Three-Year Evaluation of Thermally Induced Strain and Corresponding Lateral End Pressures for a GRS IBS in Ohio

Abstract

Geosynthetic-reinforced soil (GRS) integrated bridge systems (IBS) integrate conventional bridge superstructures with a GRS abutment foundation and GRS approach for a cost-effective, rapid construction alternative. A 42.7 m long single span GRS IBS was constructed and instrumented to monitor the thermally induced behaviors and better understand the interaction between the superstructure and substructure within the limits of this system. Strain gauges were attached to the steel girders, and lateral end pressures were monitored using earth pressure cells to determine the level of stress thermally induced in the GRS approach over a 3.5 year monitoring period and evaluate the rigidity of the boundary conditions that exist at the interface. During this 3.5-year monitoring period, the data show that the GRS approach is engaged with the superstructure and experiences both active and passive lateral pressures during each thermal cycle without displaying an increase in passive pressure with time. The stress-strain data acquired during this project indicate that the GRS IBS is behaving significantly more like a system with unrestrained boundaries due to the flexibility of the GRS approach at each end. The tightly spaced reinforcements create a composite material at the ends of the superstructure that enable the approach fill to move successfully with thermally induced superstructure deformations without creating a failure within the soil or at the surface of the roadway (interface included).