Webinar: High Strength PT Bar Revisited, Reminders, and Recommendations-Webinar: High Strength PT Bar Revisited, Reminders, and Recommendations

Video Transcription

Video Summary

The Post-Tensioning Institute's September webinar, moderated by Kyle Boyd, focused on high-strength PT bars, commonly used for rock and soil anchors and concrete structures. The webinar, part of a monthly series, featured experts Pete Spire, Vice Chair of the Pre-Stress Rock and Soil Committee, and Andy Baxter, a professional geologist and engineer.<br /><br />The session covered the distinctions and applications of A722 bars and the implications of using non-A722 bars like A615 rebar and hollow core bars. Emphasis was placed on the A722's lack of explicit relaxation requirements, addressing the need for updates to ASTM A722 standards based on recent research and advancements in relaxation testing.<br /><br />Three major concerns were highlighted: stress-strain behavior under tensile load, elastic modulus, and relaxation and creep behavior. Detailed comparisons and recommendations were provided for managing relaxation losses, especially in relaxation-sensitive applications such as dam tie-downs and temporary soldier pile walls. Engineers are advised to obtain specific bar relaxation properties from manufacturers, specify relaxation thresholds, and possibly implement monitoring and retention programs.<br /><br />Upcoming webinars will cover topics including post-tension bridges and slab-on-ground design. The session concluded with Q&A, addressing future specifications for relaxation requirements and maximum jacking stress standards for A722 bars.

Keywords

Post-Tensioning

Dual-Banded Layout

Kyle Boyd

Asif Baxi

Tim Crissel

Jonathan Hirsch

Karen Roberts-Wolham

Analytical Modeling

Experimental Testing

ACI PTI Code

Post-Tensioning Institute

high-strength PT bars

A722 bars

rock and soil anchors

concrete structures

relaxation testing

stress-strain behavior

elastic modulus

relaxation and creep behavior