Maximizing Inspection Cycles Utilizing Steel’s own Material Properties to Arrest Cracks as an Effective Adjunct to NDE

Cracking in steel bridges is a common occurrence and necessitates periodic inspection to detect cracks. If detected, crack arrest holes (CAH) are commonly drilled at the tip of the crack and then monitored using NDE to verify crack arrest. These CAH are frequently ineffective in retarding crack growth and therefore may require more frequent inspection. An innovative aerospace derived technology, StopCrackEX, radially expands a high interference fit bushing into a hole drilled ahead of the crack tip. Besides creating a high interference fit in the hole, it also induces a compressive residual stress around the hole that shields the hole from cyclic loads. Tests confirm its effectiveness in arresting crack growth in typical bridge steel. The process is reviewed explaining how the inherent material properties enhance the fatigue and crack growth life and make the CAH more effective, and reduce the need for frequent re-inspection. As an effective adjunct to NDE that could be applied at time of crack detection, StopCrackEX could greatly reduce maintenance and repair cost, enhance the integrity of the bridge structure and reduce cost of ownership. Additionally, when NDE is not performed at the same time with the conventional crack repair, the StopCrackEX still offers effective crack arresting.

References
1. Jalinoos, F., P. Haldipur, S. Jin, R. Lui and R. Satyanarayana. “Summary Report on Steel Bridge Testing Program (SBTP) Crack Detection in Steel Bridges,” Draft V. 3, May 20, 2011. 2. Crain, J.S., G.G. Simmons, C.R. Bennett, R.B. Gonzalez, A.B. Matamoros and S.T. Rolfe. “Development of a Technique to Improve Fatigue Lives of Crack-Stop Holes in Steel Bridges,” Transportation Research Record, Journal of the Transportation Research Board No. 2200, Transportation Research Board of the National Academies, Washington, D.C., 2010, pp. 69–77. 3. Reid, L. “Mitigating Bridge Structural Fatigue Cracking Using Aerospace Derived Technology,” New York Bridge Conference. New York, New York, 25-26 July 2011. 4. Reid, L. “Repairing and Preserving Bridge Structure by Innovative Crack Arrest Repair System,” Proceedings of the International Bridge Conference, Paper No. IBC-12-8, Pittsburgh, PA, 2012.
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