Hysteretic behavior characterization of friction-damped braced frames

The dissipative capacity of friction-damped bracing systems is evaluated by a statistical characterization of the amplitude and frequency of the slip excursions during a seismic excitation. one-story, friction-damped braced frames are subjected to artificially generated stationary accelerograms, which are compatible with the normalized elastic response spectrum proposed by Eurocode 8. The dynamic response of these frames is analyzed by a step-by-step procedure, which accounts for the variation in the structural parameters, identified by suitably modeling the force-displacement cycle of the dissipative bracing system. Approximate analytical expressions of the aforementioned quantities, characterizing the hysteretic behavior of the frame, are also deduced, These expressions are then utilized to define the range of optimal values of the global slip load leading to a high performance of the devices, The criterion adopted to model the force-displacement cycle of the friction-damped bracing system can be opportunely applied to bracing systems involving different dissipative mechanism's, such that the results obtained can be generalized. Moreover, a criterion of equivalence is proposed, which makes it possible to extend the conclusions of the study to multistory braced frames for which the structural parameters of the equivalent one-story system represent global parameters. Same practical applications pertaining to the case of an actual seismic accelerogram show the validity of the design suggestions proposed.