This study investigates the influence of member geometry and loading history on the deformation capacity of welded I-shaped steel beam members under cyclic loading that permits local buckling. Three ultimate limit states are defined, and deformation capacity curves up to each state are established based on the lower-bound results from constant-amplitude cyclic loading tests. It was confirmed that beam members experiencing large-amplitude cycles inducing local buckling exhibit improved deformation capacity compared to those with lower local buckling damage. This is attributed to strength degradation in the beam and the resulting mitigation of plastic strain accumulation at the welded ends.
