Live Load Distribution and Dynamic Amplification on a Curved Prestressed Concrete Transit Rail Bridge

Abstract

A recently constructed and commissioned in-service light rail transit bridge in Denver, Colorado was examined analytically and via field testing to study its live load performance. The bridge is a four-span horizontally curved structure, composed of chorded prestressed concrete bulb tee girders. The bridge was designed following the American Railway Engineering and Maintenance-of-Way Association (AREMA) guidelines from the Manual of Railway Engineering, which do not explicitly address transit rail structures. In-situ load testing and calibrated finite element analyses were conducted to study the live load performance and determine the effects of speed and centrifugal forces on dynamic amplification and live load distribution. Field-testing and model results indicated variations in live load distribution and amplification as train speed increased. In addition, live load distribution and amplification values differed from results determined using equations from AREMA and the AASHTO guidelines, documents that are commonly used to assist analysis and design due to a lack of available provisions tailored to transit rail bridges.