Effect Of The Direction Of Ground Motion On Long Span Cable-Stayed Bridges

The propagation direction of natural seismic ground motion is random, and long span cable-stayed bridges are linear-shape structures. Therefore the included angle between the direction of ground motion and longitudinal girder of cable-stayed bridges is also random. At present, the effect of ground motion direction have all been taken into account. However the direction of ground motion usually is longitudinal or lateral or vertical, which may be not control design case. It is possible that there is a certain included angle between ground motion and cable-stayed bridge, which is worst. And the control included angle for each structural member is different from each other.Firstly, some related references are collected and analyzed. The seismic analysis methods and its development are introduced and compared with each other. A long span cable-stayed bridge is regarded as an engineering example. The finite element model of the bridge is established with the software MIDAS/civil. Then the dynamic characteristics are calculated.Based on the natural frequencies and modes, the seismic responses of the bridge are analyzed with different included angles by response spectrum method in frequency domain and time history method in time domain respectively. The effect of seismic ground motion direction on the displacements and internal forces of bridges is investigated.Finally, based on the research, some conclusions are drawn. Some suggestions and problems to be solved urgently in the further are presented.