 in. (1.27, 2.54, and 3.81 cm) were used, the strand being held horizontally during casting. In all cases the bond-slip curve could be identified as elastic-plastic , there being no deterioration in the maximum bond stress with increasing slip unless a longitudinal crack occurred. For the small number of specimens tested, the shape of the curve was found to be independent of the method of testing but the maximum bond stress increased as the cover decreased. The average data obtained was used to predict the average crack width at various stresses in the tensile member, these results are compared with the average crack width obtained during eight tensile member tests. The actual scatter and the predicted scatter of results are also compared. The predictions using the most accurate formula are good, the predictions lose accuracy with the use of simplified formulas but the errors are on the conservative side.