DESIGN AND ASSESSMENT OF STEEL STRUCTURES
IN SEISMIC AREAS: OUTCOMES OF THE LAST ITALIAN
CONFERENCE OF STEEL STRUCTURES
Department of Civil Engineering, University of Salerno, Fisciano (SA), Italy
The use of steel for seismic resistant structures is a hot-topic of seismic engineering. During the last Italian Conference of Steel Structures – CTA 2017, held in Venice, the largest part of the conference proceedings was focused on seismic issues regarding the design and evaluation of seismic performances in new buildings and the use of steel for the retrofit of existing buildings. The use of steel in seismic areas is not new as testified by many patents starting from the first decades of the Italian Kingdom [Cocco, 2018]. In fact, as it is known, steel construction in seismic areas provides many advantages as the weight reduction with a consequent reduction in seismic actions demand. In addition, steel members are usually able to develop wide and stable hysteresis loops under seismic loadings, thus affecting the global ductility of buildings [Mitsui et al., 2018]. For this reason, the need to accurately model the actual cyclic behaviour of steel member by means of simplified model becomes an urgent need. In particular, recent research efforts have been devoted to the modelling of degradation phenomena and pinching effects affecting the ultimate behaviour of dissipative zones and the overall seismic response of the structure [Giordano et al., 2017; Chisari et al., 2017]. In particular, moment resisting frames behavior under seismic loadings can be strongly affected by the degradation phenomena occurring in dissipative zones [Bernuzzi et al., 2018; Montuori et al., 2016a; Dell’Aglio et al., 2017; Ferraioli et al., 2016; Ferraioli et al. 2018a; Ferraioli et al., 2018b]. Moment Resisting Frames are usually cheaper than other steel typologies and assures an adequate seismic dissipation, provided that, connections are appropriately detailed and able to support the required strength and behaving as rigid connections [Tartaglia et al., 2018; D’Aniello et al., 2017; Tenchini et al., 2018; Pecce, 2016]. However, Moment Resisting Frames could not be used for high-rise buildings because of their high deformability for which braced frames or dual systems are preferred [Bosco et al., 2016; Faggiano et al., 2016; Costanzo et al., 2016; Montuori et al. 2016b; Montuori et al. 2016c; Montuori et al. 2017b; Costanzo et al. 2017; Costanzo et al., 2018; Mastrandrea et al., 2013]. In the last years, also cold formed profiles are getting head in the seismic field, used not only as a system for the strengthening and retrofitting of existing buildings [De Matteis et al., 2016; Castaldo et al., 2016; Totter et al., 2018; Formisano et al.; 2016] or for pallet racks [Gabbianelli et al., 2016] but also as the main structural system of new buildings, showing very small interstorey drift [Campiche et al. 2018] or as an innovative bracing system [De Matteis et al., 2018]. Other research fields regard the use of dissipative devices in place of traditional dissipative zones such as beam ends for moment resting frames or link for eccentrically braced frames [Lemos et al. 2018; Latour et al. 2018; Titirla et al., 2017; Fabbrocino et al., 2016]. The use of these devices, properly located in points where the high displacement demand is expected allow the structure to remain in service also after the seismic event and an adequate reparability, benefit the maintenance costs. From the other side, the use of base seismic isolation remains a useful strategy to limit the plastic excursion and, as a consequence, the structural damage [Avossa et al., 2017; Castaldo et al., 2016b]. The finish line is now the design and construction of buildings able not only to assure an adequate level of dissipation and reparability but also the chance to control the residual drift after both the single seismic event and seismic sequences.
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