Abstract: The deformation pattern of the large-span latticed arch under the bi-directional earthquake excitation was predefined and expressed as the linear combination of displacements of the dominant vibration modes. Based on the load pattern derived from the deformation pattern, a nonlinear pushover analysis was carried out to establish an equivalent single degree of freedom (ESDF) system. Then, the responses of the ESDF system were solved by response history analysis method. Finally, the target point of the structure was found so that the seismic responses of the overall structure were obtained accordingly. Since the two components of ground motion inputs were transformed, a simplified procedure for seismic response analysis of the large-span latticed arch under bi-directional earthquake excitations was proposed. The seismic responses of a latticed arch model under a series of bi-directional earthquake waves in firm and soft sites were obtained by the simplified procedure. Compared with the results given by response history analysis, the nodal displacements and the extreme stress of elements are consistent in trends and distributions, with relative errors about 15.1%, 12.5% and 16.6% respectively, and 25% computing consumption.

Key words: latticed arch, seismic assessment, pushover analysis, bi-directional earthquake, deformation pattern