A series of modal response spectrum analyses were performed on 60m to 150m spanned lattice domes with the half subtended angle ranging from 20 deg. to 30 deg. to investigate the effect of the dynamic characteristics of the substructure’s higher mode. It was found that the current equivalent static seismic loads underestimate the roof response when supported by multi-story substructure with the 1st natural period in the range of 0.5s to 1.2s. Therefore, a modified equivalent static seismic load considering the antisymmetric roof mode’s amplification by the substructure’s second mode was proposed and validated.
