Dynamical　governing　equations　of　a　beam　with　piezoelectric　shunt　damping　were　developed,　and　a　generalized　transfer　function　applicable　for　different　shunt　circuits　was　derived　and　analyzed　comparatively.　The　optimal　shunt　circuit　components　were　also　explicitly　determined.　The　numerical　results　reveal　that　the　LR　parallel　circuit　and　LR　series　circuit　enable　to　effectively　reduce　vibration　amplitude　with　the　identical　effectiveness　in　vibration　suppression.　The　LR-C　parallel　circuit　allows　to　reduce　the　the　required　inductance　due　to　the　supplementary　capacitance　with　less　effectiveness　in　passive　damping.