ABSTRACT
Steel s tructures are m o r e a n d m o r e extensively used i n regions of h i g h seismic r i sk , because of their excellent per formance i n terms of s t rength a n d d u c t i l i t y . I t is m a i n l y the mechanical b e h a v i o u r of mater ia ls a n d s t r u c t u r a l elements w h i c h determines the f u l f i l m e n t of the des ign requi rements set b y seismic codes. Diss ipat ive structures are des igned b y a l l o w i n g the y i e l d i n g of some zones of its members , the so-called d iss ipat ive zones. D u r i n g a catastrophic earthquake these zones m u s t dissipate the earthquake i n p u t energy b y means of hysteretic d u c t i l e b e h a v i o u r i n the plastic range. The f o r m a t i o n of a p p r o p r i a t e d iss ipat ive mechanisms is re lated to the s t r u c t u r a l t y p o l o g y . M o m e n t - r e s i s t i n g f rames have a large n u m b e r of diss ipat ive zones, located near the b e a m - t o - c o l u m n connections, w h i c h dissipate energy b y means of cyclic b e n d i n g b e h a v i o u r . Therefore, the d u c t i l i t y of seismic-resistant steel f rames is also deeply i n f l u e n c e d b y the b e h a v i o u r of the ir connections.
