Evaluation of Prestressed Concrete Bridges under Light Rail Loading

Abstract

This paper presents the evaluation of prestressed concrete bridges carrying light rail loading, which is significantly unexplored relative to bridges subjected to conventional heavy-haul and highspeed trains. Four bridges in Denver, CO, are selected to investigate static and dynamic responses, including flexural behavior, passenger occupancy, statistical properties, live load distributions, natural frequencies, and user comfort. Three-dimensional finite element models are developed to complement in-place findings. The measured train loadings are statistically stable along with Gaussian distributions and increase by 10.8% when their average operating speed rises from 32.9 to 49.0 mph (53 to 78 kmh). Passenger loading that is stochastic in nature also increases the train loading by 23.3%, on average. Existing design approaches for live load distributions deviate from those attained from the field, which is particularly noticeable for interior girders. Deflection control criteria used in practice are not applicable either. In accordance with the deflection and frequency of the bridges, the user comfort of light rail systems (pedestrians and passengers) is assessed. Statistical properties are acquired and characterized, which are valuable when developing design guidelines.