Seismic behavior of steel eccentrically braced frames under soft-soil seismic sequences

The goal of this paper is to examine the seismic response of eccentrically braced frames (EBFs) under artificial narrow-band mainshock-aftershock sequences by means of detailed analytical models representative of buildings designed under the Mexico City Code criteria. These analytical models take into account the nonlinear behavior of the links including a failure criterion. Relevant results for engineering practice showed that strong aftershocks could significantly increase interstory drift demands once the link fails, while surrounding members (adjacent beams, columns) behave nonlinearly, which is opposite to the design philosophy. In addition, it was noted the nonuniform distribution of hysteretic energy along-height of the links, which do not take fully advantage of the energy dissipating capacity of the shear links.