Link to Report: Final Report
Background :
The continuity of steel girders in a multi-span bridge system is achieved by splicing girders at locations where moment demand is lower (between 1/3 or 1/4 of span length). For a conventional construction sequence of a continuous steel bridge system, the deck is cast in place after the launching of the steel girders. An alternative to this conventional construction is the simple for dead load and continuous for live load (SDCL) system. In the SDCL steel bridge system, girders are placed over supports (abutments and intermediate piers). The girders are connected to the adjacent girders using a concrete diaphragm so that the girders behave simply supported under dead loads and become continuous under superimposed dead and live loads after hardening the concrete diaphragm. SDCL steel bridge system can be constructed using conventional methods where the deck is cast-in-place; however, the system’s merits can be embraced by using precast deck panels or a modular approach for accelerated bridge construction (ABC) applications.
Most in-service steel bridges develop corrosion problems due to leakage at joints, increasing uncertainty regarding their structural performance. Also, during the periodic inspection of steel bridges, special emphasis is given to connection elements (such as splices), which increase the cost and time of these inspections. For SDCL systems, the connection between the girders and the intermediate pier (the diaphragm) encases and protects the end of the steel girders, thus resulting in improved service life. Furthermore, using an SDCL steel bridge system eliminates the field splices and the deployment of additional cranes and shoring. This results in a reduced impact on intersecting traffic.
Objectives :
The overall objective of this project is to develop a practical UHPC-based continuity connection for SDCL steel bridge systems that simplifies connection detailing, improves construction tolerances and durability, and is applicable to both non-seismic and seismic bridge configurations.
Scope :
Task 1 – Literature Review and Synthesis.
The research team will conduct a comprehensive literature review with a focus on the uses of SDCL using NSC. The review will cover traditional detailing of connections, testing methodologies, finite element modeling, and performance predictions using simplified expressions.
Task 2 – Develop and Validate the Numerical Modeling Framework.
Nonlinear finite element models will be developed for steel, NSC, UHPC, reinforcement, and their interfaces. Furthermore, validation of the modeling approach using available experimental data from previous SDCL and UHPC studies will be performed.
Task 3 – Perform Parametric Evaluation and Refine the Connection Details.
This task will evaluate the effects of key design parameters, including girder-end gap, diaphragm dimensions, seat height, end plates, reinforcement, and steel-to-UHPC anchorage, and refine the proposed connection details for gravity and seismic loading conditions.
Task 4 – Develop Design and Implementation Recommendations.
A final report will be presented that will present the establishment of preliminary design requirements, construction procedures, durability considerations, seismic capacity-protection requirements, and an implementation checklist for future applications of the proposed UHPC SDCL connection.
Research Team :
Principal Investigator: Atorod Azizinamini, Ph.D., P.E.