Title:
Improved Formulations for Unbonded Tendon Stress at Ultimate Based on ACI/PTI CODE-320-25
Author(s):
Thomas Kang, Kwanwoo Yi, Jonathan Hirsch, and K. Dirk Bondy
Publication:
Concrete International
Volume:
48
Issue:
7
Appears on pages(s):
69-77
Keywords:
ACI-PTI CODE-320-25, experimental data set analysis, flexural capacity, model derivation, plastic hinge, tendon stress at ultimate (fps), theoretical approach, unbonded post-tensioned concrete.
DOI:
10.14359/51751806
Date:
7/1/2026
Abstract:
This study evaluates tendon stress at the ultimate state (fps) based on ACI/PTI CODE-320-25 provisions. This standard provides discontinuous equations based on the span-to-depth ratio but does not account for span continuity. A new model, based on the plastic hinge concept, addresses this limitation. The model maintains a similar structure to ACI/PTI CODE-320-25 but improves upon its consistency while maintaining accuracy and precision.
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