THREE-DIMENSIONAL FRAME ANALYSIS OF Q-? RESONANCE OF CENTER-CORE BIAXIALLY SYMMETRICAL HIGH-RISE BUILDING UNDER LONG-PERIOD EARTHQUAKE MOTION

When large displacements occur in buildings with different stiffnesses in the two horizontal directions, torsional moments are generated owing to geometric nonlinearities. Consequently, when the sum or difference of the translational mode natural frequencies in the two horizontal directions is close to the torsional mode natural frequency, the torsional mode is excited. This is known as Q-? resonance. Therefore, we created a three-dimensional frame model of a center-core high-rise building with a biaxially symmetrical plane that satisfied the Q-? resonance condition and examined whether the torsional response was excited by long-period design waves. A time-history response analysis was conducted assuming elastic response and considering geometric nonlinearities. It was confirmed that the torsional mode could be induced.