About the research
Lateral slide-in bridge construction, also referred to as slide-in bridge construction (SIBC), has gained increasing attention as a viable accelerated bridge construction (ABC) approach. The use of SIBC is one of several ABC methods being promoted through the Federal Highway Administration (FHWA) Every Day Counts (EDC) program. The Iowa Department of Transportation (DOT) completed its first lateral slide-in bridge project in the fall of 2013 during the replacement of a single-span bridge on IA 92 over a small stream just west of Massena in southwest Iowa.
After that, the Iowa DOT planned to construct a multi-span bridge using slide-in construction techniques, which raised many questions. As such, it was vitally important that Iowa DOT design engineers have the best information regarding the performance of various critical details. The addition of more spans creates a more complex system that requires connections (and other details) that were previously not needed in a single-span slide. Furthermore, the fact that the multi-span bridge would need to slide on abutments plus piers (as opposed to just abutments in a single-span case) created possible uplift and overturning scenarios.
The objective of this project was to develop economical and durable design details to be used with the lateral slide concept with a focus on pier connection details. The ultimate goals with this research and the design/construction of the multi-span bridge were to end up with a bridge that is a strong, durable, economical bridge that can be constructed utilizing the lateral slide method and provide modifications to the Iowa DOT’s three-span standards.
The general finding from the field monitoring work was that the current slide-in practice works well with the multi-span steel girder superstructure and the wall pier. No significant response from the substructure was visually observed during the slide-in, and no cracking occurred on the concrete deck or piers. This indicated that the superstructure with steel girders and concrete diaphragms can be built with the lateral slide-in method.
Significant strain was measured from the pile strain gauges. The piles were functionally adequate to carry the vertical load, and the moment carried by each pile was minimal. An uplifting action was captured on Pier 1. However, this effect was minimal on Pier 2.
Based on the results from the work conducted in the four tasks, further research, including laboratory tests and analytical simulation, is proposed as additional Phase II work