Local scours around bridge piers can jeopardize stability of the bridges and induce their entire failures. Therefore, there is a great need to assess safety of bridge piers with local piers. With this concern, this study investigates the effects of scours on safety of bridge piers using fluid-structure vibration responses. In particular, numerical simulations are performed to evaluate dynamic stress and displacement fields of bridge piers in different local scours scenarios, by which the mechanism for inducing failures of bridge piers by local scours can be revealed in a statistical manner. Further, real ultimate bearing capacities of bridge piers with local scours can be estimated. By means of inverse analysis, the limit parameters of local scours such as depths and areas can be determined. The results suggest that ultimate bearing capacities of bridge piers decrease with parameters of local scours, and entire failures can occur when the parameters approach their limitations.