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I-35W St. Anthony Falls Bridge

FHWA/USF Sub-Structure Health Monitoring Research


Project Details

The goal of this program is to show how internal instrumentation can be used monitor and assess the health of bridge foundations. The gages installed during construction can and will be used to show traffic and wind load effects on the pier performance.

This is part of a larger program involving the entire bridge, but at present pertains only to the South Bound Pier 2 columns (interior and exterior) and Shafts 1 and 2 (2SB-1 and 2SB-2, respectively) under the exterior column. Therein, two types of strain gages and thermocouples will be installed to monitor three phases of the bridge/foundation system: (1) internal shaft temperature, (2) construction loads, and (3) long-term health monitoring.

Phase 1 Internal Temperature Monitoring: The internal shaft temperature increase due to the heat of hydration will be monitored for an extended period of time to better understand mass concrete effects in drilled shafts using high performance concrete (in this case Self Consolidating Concrete; SCC). This dovetails with on-going FHWA studies (and others) now addressing mass concrete effects in drilled shafts of all sizes as well as the use of SCC and low heat of hydration mixes to mitigate these conditions.

Phase 2 Construction Load Monitoring: The loads due to construction will be monitored as they increase and are distributed down the length of the shaft. Additionally, by correlating the number of box sections and their respective weights to the measured strain in each column, the column strain gages can be calibrated with increased confidence. These values will also be compared to more traditional means of computing load from concrete modulus and strain in the column.

Phase 3 Long-Term Health Monitoring: Using the calibrations/correlations developed during Phase 2, variations in shaft and column loads can be used to identify aberrant conditions that could then be used to alert officials to take appropriate action.

  • Minnesota Department of Transportation Project Details


    • Health Monitoring Pier 2 Health Monitoring Pier 2 South Camera Pier 2 Close-up Camera West Camera I35W St. Anthony Falls Bridge Site

    Webcam

  • MnDOT Webcam

    • Real-time Remote Truck Load Test Data

  • All Shaft Strains: Southbound Pier 2


  • Shaft 1 Strains: Southbound Pier 2


  • Shaft 2 Strains: Southbound Pier 2


  • All Columns Strains: Southbound Pier 2


  • Interior Column Strains: Southbound Pier 2


  • Exterior Column Strains: Southbound Pier 2


    • Real-time Remote Data

  • All Shaft Strains: Southbound Pier 2


  • Shaft 1 Strains: Southbound Pier 2


  • Shaft 2 Strains: Southbound Pier 2


  • All Columns Strains: Southbound Pier 2


  • Interior Column Strains: Southbound Pier 2


  • Exterior Column Strains: Southbound Pier 2


  • High Speed DAS Battery Voltage


  • Thermocouple Data: Southbound Pier 2 Footer Temperature


  • Data Logger Battery Voltage


  • Strain Gage Data: Southbound Pier 2



    • Archived Data

  • Strain Data with Corresponding Daily Photos


  • Pier 2 Southbound Time Lapse Photos


  • Pier 2 Shafts 1 and 2 Internal Temperature Traces