In this paper, the effect of material elasticity was evaluated through a simple model as proposed by Wang and Yu (1991), for yield mechanisms of a cantilever beam under tip pulse loading. The beam was assumed rigid-perfectly plastic but instead of the usual fully clamped constraints at its root, an elastic-perfectly plastic rotational spring was introduced there so the system had a certain capacity to absorb elastic energy. Compared with a rigid-perfectly plastic beam without a spring root, the present beam-spring model showed differences in the initial plastic hinge position and the minimum magnitude of the dynamic force needed to produce a plastic failure. It was also shown that various failure responses may happen while the hinge travels along the beam segment towards the root, rather than a unique response mode as in a rigid perfectly plastic analysis.