a device for positioning in a civil engineering structure at least one fixed point which , in normal time , locks a point of part of the structure in position relative to another , supporting , part which is considered fixed . in order to return the structure part to its initial position as soon as the disturbing action thereon ceases , the device comprises at least two prestressed damping springs which are mounted in opposition either side of the fixed point and act , first , on the structure part which can move in relative manner , such as a bridge floor and , second , on a structure part considered fixed , such as a bridge pier .