BEHAVIOUR OF JOINTS WITH FRICTION DAMPERS UNDER COLUMN LOSS SCENARIO

In recent years, several researches have been oriented towards the Low-Damage structures which are able to minimize the earthquake damage by localizing the demand in easily replaceable parts. In this framework, the European research project FREEDAM introduced a particular type of friction dampers for steel structure placed at beam ends of the moment resisting joints. These type of dampers have shown an excellent response under monotonic and cyclic loading, and they have been pre-qualified under seismic loads. The aim of this study is to investigate the performance of these type of joints subjected to a column loss scenario; to this aim a refined numerical model was properly developed and validated against the experimental tests present in literature. The results has highlighted that, when subjected to large rotation, the damage is concentrated in the bolts of the upper T-stub which could leads to a premature collapse of the joint. Therefore, a strengthening solution was properly designed and numerically investigated. The introduced strengthening solution does not interfere with the global joint performance under monotonic and cyclic loads, but allow to enhances the tensile resistance of the upper T-Stub providing a very ductile behaviour.