Seismic assessment of steel frame subjected to simulated directivity earthquakes: The unilaterality of fault normal component at various rupture distances

Directionality is prominent in the fault normal component of ground motion. It has a different effect on stations in the rupture direction on the tectonic fault than it does on stations in the opposite direction. Such pulse-like features observed in forward and backward directivity stations affect both low-rise and high-rise structures, depending on their fundamental period and the pulse period of ground motion. However, systematic availability of both forward and backward directivity ground motion for unilateral and bilateral earthquakes of the same magnitude at a similar rupture distance for a given fault is rare. So, multiple directivity scenarios are simulated using fracture mechanics-based principles. Using OpenSees, steel moment-resisting frames of 1, 5, and 9 stories, well designed according to building codes, are modeled, and their non-linear response is evaluated. Stations at constant rupture distances are used to compute fragility for each scenario separately. Variation inter-storey drift and peak floor acceleration, along with the hysteretic behavior of panel-zone springs, have also been studied for each of the directivity scenarios. Finally, the results obtained are compared to what is expected by HAZUS. © 2021 Elsevier Lt