An adaptive version of the capacity spectrum method is proposed to estimate deformation demands of steel moment-resisting frames under seismic loads. Its computational attractiveness and capability of providing satisfactory predictions of seismic demands in comparison with those obtained by other advanced nonlinear static procedures in literature are examined. Both effectiveness and accuracy of these approximated methods based on pushover analysis are verified through an extensive comparative study involving both regular and irregular steel moment-resisting frames. The results obtained by nonlinear static procedures and nonlinear dynamic time-history analysis under spectrum-compatible accelerograms are eventually compared. The proposed procedure generally gives a more accurate solution than that obtained from the other nonlinear static procedures.
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INFLUENCE OF THE CYCLIC BEHAVIOUR OF BEAM-TO-COLUMN CONNECTION ON THE SEISMIC RESPONSE OF REGULAR STEEL FRAMES
The work presented is aimed at the investigation of the influence of beam-to-column connection typologies on the seismic response of MR-Frames designed according to the Theory of Plastic Mechanism Control (TPMC). The investigated typologies are four partial strength connections designed in order to obtain the same flexural resistance. The first three joints are partial-strength semi-rigid connections while the fourth one is a beam-to-column connection equipped with friction pads properly designed to assure the earthquake input energy dissipation. Beam-to-column joints are modelled by means of rotational inelastic spring elements located at the ends of the beams whose moment-rotation curve is characterized by a cyclic behaviour accounting for stiffness and strength degradation and pinching phenomenon. The parameters characterizing the joints cyclic hysteretic behaviour have been calibrated on the base of experimental results aiming to the best fitting. The prediction of the structural response has been carried out by means of IDA analyses.