EFFECT OF LATERAL BRACE STIFFNESS OF A LARGE-SPAN STEEL ARCH BRIDGE ON RESPONSE OF THE WHOLE BRIDGE

With the development of the technology of bridges building in our country some new modeling and complex structures of large-span steel arch bridges have appeared. Earthquake happens frequently in china, so it is of significance to ensure safe operation of these bridges under seismic loading. Taking Fenghua Bridge in Tianjin, which is a novel and complex three-dimensional surface steel arch bridge, as the research objects the self-vibration characteristics are studied under Tianjin wave. At the same time the law of internal force and displacements of arch rib are discussed under consistent three-dimensionality excitation and traveling wave effect respectively. Furthermore, the effect of change of lateral brace stiffness on seismic response of the whole bridge is studied under consistent three-dimensionality excitation. Some conclusions which could provide some references for the further theoretical study and design of this new type bridge are obtained. Vaults of large-span steel arch bridges have much less sensitive degree to the internal force than arch foots, while bridges with smaller lateral brace stiffness have more internal force than the bigger ones under the same seismic loading. What is more, lateral brace shows significant influence on transverse moment and bigger lateral brace stiffness is adverse to the transverse moment of arch rib.