Case Study on Major Elements of an Elevated Metro Bridge

Abstract

Metropolitan rail systems are critical urban transportation infrastructure, and elevated metro bridges using box girders and piers form their structural backbone. This paper presents a comprehensive case study on the major structural elements of an elevated metro bridge, focusing on pier design and box girder analysis. The first phase develops pier design using both force-based and direct displacement-based seismic design methodologies, comparing their performance predictions. The second phase conducts parametric finite element analysis of box girder bridges evaluating Single Cell, Double Cell, and Triple Cell configurations. Parameters including radius of curvature, span length, and span-to-radius ratio are varied to assess longitudinal stresses, shear, torsion, moment, deflection, and fundamental frequency. Results demonstrate that displacement-based design provides 18% more accurate seismic performance prediction than force-based methods, and Double Cell box girders offer the optimal balance of structural efficiency and construction economy for standard metro spans.