Effect of Pylon Shape on seismic response of Cable stayed bridge with soil structure interaction

Cable stayed bridge are the most flexible bridge and getting popularity because of its economy for longer spans and aesthetics. Here focus is given on the effect of shape of pylon on the seismic response of cable stayed bridge, for this, the bridge span dimension and other parameters are kept constant, and only the pylon shape is varied viz. A type, H type, portal frame, spread pylon and pyramid shapes. The height of the pylon is kept constant for all the shapes for comparison purpose. Here soil structure interaction effects are considered through the soil-spring at the base. The 3D bridge model is prepared on SAP 2000 software and bridge is analyzed seismically by Bhuj 2001, Earthquake India. The bridge response in terms of pylon displacement, acceleration and base moment is obtained. The study reveals that the shape of the pylon has great influence in the seismic response of cable stayed bridge. spread pylon shape are better for resisting earthquake in longitudinal direction but weak in lateral direction, but pyramid shape pylon is better because of its geometry in resisting earthquake force from any direction and also SSI effects are minimum in this case. SSI effects are predominant for soft soil conditions for all pylon shapes.