Analysis Of The ODOT Bridge Inspection Manual
explanatory Essay
1277 words
The ODOT Bridge Inspection Manual ( ODOT, 1973)was used to rate the condition of the AWB (Burgess & Nipple, Inc., 2008). Condition rating for protective coating system of suspension components was 6 indicating greater than 5% and less than 10% of the total protective coating system has failed. The main cables individual rating was 2, which is classified as fair condition and the suspension part of the bridge was classified as satisfactory with rating of 6. The following are the locations suggested to be inspected thoroughly based on deficiency in main cables with water retention being prime cause:
• Downstream Cable at panels: 5, 7-11, 14-18, 23, 25, 27, 30, 32-35, 39, 41-46, 48, 49, 51, 55-58, 60, 63
• Upstream Cable at panels: 5-8, 10, 20, 37, 41, 43, 44-47, 50, 55-60, 62
The most recent inspection was the one carried out in November, 2012. Modjeski and Masters (2013) performed the inspection in accordance to NCHRP-534 (Mayrbaurl & Camo, 2004). The inspection was carried on total of four panels from where a total of 13 wire samples were cut and taken for laboratory testing. While conducting tensile test on these sample wires, the ultimate failure strain was not recorded. Therefore, the ‘Ductile Wire Method’ of cable strength prediction could not be applied and the ‘Brittle Wire Method’ was used to estimate the factor of safety of the main cables. However, as there is no evidence of wire break, the wires are possibly more ductile than assumed and ‘Brittle Wire Method’ could have underestimated the safety factor. The samples from only 4 panels were statistically unreliable based on NCHRP-534.
The Cable Strength Evaluation Report (Modjeski & Masters, Inc., 2013) estimated the controlling factor of safety to be 2.41 which will rea...
... middle of paper ...
...ial secondary/ noise acoustic emission sources and lastly, the fifth experiment simulates a wire break which is the primary source under concern.
Chapter 4 – Review of Data from AWB: The knowledge gained from literature review and laboratory experiments has been utilized in analysis of recorded data from AWB. Description on the installed AE system is presented. A detail analysis of the data from June 2013 for both north and south cable is presented followed by a summary of analysis results from previous four months. It also includes data analysis from the invasive inspection period of 2012.
Chapter 5 – Conclusions: This chapter summarizes the results from the study and provides recommendation for future works. Suggestions for improvement of the monitoring system are provided. In addition, insights are provided for developing improved laboratory testing strategies.
In this essay, the author
- Explains that the odot bridge inspection manual (odot, 1973) was used to rate the condition of the awb.
- Explains that modjeski and masters (2013) performed the inspection in accordance with nchrp-534. the 'ductile wire method' of cable strength prediction could not be applied.
- Explains that the cable strength evaluation report (modjeski & masters, inc., 2013) estimated the controlling factor of safety to be 2.41 which will reach action level safety factor 2.15 in 2025.
- Explains the installation of an acoustic monitoring system to monitor the cables of the awb. the system listens for potential wire breaks and locates it in time and space.
- Explains that the 82-year-old awb is undergoing an extensive rehabilitation starting in construction season 2014 so that its useful life will be extended.
- Describes the objectives of the study: review the literature on application of ae in bridges; perform laboratory experiments; and understand acoustic sources.
- Explains that the primary goal of the ae monitoring system installed in the main cables of awb is to listen for wire breaks.
- Analyzes how the number and frequency of wire breaks indicate cable condition degradation and auto sensor test can be used to check the performance of ae system.
- Explains the ae monitoring system uses a specially designed classifier to discriminate wire break from pool of signals.
- Describes the chapters in the thesis, including an overview of the project, a literature review, and laboratory experiments to understand working principle of ae and signal properties.
- Explains that the knowledge gained from literature review and laboratory experiments has been utilized in analysis of recorded data from awb.
- Summarizes the results from the study and provides recommendations for future works. suggestions for improvement of the monitoring system and insights are provided for improving laboratory testing strategies.
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