Abstract
In order to clarify the mechanical properties and the low-cycle fatigue strength of the idealized beam-to-column welded joints, this experimental investigation was carried out. Specimens, consisted of JIS SS 41 mild steel plates, were welded by means of CO_2-Gas butt welding or Non-Gas butt welding and fabricated to flat plate shapes which were named A-Type, or crossed shapes named B or C-Type. Three types of specimens were loaded at constant amplitudes from ±0.5% to ±1.5% as the deformations between the gauge length in a manner of quasi-static state. Only the C-Type specimens were subjected to constant bi-axial forces which simulated cyclic bending moments and column axial forces, using a special loading apparatus. The following phenomena were clearly observed from the results of the monotonic tension tests; anisotropy of the mild steel plates in the thickness direction existed and the sensitivity on Lamellar Tearing was quite high. The low-cycle fatigue strength of the A and B-Type specimens is well expressed by the well known Manson-Coffin formulae in terms of the non-dimensional elastic and plastic strain amplitudes and the equivalent fatigue lives. No deteriorations can be remarkable observed from the biaxial fatigue tests using the C-Type specimens in the nondimensional form of fatigue strength, which employed the plastic anisotropy proposed by Hill's yield criteria.
