Response and fragility of long-span truss structures in ultra-high voltage substation subjected to near-fault pulse-like and far-field ground motions

This study numerically investigates the seismic responses, bearing capacities, and fragilities of long-span truss structures (LSTSs) in ultra-high voltage substations subjected to near-fault pulse-like (NFP) and far-field (FF) earthquakes. The finite element model established in ABAQUS software considers the tower-line dynamic coupling effect, and it is excited by 20 NFP and 20 FF earthquakes. The seismic responses and bearing capacities are analyzed to generate the design recommendations for LSTS. According to five performance levels, the fragility curves are developed by performing a fragility method based on intensity measure. The peak displacement, acceleration amplification factor, bearing capacity, and fragility results significantly indicate that the seismic risk of LSTS under FF earthquakes is much higher than that under NFP earthquakes. Moreover, there are three typical failure modes (i.e., I – III) of LSTS under strong earthquakes. Mode I is a brittle failure while mode III is a ductile failure. Furthermore, the bearing capacity basically obeys a lognormal distribution, and the distributions subjected to NFP and FF ground motions are very close.