Finite Element Analysis of Various Bridge Types under IRC Vehicle Loading Conditions

Abstract

The accurate characterization of structural response to a standardized vehicle loading forms a key requirement within the field of infrastructure engineering today. This research introduces three types of bridge structure geometry – the deck slab bridge, the cable-stayed bridge and the cable suspension bridge – which are all set to 200 m span and 10 m carriageway width and are analysed using three-dimensional finite element analysis (FEA). All the models were designed and studied in STAAD.The analysis was carried out using Pro with Indian Road Congress Class 70R vehicle loading following IRC:6-2014 with all abutment supports pinned. Maximum bending moment (kN-m), shear force (kN), axial force (kN), nodal deflection (mm) and vertical support reactions (kN) are key structural response parameters evaluated. A material quantity based cost analysis has also been carried out with the latest Schedule of Rates (SOR) for concrete at Rs. 4,200 per m3. The results show that the cable suspension bridge has the minimum bending moment in the load span (204.54 kN-m, 30.7% reduction compared to the deck slab bridge) and the minimum deflection (2.935 mm, 63.1% reduction compared to the deck slab bridge), which prove that the cable suspension bridge is more efficient in flexural resistance and serviceability than the deck slab bridge. The lowest shear force is 281.952 kN (required for deck slab bridge) and the lowest axial force is 4,583.729 kN (required for deck slab bridge). The most feasible solution is the cable-stayed bridge as it requires the least quantity of concrete (705.695m3) and thus gives a cost saving of about Rs. 4.07 lakh (12.1%) over the deck slab bridge. All three typologies meet the IRC:6-2014 "serviceability deflection limit" of L/800 = 250 mm, and the factors of safety are greater than 31. The results offer a quantitative decision matrix based on evidence that can be used in bridge type selection in Indian infrastructure context.

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