2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference

A Landmark Concrete Arch Bridge with an Innovative Approach: Post-tensioned Tie Girders

Ms. Luiza Curzio, Ryerson University - Civil Engineering (Presenter)
Mr. Shayan Farahani
Mr. Ahmed Abuzour
Ms. Tanzim Arefin
Dr. Sameh Salib, Ryerson University
Dr. Khaled Sennah, Ryerson University

One of the oldest datable arch bridges was the Mycenaean bridge in Greece, built approximately 1300 BC. The curved geometry enables arch bridges to transfer their weight and carried loads along its curved load path to supports; a simple yet a quite robust mechanism. This distinctive characteristic is what makes the arch bridges one of the most popular bridges of all times. For the present project, the Greater Toronto Area (GTA) needs a bridge to carry both pedestrian/bikers and vehicular traffic over a water stream that passes through a scenic valley/woods. The project investigates two superstructure alternatives; a Bow-string concrete arch bridge (as a high aesthetically pleasing structure) and a side by side CPCI Box Girders alternative (as a conventional design/construction bridge type). The design work is divided in two phases. The first phase (preliminary design) includes a simplified analysis, design and quantity/cost estimation of each alternative. A comparison is performed based on a criterion that accounts for various aspects such as cost, durability, aesthetic and traffic impacts. Due to the nature of the project site, the highly aesthetic requirements of a landmark structure as such, the arch bridge is chosen as the preferred alternative. The second project phase (detailed design) focuses on refinement of the applied loads and analysis to provide detailed design and drawings for the respective bridge. Through this phase and in order to optimize the design and costs of the arch bridge, a post-tensioning system is introduced to the arch tie girders. Such unique approach improves the bridge stiffness and induces both compressive stresses and upward deflection (camber) in the tie girders. This significantly reduces both the potential for tensioning/cracking and the final bridge deflection. In other words, it lessens the long-term repair/maintenance and improves the appearance of the bridge during its service life. The present paper details the subject project and the approach to optimize the cost along with improving the aesthetics, performance and the overall sustainability of the subject bridge.