Updating the AASHTO LRFD Movable Highway Bridge Design Specifications (2021) / Chapter Skim
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5 C H A P T E R 2 Literature Review and Survey Literature Review Synthesis Mr. Jim Phillips of Hardesty and Hanover led the effort of gathering references relevant to the project objectives.
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6 h) Identified AASHTO LRFD provisions that could be adapted for RBM design.
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7 Document Level of RBM Usage Comments BS EN 1090-2: Execution of steel structures and aluminum structures, Part 2: Technical requirements of steel structures RBM Limited to structures Canadian Highway Bridge Design Code CSA S6-14, Chapter 13 Limited-RBM Refers to reliability for fatigue design; refers to B10 and L10 life for bearings and bearings in speed reducers CMAA Specification No. 70-2004 Specifications for Top Running Bridge & Gantry Type Multiple Girder Electric Overhead Traveling Cranes Minimum-RBM Includes provisions for load factors, but design is based on allowable stress and/or fatigue DIN 19704: 1998.
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8 Modes and Effects Analysis (FMEA) applying the concept of severity ranking on a scale of 1 to 10, with 1 indicating no loss of function and 10 representing the loss of human life.
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9 Document Disciplines Included Movable Bridge Components Included IEEE 352-2016 - IEEE General Principles of Reliability Analysis of Nuclear Power Generating Systems and Other Nuclear Facilities Electrical Electrical power systems NEN 6787 The Design of Movable Bridges – Safety Structural, Mechanical, Hydraulic, Electrical Focus on hazards (OSHA-type) and operational guidelines (e.g., visibility, sequence, etc.)
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10 • Loads that impact the sizing of the prime mover, including partial factors. • Loads used to design drive machinery for both mechanical and hydraulic systems, including partial factors.
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11 IEEE 352-2016 - Institute of Electrical and Electronics Engineers (IEEE) General Principles of Reliability Analysis of Nuclear Power Generating Systems and Other Nuclear Facilities: There was not much information in this standard relative to movable bridges that was not covered in IEEE 493-2007.
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12 Summary and Knowledge Gaps The documents reviewed that were based on RBM or a similar concept and offered the most information relevant to NCHRP 12-112 are AGMA 2001-D04, ABMA 14:2014, BS (NEN)
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13 3) Supplemental / Follow-up Condensed results of the interviews are presented with descriptive commentary, graphs, and tables.
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14 All respondents indicated that the six factors presented were acceptable, and no other factors were suggested (Figure 3)
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15 Figure 5. Operating Wind Restrictions Figure 6.
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16 Table 3. Condensed Summary of Part 1 Data Reliability Survey Part 2 of the interview deals with the reliability that the bridge owners have experienced with the various bridge types, systems, and components required for operation.
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17 This rating scale along with typical design service life of various systems was reviewed at the time of interview to emphasize a consistent understanding of the ranking. The results of Part 2 of the interviews follow.
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18 2. How would you rate the reliability of movable bridge drive machinery systems and components on your movable bridges?
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19 4. How would you rate the reliability of movable bridge electrical power and control systems on your movable bridges?
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20 6. Approximately how many movable bridges are included in the assessment?
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21 The following two graphs present a condensed summary of the Part 2 reliability data. The grouping below in Figure 14 indicates that there may be some minor respondent scoring bias.
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22 A condensed summary of the data from Part 2 of the interview is included below in Table 4 for additional reference. For more detailed information, see Appendix B
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23 Figure 17. Distribution of Single and Double Leaf Figure 18.
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24 2. How frequently do your bridges open?
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25 4. What causes more of your disruptions in operation, electrical or mechanical issues?
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26 Note that typical electrical restoration times are much less than mechanical. On average, mechanical time was 14 hours, while the electrical was 1.4 hours.
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27 11. Are there any bridge types you think are more or less reliable than others?
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28 Summary of Findings The results of the interviews confirmed the experience of those on the RT that have been working in the movable bridge industry for decades. The overall reliability of movable bridges is providing acceptable service.
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