The present study is part of the Long Term Bridge Performance Program (LTBP) funded by the Federal Highway Administration. The objectives of this program are to create a comprehensive database of quantitative information of the long-term performance of selected pilot bridges and to develop a methodology to assess bridge performance. Finite element (FE) modeling of the pilot bridges is an intrinsic part of the LTBP program and is intended to not only assist with instrumentation decisions, but also to provide further insight into the behavior of these bridges, which cannot be achieved solely from field testing of the bridges. This thesis provides a comprehensive study of a plethora of issues associated with the development of reliable and accurate FE models of bridges. The first objective of this investigation was to develop reliable finite element models with a variety of levels of refinement and to study the effect of the inclusion of various bridge parameters in the model, such as bridge skew, degree of composite action, thermal gradient and level of support restraint, on the response of bridges. First, the suitability of different modeling techniques and of elements used to model the primary bridge components was assessed using simple models for which analytical solutions are readily available. From these studies, it was concluded that shell elements are adequate to model the bridge deck, and beam and shell elements are both satisfactory to model the bridge girders. From the dynamic analyses of theWildcat Creek River Bridge and the Colquitz River Bridge, flexural modes of vibration were found to be highly sensitive to support restraints and to how the guardrails were modeled and less sensitive to the inclusion of bracing and thermal gradients in the model. The finite element models using extreme boundary conditions were successful in bracketing the field response. The factors identified from these analyses were considered in the analysis of the Virginia pilot bridge. Different support restraints, and the inclusion of skew and level of composite action in the model had noticeable impact on both the static and dynamic responses of the bridge. The results from these analyses were used to assist with instrumentation decisions prior to field-testing. The developed model will also be used to help researchers further understand the bridge's behavior and to help explain a variety of phenomena observed in the field. / Master of Science

This thesis examines the development of a superstructure for a slab-on-girder wood-concrete composite highway bridge. Wood-concrete composite bridges have existed since the 1930's. Historically, they have been limited to spans of less than 10 m. Renewed research interest over the past two decades has shown great potential for longer span capabilities. Through composite action and suitable detailing, improvements in strength, stiffness, and durability can be achieved versus conventional wood bridges. The bridge makes use of a slender ultra-high performance fibre-reinforced concrete (UHPFRC) deck made partially-composite in longitudinal bending with glued-laminated wood girders. Longitudinal external unbonded post-tensioning is utilized to increase span capabilities. Prefabrication using double-T modules minimizes the need for cast-in-place concrete on-site. Durability is realized through the highly impermeable deck slab that protects the girders from moisture. Results show that the system can span up to 30 m while achieving span-to-depth ratios equivalent or better than competing slab-on-girder bridges.

This thesis examines the development of a superstructure for a slab-on-girder wood-concrete composite highway bridge. Wood-concrete composite bridges have existed since the 1930's. Historically, they have been limited to spans of less than 10 m. Renewed research interest over the past two decades has shown great potential for longer span capabilities. Through composite action and suitable detailing, improvements in strength, stiffness, and durability can be achieved versus conventional wood bridges. The bridge makes use of a slender ultra-high performance fibre-reinforced concrete (UHPFRC) deck made partially-composite in longitudinal bending with glued-laminated wood girders. Longitudinal external unbonded post-tensioning is utilized to increase span capabilities. Prefabrication using double-T modules minimizes the need for cast-in-place concrete on-site. Durability is realized through the highly impermeable deck slab that protects the girders from moisture. Results show that the system can span up to 30 m while achieving span-to-depth ratios equivalent or better than competing slab-on-girder bridges.