A review of initial end slip as criteria of acceptable strand bond quality and the relationship between strand diameter and transfer length for prestressed concrete members.

摘要

ACI 318-05 section 12.9.1 defines a minimum development length for which a prestressing strand shall be bonded. This is "intended to provide bond integrity for the strength of the member." ACI 318-05 equation 12-4 was adopted in 1963 and was based on empirical results of physical tests. In the past 40 years there have been many advances in pretension strand materials and yet equation 12-4 has not changed other than minor clerical modifications. There have been several studies to predict transfer and flexural bond lengths in prestressed concrete that determined that equation 12-4 is limited and in some cases underestimates these transfer and development lengths.;This thesis is three-part: determine through a literature review of previous studies the applicability of end slip as a criteria of acceptable bond and the validity of equation 12-4, categorize techniques used to determine bond quality, and study the effects of strand diameter and effective prestress on the transfer length through a finite element analysis of a simplified model.