ASSESSMENT OF THE RESIDUAL CAPACITY OF MR STEEL FRAMES VIA INCREMENTAL DYNAMIC ANALYSIS

Performance and post-earthquake residual load carrying capacity of steel frames can be efficiently evaluated via the Incremental Dynamic Analysis (IDA) approach. Generally, reference is made only to the maximum transient inter-story drift for the damage assessment, but a more detailed evaluation can be also based on damage intensity measure (DM), which appears as a very promising technique to be adopted in routine design. The present paper is focused on existing Moment-Resisting (MR) steel frames, whose post-earthquake performance can be efficiently evaluated with reference to the additional DMs such as residual interstory drift, residual load carrying capacity and low-cycle fatigue damage. The discussed numerical applications are related to 4 planar frames differing for joints and members. Each DM has been appraised at the specific seismic intensity corresponding to design performance levels associated with immediate occupancy, life safety and pre-collapse. Research outcomes underline how the additional information obtained from the proposed DMs contributes to provide a more accurate prediction of the effective damage of the frames, with respect to the one based on the sole maximum transient inter-story drift.