SOILSTRUCTURE INTERACTION AND CABLE TENSION ADJUSTMENT STUDIES OF A PEDESTRIAN CABLE-STAYED BRIDGE

Abstract

A cable stayed bridge having two towers at the ends of its span is an unusual form. One such cable stayed pedestrian bridge of 72 m. span, which also happens to be the first cable-stayed bridge in India, has been taken up for study in this dissertation, for (a) effects of soil-foundation interaction on the superstructure and (b) the adjustment of tensions in the various cables required for minimising the stresses in the girders. The first part of the study has also been carried out for two more cable sizes in addition to the existing size of the cable. It is seen that insignificant changes occur in the various forces in girders, while reduction in backstay forces is significant when the cable size is reduced from 35mm dia. to 30mm dia. but this reduction does not overstress the cables. Consideration of the soil-structure interaction may yield higher stresses in the girder and tower to a great extent in the case of weak soils, hence essential for the analysis and design of the bridge. Geometric non-linearity effects in the cables have also been incorporated in the analysis; for which a computer program has been developed. Results show that for the accurate and safe analysis of bridge design, non-linear analysis should be carried out.