SEISMIC DAMAGE ASSESSMENT OF MOMENT RESISTING STEEL FRAMES WITH LOW CYCLE FATIGUE THEORY

The damage assessment in structures that have suffered one or more earthquakes is of paramount importance to predict its post-earthquake behaviour. The actual version of the European seismic design code does not give practical indications about the estimation of damage in connections and members, proposing only a general methodology based on direct in-situ visual inspections. The paper proposes a seismic design strategy to appraise the structure residual life, by combining non-linear time-history (NLTH) analyses with low-cyclic fatigue design approach (LFC). Applications are proposed for a planar steel moment-resisting (MR) frame with semi-rigid connections. The discussed research outcomes show how the damage, which is currently neglected during the design phase, should result a very useful parameter allowing for a direct appraisal of the effective frame performance after one or more earthquakes as well as for the identifications of components needing urgent repairs.