Title: Unbonded Tendons in Post-Tensioned Concrete Beams Under Repeated Loading

Author(s): H. W. Chung

Publication: Journal Proceedings

Volume: 70

Issue: 12

Appears on pages(s): 814-818

Keywords: beams (supports); crack width and spacing; cyc-lic loads; deflection; fatigue (materials); prestressed con-crete; research; serviceability; unbonded prestressing.

DOI: 10.14359/7140

Date: 12/1/1973

Abstract:
An experimental investigation was undertaken to study the response of unbonded prestressed concrete beams to repeated loading and the effects of repeated loading on the subsequent behavior of the beams. The variables were the amount of prestressing steel and the maximum level of the repeated load. The test results indicate that the cracking and ultimate strengths are not significantly affected by the repeated load provided that the beam does not fail in fatigue, but the deflection and crack widths increase sub-stantially under repeated loading. It is recommended that in design some 25 percent extra deflection be allowed for and the limit state of crack widths be avoided.