Fatigue of Welded Steel Structures due to Strong Earthquakes : Strain Controlled Low-Cycle Fatigue Tests of Cylindrical Specimens

Abstract

This experiment was carried out in order to examine cyclic inelastic actions and low-cycle fatigue properties of butt welded joints of steel structures. Base metals which consisted of mild to high tensile strength steel, namely, SS41 to HT80, were used. The weldedjoints were made by means of various kinds of butt welding processes. These base metals and the welded joints were fabricated and shaped into cylindrical specimens, and loaded cyclically by an uniaxial tension-compression method, to the point where the specimens were fractured. No significant differences between the base metal and the welded joint were observed with respect to the cyclic stress-strain relationships and the energy absorption capacities at the steady-state in non-dimensional forms. However, as for fatigue strength, some deterioration was observed at the lower cycles with regard to the welded joints of the base metals whose monotonic tensile strength is relatively high. New quantitative estimations with respect to energy absorption capacity and low-cycle fatigue strength deterioration are also proposed herein.