STIFFNESS & ARTICULATION OPTIMIZATION OF METRO RAIL STRUCTURES FOR RAIL STRUCTURE INTERACTION

Abstract

Long Welded Rail (LWR) is commonly used in elevated metro rail bridge structures, where the track is directly fixed on the concrete superstructure or deck. However, there is a significant difference between LWR on the ground and LWR on a bridge. The stiffness of a bridge is lower compared to that of LWR on the ground, leading to deformation under various loads and thermal effects. The interaction between the track and the bridge structure plays a crucial role in determining the final deformations and stresses in the viaduct and track. This interaction, known as the Rail Structure Interaction (RSI) effect, involves force transfer between the rail track and various bridge components, including the superstructure, pier cap, pier, and pile cap. Vertical live loads from trains, braking or traction loads, and thermal effects contribute to this force transfer. In this study, we investigate the stiffness and articulation optimization of metro rail structures for RSI analysis. The analysis follows guidelines from the UIC774-3R Code of Practice (International Union of Railways) and RDSO Guidelines for Rail Structure Interaction Studies on Metro Systems Ver 2. We consider multi-span bridges with different span configurations and superstructure types (such as I-girders and U girders). Key parameters include the axial stresses in the rail, relative displacement between the rail and superstructure, and support or bearing reactions transferred to the bridge components. The software used for analysis is Midas Civil. Our findings indicate that considering the stiffness of piles and piers can reduce axial stresses in the rail and forces at the bearing levels.