Development of revised stiffener spacing requirements for seismic links in eccentrically braced frames

• Κύριος συγγραφέας: Σκρέτας, Νικόλαος
• Άλλοι συγγραφείς: Skretas, Nikolaos
• Γλώσσα: English
• Έκδοση: 2022
• Θέματα: Eccentrically braced frames; Short links; Intermediate links; Seismic effects; Structural steel; Βραχείς σεισμικοί σύνδεσμοι; Ατσάλινες κατασκευές

The current dissertation re-examines the transverse stiffener spacing requirements of short andintermediatelengthseismicsteellinksineccentricallybracedframes(EBFs).Transverse web stiffeners enhance the rotation capacity and the link’s ability to dissipate energy due to seismic excitation. The current seismic design standards require the use of transverse stiffeners for EBF links of short and intermediate length. The maximum permitted distances in order to achieve the desired seismic performance targets are established in current seismic provisions. These design procedures for EBFs have been based on semi-analytical and experimental studies on isolated links that were carried out in the ’80s. In the current study revised stiffener spacing requirements for short and intermediate length links in EBFs in order to attain the maximum permitted inelastic rotation capacities per EN1998-1 are proposed. At first, an experimental dataset was assembled and presented. This dataset was compiled with a particular focus on the stiffener spacing requirements and conclusions regarding the link’s inelastic rotation capacity and overstrength were extracted. Furthermore, it was substantiated that the stiffener spacing requirements established in EN1998-1 are overly conservative. Theproposedstiffener spacing limits are established on the basis of a methodology that combines a numerical solution of the classical problem of inelastic plate buckling. Hence, the analytical problem of the inelastic plate buckling is presented as well as the used numerical procedure for solving it and the derivation of the proposed stiffener spacing limits for short and intermediate length links. The resultant design equations are then verified through finite element simulations. The finite element modeling approach has also been presented and the reliability of the finite element simulation results has been investigated. Finally, it is concluded that the stiffener spacing rule per EN1998-1 for intermediate length links may be unconservative for some link geometries and that the proposed design rules may be a possible replacement of the current rules for short and intermediate length links.