Q–Δ Resonance Analysis in Super-High-Rise Buildings Under Long-Period Ground Motion Using 3D Frame Models

Abstract

Q–Δ resonance is the phenomenon in which the large displacement of a vertical member or structure with different stiffnesses in the two horizontal directions induces a torsional mode response owing to geometric nonlinearity and the related internal resonance. This phenomenon may have a substantial impact on super-high-rise buildings, whose horizontal displacement response can be remarkably large due to long-period ground motion. In this study, the responses of two non-eccentric super-high-rise buildings, which satisfied the Q–Δ resonance conditions, to long-period design ground motions were investigated using 3D frame models. One was a 320-m-tall, center-core, super-high-rise building model with outriggers, and the other was a 200-m-tall, center-core, super-high-rise building model without outriggers, in which the bending deformation became relatively large. Time-history response analysis was conducted considering geometric nonlinearity, and the results suggested that the torsional response induced by the Q–Δ resonance could significantly increase the horizontal acceleration response. The countermeasures against long-period ground motion in super-high-rise buildings should consider the torsional response even in non-eccentric buildings.