Iowa Department of Transportation
Iowa Highway Research Board
Behrouz Shafeishafei@iastate.edu email >
Structural Engineer, BEC
Brent Pharesbphares@iastate.edu email >
Bridge Research Engineer, BEC
About the research
The secondary road system in Iowa is vitally important to the movement of goods and people throughout the state. In some cases, secondary roads serve as feeders to the primary road system and then on to the National Highway System. In other cases, the secondary road system serves as a critical link for farmers as they move their crops. With approximately 20,000 bridges on the secondary system, county engineers are faced with the ever more difficult task of maintaining and replacing those bridges.
In an effort aimed toward identifying alternative bridge systems, especially for bridges with shorter span lengths, this research project focused on a new bridge girder/deck section that consists of a single T-shape. The individual T-shape sections are connected together using a cast-in place ultra-high performance concrete (UHPC) longitudinal joint. Additionally, the proposed section uses commercially available, corrosion-resistant, reinforcing steel, which has tensile strengths in the order of 130 ksi.
Through a set of laboratory experiments, the behavior of the individual T-beams and a joint setup made with two T-beams was systematically tested in this project under service limit loads for flexure and shear stress. The experimental test results were then utilized to validate finite element (FE) models created using the Abaqus software package. The FE models were employed to investigate the behavior of the joint under various loading scenarios.
The results from the experiments and FE simulations showed that the proposed joint detailing and bridge system performed well under service limit loads for both flexure and shear. With the combination of strength and durability advantages introduced, the outcome of this research project is expected to help county engineers consider the new bridge system developed as a promising alternative for short-span bridges.