PennDOT Instrumentation & Monitoring of PA Bridges

Statewide, PA

AI Engineers, Inc. (AI) is currently working with PennDOT to instrument and monitor 10 bridges owned and maintained by the DOT. These bridges range from simple span box beams to the Elizabeth Bridge (1,500 ft. long with 13 approach spans along with a 3-span continuous thru truss with a 450-ft.-long main span with a cable suspended roadway). 

The entire project uses wireless monitoring equipment and gauges, which significantly reduces installation and maintenance costs associated with wired systems. AI is responsible for all project management, coordination (PennDOT, vendors, etc.), scheduling, and quality assurance/quality control. AI provided access to each bridge for the installation of the equipment and prepared site-specific Maintenance of Traffic Plans for each bridge.

In addition, AI provided load testing as part of the project. The load testing included coordinating with a hauler, ensuring the appropriate truck configuration (axle spacing and weights), and working with PennDOT to determine a loading sequence. The load tests were monitored in real time using strain gauges, allowing AI and PennDOT engineers see the live effects immediately as a truck of a known weight and configuration crosses the structure. Cable vibration sensors were installed and used to determine the tension in each cable.

The AI Team is specifically providing PennDOT services to monitor the following conditions:

  • Barge collision: monitoring vibration on the piers and detecting collision (through detection of shocks and high acceleration events), simultaneous and synchronous monitoring of tilt/orientation on the piers, further confirmation through camera footage.
  • Evaluating the performance of deck replacements and hybrid shear connectors in prestressed box beam bridges. Evaluating steel retrofits: using strain sensors to accurately monitor thermal and live load-induced loading effect on the retrofits. Conducting statistical/comparative analysis in SenScope software.
  • Post-heat-straightened performance evaluation: Use a combination of wireless strain SenSpots and high-precision tilt.
  • SenSpot sensors on post-heat-straitened members; conduct analysis on strain data (both thermal and live-load response); use precision tilt SenSpot sensors to monitor change in curvature (deformation) of the members; conduct comparative analysis on response of the repaired members with identical members with no damaged to quantify the effectiveness of the repair.
  • Critical movement for stone masonry arch bridges: use a few high resolution tilt SenSpot sensors; the devices have a resolution of 0.00016 degrees and they are capable of detecting and tracking movements caused by temperature, settling, or hydraulic damage in scour critical bridges.
  • Detecting flaws as small as 1mil: Use an array of strain SenSpot sensors to detect damage anywhere in a steel member; conduct regression analysis on long-term stain measurements to detect flaw. The analysis includes thermal response (e.g., the response of the structure to temperature change) as well as the response to live load.

Highlights 

  • Client: PennDOT
  • Duration: 2016-Current
  • Project Scope:
    • Wireless structural monitoring
    • Remote monitoring 
    • Detecting flaws as small as 1mil
    • Detecting and tracking movements caused by temperature, settling, or hydraulic damage in scour critical bridges
    • Project management
    • Statistical/comparative analysis