STRUCTURAL BEHAVIOUR OF CABLE STAYED BRIDGE SYSTEM USING VARIOUS TYPE OF DECK-PROFILES

Abstract

The prime objective of the present work is to study the structural behaviour of cable stayed bridge with different types of deck profiles by by modelling and analysing them under static and dynamic loadings, ensuring that the same span to depth ratio is maintained in all cases. A comparison of their behaviour under static and dynamic analyses was made. The complete work consists of conducting a static and dynamic analysis using commercial software (MIDAS civil) by modelling a 4 lane cable stayed road bridge with main span of 150m and having side spans of 75m on either side supported on two pylons. The deck width at the road surface is considered 23.5m. Single axial layer of stay cables, with 6 nos. on either side of pylon, totalling to 24 nos. are anchored in the median of the road bridge. The total focus has been given to study the performance of the Cable Stayed Bridge with commonly used deck profiles, i.e., PSC- contiguous I girder , PSC-contiguous T beam, PSC-Box girders with single and multi-cells. Parametric study will be to work out the axial and bending stresses in deck and stay cables, displacements and deflections under static analysis. Dynamic analysis is conducted to study the seismic response of cable stayed bridge by using Linear Time History Analysis (THA). Parameters like axial and bending stresses, stresses in stay cables and displacements in the deck, base shears were studied. The study also considers providing a Triple friction pendulum isolator (TFPI) damper at lower girder position of abutments in the bridge for improving dynamic behaviour of bridge. The displacements at the abutments with and without TFPI for all the four deck profiles were studied and compared. Further, a comparison of time periods of the bridges with and without TFPI damper for all the four deck profiles were also made. The results of the study enable engineers in selecting the better performing deck profiles for cable stayed road bridges designed using IRC guidelines for static and dynamic loadings.