Strain-ageing effects on the residual low-cycle fatigue life of low-carbon steel reinforcement

Low-cycle fatigue (LCF) failures can be expected when rebars are subjected to a small number of cycles at large stress/strain amplitudes. Major seismic events are often preceded or followed by other events of smaller/larger magnitude. During each event, the residual fatigue life of the steel reinfor...

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Bibliographic Details
Published in:Materials and structures 2022-03, Vol.55 (2), Article 35
Main Authors: Loporcaro, Giuseppe, Cuevas, Alberto, Pampanin, Stefano, Kral, Milo V.
Format: Article
Language:English
Subjects:
Aging
Aging (metallurgy)
Amplitudes
Bars
Benchmarks
Building construction
Building Materials
Civil Engineering
Cumulative damage
Earthquake damage
Earthquakes
Engineering
Fatigue failure
Fatigue life
Low carbon steels
Low cycle fatigue
Machines
Manufacturing
Materials Science
Metal fatigue
Original Article
Precipitation hardening
Processes
Rebar
Reduction
Reinforcing steels
Seismic activity
Solid Mechanics
Theoretical and Applied Mechanics
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Summary:Low-cycle fatigue (LCF) failures can be expected when rebars are subjected to a small number of cycles at large stress/strain amplitudes. Major seismic events are often preceded or followed by other events of smaller/larger magnitude. During each event, the residual fatigue life of the steel reinforcement may reduce, eventually leading to failure of the bars due to the cumulative damage. Strain ageing may reduce even more the residual fatigue life of steel. This paper presents the results of an experimental testing campaign conducted on samples fabricated from New Zealand Grade 300E steel. A benchmark LCF life was obtained for 12-mm steel reinforcing bars subjected to axial-strain-controlled completely reversed cyclic tests at amplitudes ranging between 0.78 and 2.75%. The reduction in fatigue life attributed to strain ageing was obtained by comparing the benchmark fatigue life with that of steel reinforcing bars precycled up to 33% and 66% of the benchmark life and artificially strain aged for an equivalent period of 1 year at 15 °C. The Coffin-Manson and Koh-Stephens models were employed to evaluate the experimental results. The study demonstrates that, depending on the strain amplitude, strain ageing can cause a reduction in total and residual fatigue life ranging from 20 to 70%. Strain ageing should not be ignored during the assessment of earthquake-damaged steel reinforcing bars.
ISSN:1359-5997
1871-6873
DOI:10.1617/s11527-022-01885-0