Effects of Traveling Wave Excitation for Super Longspan CableStayed Bridges

Abstract:

The equation of motion under nonuniform excitation of supports was derived in the form under uniform excitation. Through the modal analysis, the modal participation factors and the equivalent modal ground accelerations with consideration of traveling wave excitation were obtained, so that the influence of traveling wave excitation on dynamic responses could also be judged in a response spectrum of this equivalent modal ground acceleration. Vibration mechanism analyses with consideration of traveling wave excitation by mode analysis method were carried out for a trial designed symmetrical cablestayed bridge with a central span of 1 400 m. The deformation of the cablestayed bridge under different support displacements due to traveling wave excitation was analyzed by pseudostatic analysis. Effects of traveling wave excitation on seismic response for super longspan cablestayed bridges with energy dissipating system in longitudinal direction, were researched by the displacement timehistory method. The results show that traveling wave excitation decreases energy dissipating of the piers so that seismic damage of the pylons aggravates. Effects of traveling wave excitation on seismic response for longspan cablestayed bridges with energy dissipating system were disadvantageous, especially under longperiod ground motion with the wave velocity within 1 000~3 000 m?s-1. Therefore, traveling wave excitation should be taken into consideration in seismic response analysis of longspan cablestayed bridges with energy dissipating system.