Seismic Analysis of the Superlong Base‐Isolated Structure Under Multidimensional and Multisupport Excitations

This study utilizes synthetic ground motions to analyze the seismic response of superlong base‐isolated structures, with a focus on their multidimensional, spatially varying, and nonstationary characteristics under actual earthquake conditions. A classic power spectrum model combined with a trigonometric series method is adopted to generate spatially correlated, multisupport, and multidimensional nonstationary ground motions. These synthetic motions were applied to the seismic response analysis of a typical superlong base‐isolated structure: Grand Canal Museum of Beijing. Three excitation scenarios were systematically compared: uniform excitation (UE), excitation considering only the traveling‐wave effect (TWE), and multidimensional and multisupport excitation. Results demonstrate that the maximum displacements, internal forces of isolation bearings and torsional angle of floors under multidimensional and multisupport excitation exhibit significant deviations from those under UE and traveling‐wave‐only excitation. This study confirms that multidimensional and multisupport excitation more accurately captures the seismic response characteristics of superlong base‐isolated structures, thereby providing critical insights for designing and analyzing similar structures in high‐intensity seismic zones.