Abstract
In order to examine the aseismic safety, based upon the incidence of low-cycle fatigue damage in the connections of steel structures, this paper deals with stress-strain behaviors and plastic fatigue strength of welded beam-to-column connections subjected to cyclic bending moments. Cantilever type specimens were subjected to cyclic load ngs at the tips of the beams in a manner of constant tip deflections, until the specimens were fractured at the beam ends. Loads, deflections and the strains at or near the beam ends were measured during cyclic loadings. From the test results, it was observed that local strains at or near the beam ends were distinctly influenced by the geometrical shapes of the beam ends and the thermal hysteresis due to welding at the initial states. However, after the two cycles later, each strain was stabilized and showed the constant value. Low cycle fatigue strength of the actual beam ends was computed using linear relations in a log-log scale between the average non-dimensional strain ranges at the beam ends and the lives at the fracture or the crack initiation lives, and were compared with those of JIS SS 41 base metals and the welded joints. The marked deterioration of the fatigue strength was pointed out for the welded beam-to-column connections.
