This study focuses on bridge structural health monitoring by installing on slabs and piers the vibration-based power generation devices, which can generate power by converting environmental vibrations into electric energy by electrostatic induction and can detect slab damage and pier scours by the change in the generated energy. An energy generation index to detect slab damage and a reference-free method to detect uneven pier scour are proposed. To illustrate and verify them, numerical slab models and pier models are constructed, and their modal frequencies and mode shapes are obtained by eigenvalue analyses. Damage-induced change in modal frequency and mode shapes are investigated, in which the analytical details are given in Section 2. The energy generated from the vibrations of the numerical models are calculated and the proposed methods are introduced, with theirverification in Section 3. Finally, several concluding remarks are provided in the last section.