Smoothness Estimation of Super-large Bridges in Railway Line Based on Fitting Railway Plane and Profile

Reasonable evaluation of the flexural deformation of long-span bridges is the basic precondition of guaranteeing service stability and comfort of trains. Considering the limitations of the current evaluation index, the deflection-span ratio, such as the effects of deflection on railway plane and profile being ignored, a new methodology that uses the least-square method to fit the deformation curve into the standard railway line in plane and profile first and then evaluates the smoothness of railway super-large bridge by the Code for Design of Railway Line, was proposed. This method was applied to the engineering example of Wufeng Mountain super-large bridge for validation. Results show that under the worst load conditions of system vibration, the minimum radii of the vertical curve and plane circular curve are 29.3 km and 54 km, respectively, which conform to specification requirements. Setting up a vertical arch can neutralize the vertical deformation to some extent, and is beneficial to keep the regularity of track. The proposed method could evaluate the deformation of bridges properly from the aspect of railway smoothness and is applicable to instruct the design of long-span bridges and ensure the safety of railway operation.