Authors: Hari Om Dhar Badgaiyan, Assistant Professor Hariram Sahu
Abstract: Cable-stayed bridges are widely adopted for medium- to long-span crossings owing to their structural efficiency and aesthetic appeal, and the deck girder material strongly influences their stiffness, weight and overall performance. This paper presents a comparative finite element evaluation of a representative 180 m (30 m + 120 m + 30 m) cable-stayed bridge with three deck girder alternatives — reinforced concrete (RC), structural steel, and prestressed concrete (PSC) — modelled in SAP2000 under identical geometry, cable arrangement, support conditions and IRC Class AA loading. Linear static analysis was carried out with the deck material as the sole variable across the three models. Structural response was compared in terms of joint reactions, joint displacements and rotations, internal frame forces, and area-shell stresses. Results show that the steel deck consistently produced the lowest reactions, displacements, internal forces and stresses owing to its high strength-to-weight ratio; the RC deck exhibited intermediate global response but the highest tensile stress; and the PSC deck attracted the largest internal forces and vertical reactions yet achieved the lowest tensile stress because of prestressing. An indicative life-cycle cost comparison further shows that RC offers the lowest first cost, steel the highest, and PSC the most favourable long-term economy. The findings provide practical, results-based guidance for deck-material selection in cable-stayed bridge design.
