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Title: Behavior of Reinforcing Bar-to-Concrete Bond under High Sustained Load

Author(s): Ali Elawadi, Sarah L. Orton, and Ying Tian

Publication: Structural Journal

Volume: 120

Issue: 2

Appears on pages(s): 233-245

Keywords: bond length; bond-slip; concrete cover; creep; deflection; reinforced concrete (RC); sustained load; time-dependent

DOI: 10.14359/51737239

Date: 3/1/2023

This study seeks to identify bond strength and bond-slip behavior of deformed reinforcing bars under high sustained loads. ASTM A944 beam-end test specimens were subjected to sustained load levels ranging from 71 to 100% of their ultimate capacity. The sustained loading tests were conducted until bond failure or at least 20 days. Three of the specimens failed under sustained load at load levels as low as 80% of the control specimens. Subsequent loading of the specimens that survived the high sustained load showed that the residual ultimate capacity was not reduced by the application of sustained load. The slip creep under sustained load was on average 124% of the initial slip, and over 45% of the slip creep occurred in the first day. The effects of concrete cover depth and bond length were examined. With the available data, a simple time-dependent model for determining the bond-slip under high sustained loading was suggested.