A wide set of nonlinear dynamic finite element (FE) simulations is presented and discussed to highlight peculiar behavioral aspects in the seismic response of high-rise mega-braced frame-core buildings. In detail, 45- and 75-storey 2D frames, extracted from 3D case study structures composed of an internal two-way braced core, were designed according to European rules and then analyzed numerically, using inelastic force-based fiber elements to model structural members and mechanical idealizations to reproduce the behavior of bolted beam-to-column joints and welded gusset-plate connections. Out-of-plane imperfections of braces were explicitly included in the simulation to permit potential buckling mechanisms in both braces and gusset plates. Global and local performance of mega-frame systems and key structural components were investigated and the effects of bracing systems and outriggers/belt trusses were quantified. Sensitivity to the structure height was explored comparing the response of the two case study steel moment resisting frame (MRF) structures examined.
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