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.
steel moment-resisting frames
Effect of the new Italian Technical Regulations for Constructions on the seismic resistance of steel frames
The Technical Regulations for Constructions of 2008 (D.M. 14/01/2008) are the final step of the development of the new seismic code which has taken place in Italy in the last five years: the O.P.C.M. 3274 in 2003, the O.P.C.M. 3431 and D.M. 14/09/2005 in 2005 and, finally the D.M. 14/01/2008 in 2008. This code has introduced important innovative seismic design practices for building structures, such as performance based design, use of strength criteria based on limit state method instead of allowable stress method, definition of high and low ductility structures, a new and very articulated framework for the evaluation of the design seismic force, capacity design criteria, etc. In this paper the regulations provided by the new Italian seismic code for steel moment-resisting frames and for concentrically braced frames are analysed and compared with those of the old Italian seismic code (D.M. 16/01/1996). The outcome of the comparison depends on the structural type, however the obtained results show that often lateral strength demand stipulated by the new code is less conservative.
For this paper is available an extended abstract after the text in Italian