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Under extreme seismic conditions, engineering structures experience small numbers of very large displacement cycles. Reinforcing bar steel properties under very large displacement cycle loading can be studied by means of low cycle fatigue (LCF) test. In this study, we developed a low cycle fatigue testing system, which enables to study the low cycle fatigue strength of concrete reinforcing steel bars in the extreme large strain field; under such conditions the number of reversal to failure is well below one hundred cycles. A further advantage of this system is represented by the fact that the specimen is subjected to bending deformation. The obtained extremely low cycle fatigue (ELCF) strength for B450C (FeB44k) steel ribbed bars was compared with the results from smooth bars in order to assess the effect of ribs on the extremely low cycle fatigue behavior; further smooth bars were also subjected to heat treatments different from Tempcore, or surface modified by shot peening or by atmospheric corrosion.
KEYWORDS. Concrete reinforcing bar; B450C (FeB44k) steel; Low cycle fatigue