Seismic behaviour of joints made of high strength steel tubular columns

Nowadays exceptional actions, as fire and earthquake, are fundamental in the design of structures. HSS is usually employed in mechanical applications or in particular fields as offshore structures. In the last years there has been a growing trend in the use of HSS in tubular structures thanks to EN1993-1-12 (2007) that extended its scope to steel grades up to S690Q/S700MC. Nonetheless, EN1993-1-12 (2007) imposes many limitations at level of material, structure and design, probably due to poor knowledge of the actual behaviour. As shown in this work the use of HSS can be advantageous when employing columns in moment resisting frames (MRF) designed according to the capacity design philosophy.