In addition to seismic isolation, seismic improvement/adjustment of existing buildings is often achieved through the use of dissipators, usually inserted into framed structures as components of dissipative bracings, that is, by using inter-storey displacement to dissipate energy.
The insertion of dissipators in a structure greatly reduces the need for ductility in the structural elements, and therefore greatly improves the ability of the structure to withstand an earthquake.
However, it is not always possible to keep the structure completely elastic, and thus wholly avoid damage to it.
However, a high level of safety can always be achieved, with excellent cost-benefit ratios. It should also be noted that, unlike seismic isolation which is not always feasible in an existing building, the insertion of energy dissipators into an existing framed building is almost always possible, although architectural implications have thus far limited its use mostly to public buildings, especially schools.
Energy dissipators are divided into two families:
Anti-seismic devices used in the seismic upgrading of existing buildings, also include dynamic restraint devices (or ROD type temporary restraint or shock transmitters), devices that constitute a rigid axial restraint between the structures to which they are connected when subjected to dynamic actions (such as an earthquake), but that allow movement in the event of slow actions (thermal expansion).
Typically, these devices are used where the joints between adjacent buildings are not sufficient to connect the different bodies during seismic activity, after checking the overall behaviour of buildings that during seismic activity form a new single seismic resistant structural body.