Structural Health Monitoring & Condition Assessment of Chulitna River Bridge

AIDC project number: 510015


Leroy Hulsey

  • Alaska DOT
  • Alaska Railroad
  • Start Date: Sep 1, 2012
  • End Date: Dec 31, 2012

Project Summary

The Chulitna River Bridge, built in 1970, is located at Historic Mile Post 132.7 on the Alaska Parks Highway between Fairbanks and Anchorage, Alaska. The Parks Highway is the most direct route connecting Anchorage, Fairbanks, and Prudhoe Bay. Heavy overload vehicles with loads up to 410,000 pounds regularly travel this route. The original bridge was 790 feet long, with five spans and is a continuous bridge with two exterior steel plate girders and three sub-stringers. It had a cast-in-place concrete deck 34 feet wide. In 1993, the bridge deck was increased to 42 feet 2 inches by replacing the original cast-in-place deck with precast concrete deck panels. To accommodate the increased loads, the two original exterior plate girders were strengthened, three new longitudinal steel trusses were installed utilizing the original stringers as top chords, and steel bracing was added to the piers. In August, 2012, the research team will design and install a real time fiber optic structural monitoring system on the bridge to determine if the girders are over-stressed for standard highway loads and permit vehicles. The final working thresholds will be established for automated notification if changes occur in structural response or established thresholds are exceeded. After September 2012, the research team will continue monitoring and analyzing the experimental data until December 31, 2013. The test results will be used to identify changes in load distribution for the girders and trusses. It will also be used to identify if structural changes occur. Further, the information will be used to provide alerts when sensing systems approach or exceed established limits. It will also be used to develop a protocol to apply an SHM program to bridge monitoring on other bridges in Alaska.