Abstract
The purpose of this paper is to consider about cyclic hysteretic behaviors of structural steel in unstationary and stationary state subjected to cyclic tension-compression test under a constant strain amplitude after plastic pre-strain and to make a proposition for hysteretic stress-strain relations under random strain amplitudes using the relationship between secant moduli and strain ranges of the stationary hysteretic loops. The test specimens are manifactured by machineworks from reinforcing bars (SR 24, 16mm diameter) and steel plates (SS 41, SM 50, 16mm thickness), Load is applied by a universal testing machine through the gripping devices for tension and compression tests. In regard to the cyclic tests under constant strain amplitudes and the proposed method for prediction of behaviors of steel under random strain amplitudes, the results are summarized as follows; (1) Hysteretic loops under a constant strain amplitude become stationary after several cyclic numbers, In the case of large amplitude, the stationary loops can be moved in parallel along the strain axis according to the pre-strain and in the case of small amplitude (R<4ε_Y), they cannot be moved by the above-mentioned method, but when the upper revarsal point is in the strain-hardening range, they can be moved by the same method. (2) The experimental curves of cyclic stress-strain relations under random strain amplitudes can be followed by the proposed method with good accuracy.
