Feasibility and effectiveness of replacing built-up members with hollow and concrete-filled section for bow-truss bridge

Abstract

This paper investigates the comparative study of the conventional bow truss bridge proposed at Rishikesh, India with the composite bow truss bridge (new construction technique). Firstly, the bridge has been designed by considering the conventional sections of steel. By adopting a modified construction technique, the top chord member of the bridge is replaced with a concrete-filled steel box section; bottom girder, diagonal and cross girder (tension members) with hollow steel box sections. For replacement analysis, the FEM model is validated with the experimental data. The 200x200x8mm steel section (fy=374MPa) filled with concrete (fck=42.5MPa) is found suitable for top chord members. Buckling and plate yielding analysis for the box section are also investigated; due to higher stress concertation only two opposite sides of the plate yield. For obtaining the economic design, the cost comparison has been carried out, which shows that the composite section can cut the overall cost up to 51% when assuming pinned connections and 13% when assuming fixed connections. Furthermore, the effects of the joint (by considering the hinge and fixed) have been analyzed to check the critical connection and end failure of bridge members.