A design procedure of dissipative braces for seismic upgrading structures

"Existing reinforced concrete frame buildings with non-ductile detailing could suffer severe damage and caused loss of life during earthquakes. In recent years many research activities have been paid to develop innovative and more reliable structural control devices and different rehabilitation systems have been studied to upgrade the seismic performance of this kind of structures. The research discussed in this paper deals with the seismic protection of frame structures by means of passive energy dissipation. A displacement-based procedure to design dissipative bracing for the seismic protection of frame structures is proposed and some applications are discussed. The procedure, based on the displacement based design and using the capacity spectrum method, aims to be used as a professional tool as it does not require sophisticated dynamic nonlinear analyses but only common non linear static analyses. Two performance objective have been considered developing the procedure: to protect the structure against structural damage or collapse and avoid non-structural damage, this is done limiting global displacements and interstorey drifts. In the paper the argument is discussed and compared to other different existing approaches. After the presentation the procedure is applied to case studies. The applications are: two 2D r.c. frames, one infilled and one bare, and finally a real application on an existing 3D."