Seismic analysis of partially restrained composite frames coupled with dissipative bracings

The paper investigates the dynamic behaviour of partially restrained steel-concrete composite frames coupled with viscoelastic dissipative bracings. A numerical model which accounts for both the resisting mechanisms of the joint and the viscoelastic contribution of the dissipative bracing is introduced and briefly discussed. The model is first validated against outcomes achieved at University of Ancona, Italy on a one-storey two-bay composite frame subjected to free vibrations. The model is then used to carry out a number of time-history analyses considering various types of earthquake ground motions, different values of peak ground acceleration and different mechanical characteristics of the dissipative device. It is pointed out that the viscoelastic bracing can be used as an effective dissipation system alternative to the plastic hysteresis, with the further benefit of preventing permanent structural damage.