Structural design and lifecycle analysis of an orthotropic steel deck bascule bridge

This study presents the structural design and lifecycle analysis of an orthotropic steel deck (OSD) bascule bridge in Viareggio (Italy), considering various operational states and constraints. The analysis varied the bridge's opening angle in 15-degree increments from 0 to 90 degrees, using two steel grades, S355 and S450, by comparing hydraulic or electro-mechanically driven activation mechanisms. The findings reveal that as the static model transitions from pinned-pinned to cantilevered when the bridge is opened, the structural demand for bending moment and shear force increases, with a maximum of nearly 15°–30°. At the same time, axial forces shift from tensile to compressive. Structural design has been carried out using higher grade steel (S450), which has led to a 17.17% mass reduction, cost savings of 3.4%, and a notable decrease in CO2 emissions by 16%. This proves that despite using higher-grade steel characterized by more significant CO2 emissions, the mass reduction associated with the refined design leads to an overall lower environmental footprint. This fact underscores the importance of selecting proper steel grades for steel to achieve an optimal trade-off between CO2 emissions and mass reduction.