Displacement restrainers, which are usually set asides isolation rubber bearings to restraint transverse displacement of superstructure for damage protection of expansion joints during earthquake, can be utilized as a trigger device to differ vibration modes before/after their breaks. Then, the authors have been developing displacement restrainers with knocking-off function, called as CSB, to mitigate damage of bridge pier and/or its foundation against a strong earthquake. That is, after the CSBs break, a system vibration is expected to shift into isolated one when the breaking load controlled with high accuracy. In this study, the breaking characteristics of the CSBs are experimentally investigated through static breaking tests and the installation effects of the CSBs asides the rubber bearings are also verified through shaking table tests. Moreover the installation effects of the CSBs in a viaduct are revealed through dynamic response analysis. © 2012 Taylor & Francis Group.