Design Optimization and Monitoring of Joint-less Integral and Semi-Integral Abutment Bridges in Nebraska

There are more than 9,000 integral abutment bridges and 4,000 semi-integral abutment bridges in the U.S., which increased dramatically in the past two decades (White 2nd, 2007). Nebraska is no exception – there are hundreds of integral and semi-integral abutment bridges in the state of Nebraska, and thus guidelines and specifications for these structures listed on the Bridge Office Policies and Procedures (BOPP, 2016). The obvious advantage of using integral abutment bridges is their reduced construction and maintenance costs by eliminating bearings and expansion joints that make the bridge “joint-less”. This also fits well with Nebraska's "well-timed" bridge preservation practice of eliminating problems before they occur. Despite the wide acceptance in usage (more than 40 States are using integral abutment bridges) and the advantage listed above, integral and semi-integral abutment bridges are often built with specific limitations under each State’s bridge design manuals; and the design primarily relies on limited empirical data. Noticeably, small numbers of problems were reported because these bridges were built within limitations of specific skew angles, pile types, span lengths, and construction practices to name a few. The research objective of this project is to monitor the integral and semi-integral abutment bridges in Nebraska to: 1) obtain data for future design and construction practices for wider applications (longer spans, increased skew angles, improve design details in connections), 2) thoroughly understand the complex long-term behavior of soil-structure interactions (interaction between deck/abutment connection, soil/pile behavior both in integral and semi-integral bridges, backfill/abutment), and 3) better maintain existing structures (repair and strengthen if needed). The multidisciplinary team of structural and geotechnical engineers will carefully investigate the loads produced in abutments over the Nebraska integral abutment bridges, measure the load displacement of piles with fiber optic sensing, examine ratcheting effects (passive pressure increase and inward residual displacement) and voids or settlement under approach span of these structures.