Study on the spatial effects of seismic motion on ultra-long integrated transportation hubs

The seismic responses of large-space, long-span, and ultra-long structures exhibit significant differences based on their spatial effects; therefore, it is necessary to conduct an analysis of the seismic responses of various specific structures. To synthesize artificial three-dimensional (3-D) seismic waves based on the 3-D coherence function matrix and traditional trigonometric series method, lower-upper decomposition was used to achieve 3-D coherence matrix decomposition, and the Fourier amplitude spectra method was used to adjust the acceleration time-history. Moreover, the acceleration initialization method and trend elimination using least squares were used to achieve baseline correction. Based on the unidirectional, bidirectional, and triaxial consistent and inconsistent excitation modes, four natural waves and two artificial waves were used for the aseismic calculations of an actual ultra-long structure. The results showed that the excitation dimension had little impact on the inter-story drift ratios, and the traveling-wave effect did not have a serious negative impact on the rotation-displacement ratios. However, the cases of short-side and low-apparent-wave-velocity excitations were unfavorable for the control of story drift and shear force, and the coherent effect significantly increased the peak internal force of the components. There was a greater effect under short-side excitation and a high apparent wave velocity, whereas at a low apparent wave velocity, the traveling-wave effect was strengthened, and component internal forces exhibited polarization. The combined traveling-wave and coherent effects were unfavorable for structural safety. The excitation dimension had little impact on peak internal force and the number of overloaded components under incoherent excitation but a significant impact under coherent excitation, especially triaxial coherent excitation.