Shaking table test on seismic resonant behavior of core‐outrigger structure

In order to investigate disastrous seismic resonant effect of resonant ground motions on tall building structures, a 1/40 scaled planar test model of a 56‐story core‐outrigger structure was tested on shaking table considering two types of ground motions, that is, non‐resonant and resonant ground motions. The non‐resonant ground motions were chosen from far‐field natural earthquake records, whereas the resonant ground motions were generated through scaling Fourier spectra of the non‐resonant ones in a target period region covering one of the first two natural periods of the test model. The test results showed that (a) with the same small peak ground acceleration of 0.07 g, the test model exhibited significant hysteretic behavior, residual displacement, and even overturning collapse under the resonant ground motions but behaved elastically under the non‐resonant ones; (b) the first‐period resonant ground motion caused extremely large displacements on the upper floors and large moments on the lower stories, whereas the second‐period resonant ground motion resulted in extremely large accelerations on the upper and middle floors; (c) the first‐period resonant ground motion was more probable to trigger overturning collapse of the core‐outrigger system after some exterior columns had reached their axial compression strength, even for those columns on the middle stories.