Seismic redesign of steel frames by local insertion of dissipating devices

摘要

The possibility of extending to steel moment resisting frames a retrofitting technique, previously developed for RC structures, is investigated in this work. This technique is based on the incorporation of energy dissipating devices around the regions where inelastic behaviour due to a strong earthquake is expected. This extension, however, is not straightforward, due to the deeply different nonlinear behaviour of steel and RC members under cyclic flexure. Therefore, in a first step, a numerically efficient analytical beam model has been developed, to represent the nonlinear behaviour of the devices, and has been implemented in the computer code STEFAN for the nonlinear analysis of steel plane frames, which adopts realistic models for both beam elements and joint panel zones. Secondly, making use of the code STEFAN, an 8-story, 5-bay frame, designed according to Eurocodes 3 and 8 prescriptions, has been analysed, both in its original and redesigned state. The results of the nonlinear analyses confirm the positive effects of dissipating devices for the case at study.