SEISMIC RESPONSE OF PRESTRESSED CONCRETE BRIDGES

Abstract

Bridges are essential links for transportation lifeline system. They should remain safe during and after devastating earthquakes. Nowadays Prestressed concrete has become a familiar option in bridge works. During past earthquakes many prestressed concrete bridges damaged due to the strong horizontal and vertical ground motions and horizontal prestressed members like girders were failed due to the high moments induced during the seismic event. Omission of dynamic behavoiur in the analysis and poor design were the main reasons behind the damage. The additional Girder fiber stresses which would be produced during earthquake could be controlled by changing the prestressed cable profile design. Approximate change in the cable profile could be determined by studying the response of the structure for seismic load condition. In the present study the influence of various parameters on the dynamic response of the prestressed concrete girders was studied and required change in the cable profile for various parametric conditions was determined. Numerical studies were also conducted to determine an equation for evaluating the required change in the cable profile. With this help of numerical study approximate additional eccentricity, required to resist the additional moments which induced by seismic loads could be determined.