ABSTRACT
The elastoplastic damper devices are frequently used to control the seismic response of structures and, in particular, of continuous bridges. Unlike other anti-seismic devices, the elastoplastic dampers are seismic restraints with hysteretic elastoplastic response capable of controlling the horizontal force level and of dissipating energy due to the earthquake. Sometimes such devices are coupled to temporary constraint devices, which are hydraulic type (shock-transmitters) generally. In case of seismic action, the hydraulic device is able to transmit the forces to the elastoplastic damper, while in case of service load, it does not offer resistance and allows the movements. Due to their performance characteristics, the elastoplastic dampers coupled to shock-transmitters have been used to control the seismic response of the longest Italian bridge, located on A12 highway in Tuscany Region. The paper shows the details of the maintenance project of the devices of the bridge, with a focus on the causes of any and all damage which have been detected during the surveillance.
