In reinforced timber beams, the moment of brittle failure, i.e. the transition from the unfractured to the fractured state, is characterized by dynamic effects. In the unfractured state, the stresses under consideration are transferred proportionally by the timber beam and the reinforcement. Brittle failure in the timber results in associated stress release in the beam. The reinforcement is activated to carry the released stresses by deformations between the beam and the reinforcement. This sudden process leads to dynamic impact, resulting in additional stresses in the system. To receive an idea about the corresponding effects, a simple model is presented.