The BTC method is a comprehensive, probabilistic, state-of-the-art, and patented methodology that employs random sampling, principles of fracture mechanics, and statistical analysis for strength evaluation of bridge cables, which applies to parallel and helical; either zinc-coated or bright wire of suspension and cable-stayed bridge cables.
The BTC method provides accurate assessment of the proportions of broken and cracked wires, and forecasts service life of the bridge cable using degradation kinetics; thus providing invaluable information regarding budgeting and future inspections. These assist bridge owners in strategic planning and decision-making.
The BTC method is published in the following manuals, published and co-sponsored by the U.S. Federal Highway Administration (FHWA):
- Primer for the Inspection and Strength Evaluation of Suspension Bridge Cables, U.S. Department of Transportation, Federal Highway Administration, Publication No. FHWA-IF-11-045, May 2012.
- BTC Method for Evaluation of Remaining Strength and Service Life of Bridge Cables-New York State Department of Transportation, NYSDOT REPORT C-07-11, September 2011.
Recent Applications of the BTC method:
The BTC method was applied for the evaluation of the remaining cable strength of the following bridges:
- Pierre Laporte Bridge, Quebec, Canada
- Forth Road Bridge, Edinburg, Scotland
- Williamsburg Bridge, New York City, USA
- Bronx-Whitestone Bridge, New York City, USA
- Mid-Hudson Bridge, Poughkeepsie, NY, USA
The BTC method for Cable Strength Evaluation was subject to independent peer review by different suspension bridge owners:
- MTA Bridges & Tunnels, New York City
- New York State Department of Transportation
- New York State Bridge Authority
- U.S. Federal Highway Administration (FHWA)
ENDORSEMENTS BY EXPERTS
I have examined your report and it seems reasonable. I think your argument on random selection without regard to appearance is reasonable.
You have actually changed the paradigm of cable strength analysis and testing, and you have identified not only the proper sampling procedure but also defined a correct model of behavior. It is well worth the effort, because it provides answers to the owners of such bridges. You have done a monumental job, and I again congratulate you on the quality and value of your work, as well on your perseverance and ingeniousness.
I have finished reviewing the report and I think it is an exceptionally comprehensive analysis of the problems in the cables of the bridge and can provide the authorities with an excellent basis for scheduling future bridge examinations and other actions to extend its life. The report not only covers all of the factors that go into the evaluation of the bridge wires, which gives it credibility but also provides the reader with the step by step understanding of procedure on which the analysis is based.
Based on this review, my opinion is that the BTC method is a rational and rigorous approach for the evaluation of complicated main bridge cable systems. The field sampling plan, the laboratory test plan, and the analytical methodology incorporating the obtained data are well-documented and clear.