Seismic response of a steel trussed arch structure to spatially varying earthquake ground motions including site effect

This paper investigates seismic response of a realistic large dimension steel trussed arch structure subjected to the combined spatially varying horizontal and vertical ground motions. The ground motion spatial variations associated with wave passage effect, coherency loss effect and local site effect are considered. In numerical calculations, the simulated spatially varying ground motions are individually compatible with response spectrum defined in Chinese Seismic Design Code, and are compatible with an empirical coherency loss function between each other. Compared with structural responses calculated using uniform and delayed excitations, numerical results show that seismic response is amplified when spatially varying ground motions including local site effect are considered. Each factor of ground motion spatial variations has a significant effect on the dynamic response of the structure. Numerical results also indicate that considering simultaneous vertical and horizontal ground motions will lead to more accurate response predictions of the trussed arch as compared with those obtained by considering horizontal excitations only. Therefore, to have an accurate structural response assessment and a better design of long span steel trussed arch structures, a reliable ground motion spatial variation model is essential