Fragility framework for corroded steel moment-resisting frame buildings subjected to mainshock-aftershock sequences

This study proposes a framework for the seismic fragility assessment of steel moment-resisting frames exposed to different rates of corrosion and subjected to real mainshock-aftershock (MS-AS) sequences. The inherent un-certainties in the structural characteristics may significantly affect the structural performance. Thus, in addition to the demand parameters, the framework considers randomness in the capacity parameters using the Latin hypercube sampling. Three frames are modeled in OpenSees and then subjected to nine real as-recorded MS-AS sequences to illustrate the application of the framework. Four limit states are defined based on the maximum interstory drift ratio and the multiple stripe analysis is chosen for the fragility assessment. The presented framework allows for the plot of the fragility surfaces for each corrosion level conditioned on both the mainshock and the aftershock intensity. The results indicate that corrosion and aftershock may significantly affect the seismic fragility especially for the extreme limit states.

Automated summary

This study proposes a framework for assessing the seismic fragility of steel moment-resisting frames under different corrosion rates and subjected to real mainshock-aftershock sequences. Uncertainties in structural characteristics can significantly impact structural performance. By considering both demand and capacity parameters, the framework incorporates randomness using Latin hypercube sampling. Application of the framework on three modeled frames exposed to nine recorded mainshock-aftershock sequences illustrates its usefulness. The results highlight the significant impact of corrosion and aftershocks on seismic fragility, particularly for extreme limit states.