Seismic upgrading of typical Italian existing RC frames by BRBs

Although many regions of the world are recognized as earthquake prone areas, a large part of the buildings spread on those territories suffer from structural deficiencies and are not able to sustain horizontal forces. For instance, many structures, which are in use today in Italy, are not adequate to face strong ground motions due to different reasons. A large part of the buildings was designed before seismic provisions became mandatory, taking into account the only effect of gravity loads. Many other structures were designed for seismic levels that today are not sufficient, because of the update of the national seismic hazard map. Furthermore, the use of material with lower characteristics than those assumed in the design and their degradation during time yield to even worse seismic performance. The insertion of BRBs in the RC structure is considered a promising solution for the seismic upgrading of RC buildings, and to this end a design method has been presented in a companion paper. This paper aims at testing the developed design procedure on three case study frames, affected by the most common structural deficiencies of Italian buildings. The design method is applied considering different values of the design parameters, to investigate their influence on the response of each upgraded frame. The seismic performance of the rehabilitated frames is assessed by nonlinear dynamic analysis. The results show the effectiveness of the design method, which successfully designs the BRBs for every frame considered, regardless of the specific structural issues. Moreover, information about the most proper values to assign to the ruling parameters is provided.