IDA-based seismic fragility of high-rise frame-core tube structure subjected to multi-dimensional long-period ground motions

Due to resonant effects, a lot of high-rise structures could be severely damaged under long-period seismic excitations. In this study, the seismic fragility method based on incremental dynamic analysis (IDA) is employed to quantitatively evaluate the damage levels of high-rise structures under long-period ground motions. Firstly, the frequency contents of special long-period ground motions are analyzed. Then, the finite element models of high-rise frame-core tube structures are established and verified. Lastly, the IDA curve clusters, quantile curves, probabilistic demand models, exceeding probability curve and seismic fragility matrix of the structure under multi-dimensional long-period ground motions are researched respectively. The analytical results show the amplitude contents of long-period ground motions are mainly distributed in the narrow low-frequencies band. Long-period earthquake is more likely to cause structural collapse than ordinary earthquake under large earthquake intensity, and the seismic fragility analysis based on a certain exceeding probability needs to consider the adverse effect of the increased horizontal translational components. The research conclusions will provide urgently needed theoretical basis for seismic design in areas with hidden long-period earthquake damage, and it also promote the development of seismic design methods and the improvement of seismic structural measures for high-rise structures.