GIRDER DESIGN OF A BALANCED CANTILEVER BRIDGE WITH ANALYSIS USING MIDAS CIVIL

Balanced cantilever bridges are used for special requirements like 1) Construction over traffic 2) Short lead time compared to steel 3) Use local labour and materials. If continuous spans are used, the governing bending moment can minimised and hence the individual span length can increase. But unyielding supports are required for continuous construction. Hence for the medium span in the range of about 35 to 60 m, a combination of supported span, cantilever and suspended span can be adopted and bridge with this type of superstructure is known as balanced cantilever bridge. This chapter include the analysis and design of a 50m span prestressed balanced cantilever bridge which comprises of 6 numbers of Pre-Cast Post Tensioned-I Girder 38m long Simply Supported at one end and connected through a Cast-in-Situ Stitch Concrete to a Continuous Balanced Cantilever Box Girder (2x11m). The bridge structure has been modelled by Finite element Technique using MIDAS Civil and analysis has been performed to get various output such as primary and secondary bending moment, shear forces and torsion quantities at various locations of the bridge. The design of super structure is performed as per IRC standards. Keywords— Balanced cantilever bridge, Prestressed, I girder, Box girder, Primary and secondary moments and MIDAS Civil