Retrofitting precast frame structures under earthquake load by monolateral dissipative braces

Seismic retrofitting of existing precast concrete frame structures built according to null or inadequate seismic design provisions is a main challenge for the Engineering Community. The typical large spans and heights of these buildings do not allow for the installation of current bilateral dissipative braces, including buckling-restrained braces, due to the unviable brace length required. To this aim, an innovative seismic retrofitting technique based on mono-lateral dissipative bracing is employed. These devices, introduced in the recent years in fields of Engineering other than Earthquake, dissipate energy through friction or plasticisation in tension, while freely deforming in compression. This technique is studied for the seismic retrofitting of a typical precast concrete industrial frame structure representative of the European heritage, among others. Non-linear dynamic time history analysis is employed in this work for the evaluation of the seismic performance of the original building structure and the one retrofitted with highly nonlinear monoliteral braces with different threshold activation loads. The results show the potential benefits of this promising retrofitting technique in providing a complete protection from the earthquake preventing the structure from attaining yield and damage even when subjected to strong motions.