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The National Academies

NCHRP 12-115 [Active]

Guidelines for Risk-Based Inspection and Strength Evaluation of Suspension Bridge Main Cable Systems

  Project Data
Funds: $470,000
Staff Responsibility: Dr. Waseem Dekelbab
Research Agency: Modjeski & Masters
Principal Investigator: Dr. Barney Martin
Effective Date: 8/14/2018
Completion Date: 4/13/2021

BACKGROUND
 
Since its publication in 2004, NCHRP Report 534: Guidelines for Inspection and Strength Evaluation of Suspension Bridge Parallel Wire Cables, has become a nationally recognized guideline. Because of the complexity of the technical information presented in the NCHRP Report 534 and the unique nature of suspension bridges, the FHWA published a Primer for the Inspection and Strength Evaluation of Suspension Bridge Cables in May 2012 to supplement NCHRP Report 534. The Primer expanded the information in NCHRP Report 534 and offered additional resources for agencies planning and performing inspections, metallurgical testing, and strength evaluations of suspension bridge main cables. Significant progress has been made by researchers and bridge owners over the last decade to advance risk-based inspection methods, nondestructive evaluation (NDE) techniques, structural health monitoring (SHM), and strength evaluation methods. There is an immediate need to incorporate these advances into the current practices for inspection and evaluation of suspension main cable systems.
 
OBJECTIVES
 
The objectives of this research are to (1) develop guidelines for risk-based inspection and strength evaluation of suspension bridge main cable systems using probabilistic approaches and (2) plan and conduct a workshop for suspension cable bridge owners to demonstrate the use of proposed guidelines. The guidelines shall be presented in a format suitable for adoption by AASHTO. 
 
Accomplishment of the project objectives will require at least the following tasks.
 
TASKS
 
PHASE I—Planning
 
Task 1. Conduct a literature review of relevant domestic and international research and guidelines with consideration to the latest developments in inspection (visual and NDE based), maintenance/preservation, monitoring, and strength evaluation of suspension bridge main cable systems. The domestic review shall include research conducted through the NCHRP (i.e., NCHRP Report 534: Guidelines for Inspection and Strength Evaluation of Suspension Bridge Parallel Wire Cables); FHWA; and other national, state, and pooled-fund sponsored research.
 
Task 2. Conduct a survey of suspension bridge owners and other stakeholders to collect data related to the research objectives, including feedback on NCHRP Report 534.
 
Task 3. Synthesize the literature review and survey results to identify the knowledge gaps for risk-based inspection and strength evaluation of suspension bridge main cable systems using probabilistic approaches. Discuss the quantity and quality of data required for the application of probabilistic approaches and practical limitations. These gaps should be addressed in the final product or in the recommended future research as budget permits.
 
Task 4. Propose a risk-based inspection and strength evaluation methodology, to be developed in Phase II, based on currently available data. At a minimum, the methodology shall address the following:
a)     Main cable opening frequencies, opening locations, wire sampling methodologies, and wire testing procedures;
b)     Probabilistic approaches for strength evaluation of the main cable and prediction of remaining life;
c)     Inspection and evaluation of other main cable system elements;
d)     NDE inspection techniques, SHM, and other bridge preservation advances such as dehumidification systems and effect of these on Items a, b, and c; and
e)     Inspection forms.
Task 5. Prepare Interim Report No. 1 that documents Tasks 1 through 4 as well as the data archiving plan (see Special Note C) and provides an updated work plan for the remainder of the research. This report must be submitted no later than 4 months after contract award. The updated plan must describe the process and rationale for the work proposed for Phases II though IV.
 
PHASE II—Methodology Development
 
Task 6. Develop the methodology according to the approved Interim Report No.1.
 
Task 7. Develop detailed illustrative examples to demonstrate the full range of applicability of the proposed methodology.
 
Task 8. Provide annotated outline of the proposed guidelines with a complete sample section of the proposed guidelines. This section should be publication-ready (i.e., AASHTO-style) format with appropriate level of detail.
 
Task 9. Prepare Interim Report No. 2 that documents Tasks 6 through 8 and provides an updated work plan for the remainder of the project.  This report must be submitted no later than 9 months after approval of Phase I. The updated plan must describe the process and rationale for the work proposed for Phases III and IV.
 
PHASE III—Guidelines Development
 
Task 10. Develop the proposed guidelines according to the approved Interim Report No. 2 no later than 4 months after Phase II approval.
 
Task 11. After NCHRP approval of the draft guidelines, plan and conduct a workshop with 20 representatives of suspension bridge owners and other stakeholders to review the draft proposed guidelines and implementation plan. Revise the draft proposed guidelines according to the outcomes of the workshop.
 
Note: The costs for the workshop, including invitational travel for 20 attendees, should be included in the detailed budget for the research. For the purpose of estimating these costs, assume that the workshop will be held at the Beckman Center in Irvine, CA. TRB will cover costs associated with the meeting space at the Beckman Center and NCHRP panel member travel.
 
Task 12. Prepare Interim Report No. 3 that documents Tasks 10 and 11 and provides an updated work plan for the remainder of the project. This report must be submitted no later than 9 months after Phase II approval.
 
PHASE IV—Final Products
 
Task 13. Revise the proposed guidelines and workshop materials after consideration of the panel’s review comments and prepare a ballot item for the AASHTO Committee on Bridges and Structures.
 
Task 14. Prepare final deliverables including: (a) a final report that documents the entire research effort and (b) the proposed guidelines, workshop materials, and implementation plan. These must be submitted no later than 6 months after Phase III approval.
 
STATUS: Research in progress

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