Parametric Analysis of Vertical and Lateral Stiffnesses of Long-span Road-rail Suspension Bridge

The factors influencing the vertical and horizontal stiffness of high-speed and heavy-haul road-rail suspension bridges require further study given their increasing popularity in China. In particular, the suitability of existing technical standards that address the effects of heavy train live loads operating at high speed on operational security and passenger comfort requires investigation. This paper compares the regulations in China's general bridge codes with other international codes for the design of railway suspension bridges. The key parameters of the road-rail suspension bridges are: (a) bridge lengths of 1000 m; (b) speeds of _250 km/h for passenger trains and 120 km/h for freight trains; and (c) live loads of 64 kN/m. A parametric study is presented for a road-rail suspension bridge with a main span of 1196 m that investigates the effects of different support systems, arrangements of auxiliary piers, span-to-height ratios, and span-to-width ratios on the vertical and lateral stiffness of the bridge. The values of these parameters are proposed. It is demonstrated that the proposed long-span suspension bridge scheme is technically and economically feasible, providing sufficient horizontal and vertical stiffness to assure adequate passenger comfort.