摘要: |
This report presents the BTC method; a comprehensive state-of-the-art methodology for evaluation of remaining strength and residual life of bridge cables. The BTC method is a probability-based, proprietary, patented, and peerreviewed methodology, which applies to parallel and helical; either zinc-coated or bright wire of suspension and cablestayed bridge cables. The BTC method includes random sampling without regard to wire appearance, mechanical testing of wires, determining the probability of broken and cracked wires, evaluating ultimate strength of cracked wires employing fracture mechanics principles and utilizing the above data to assess remaining strength in each investigated length of the cable. The probabilistic-based BTC method forecasts remaining service life of the cable by determining the rate of growth in broken and cracked wires proportions detected over a time frame, measuring the rate of change of fracture toughness over same time frame, and applying the rates of change to a strength degradation prediction model. The BTC method provides sensitivity analysis to identify the key inputs, which influence the estimated cable strength and assist decision-making process. The report describes the application of BTC method at Mid-Hudson Bridge in Highland, New York, conducted by Bridge Technology Consulting (BTC), under a joint contract with New York State Department of Transportation (NYSDOT) and New York State Bridge Authority (NYSBA). This project is funded in part with funds from the Federal Highway Administration (FHWA). The BTC method has been peer-reviewed by MTA Bridges & Tunnels, NYSDOT and NYSBA. To date, the BTC method has been applied to evaluate cable strength at the Bronx-Whitestone Bridge and Mid-Hudson Bridge, in the state of New York, USA. |