Feasibility and effectiveness of replacing bow truss bridge members with concrete-filled sections

Abstract

A comparative study of a conventional bow truss bridge, proposed in Rishikesh, India with a composite bow truss bridge (new construction technique) was conducted. First, the bridge was designed by considering conventional steel sections. Then, adopting a modified construction technique, the top chord members of the bridge were replaced with concrete-filled steel box sections and the bottom girders, diagonals and cross-girders (tension members) were replaced with hollow steel box sections. To analyse these replacements, a finite-element model was created and validated with experimental data. A 200 × 200 × 8 mm steel section (fy = 374 MPa) filled with concrete (fck = 42.5 MPa) was found to be suitable for the top chord members. Buckling and plate yielding analyses of the box sections were also investigated and it was found that, due to the higher stress concentration, only two opposite sides of the plate yielded. A cost comparison revealed that the composite section reduced the overall cost by up to 51% when assuming pin connections and by up to 13% when assuming fixed connections. Furthermore, the effects of joints (hinge and fixed) were analysed to check the critical connection and end failure of the bridge members.