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The National Academies

NCHRP 12-119 [Active]

MASH Railing Load Requirements for Bridge Deck Overhang

  Project Data
Funds: $440,000
Staff Responsibility: Dr. Waseem Dekelbab
Research Agency: University of Nebraska - Lincoln
Principal Investigator: Dr. Joshua Steelman
Effective Date: 8/17/2020
Completion Date: 8/17/2023

BACKGROUND
 
State highway agencies across the country are upgrading standards, policies, and processes to satisfy the 2016 AASHTO/FHWA Joint Implementation Agreement for the AASHTO Manual for Assessing Safety Hardware (MASH). The AASHTO loading requirements for design of the bridge deck overhang is based on NCHRP Report 350. In order to meet the MASH implementation agreement, the loading requirements and analysis method of bridge deck overhang should be investigated, and the AASHTO LRFD Bridge Design Specifications should be modified accordingly. The research is of urgent need to ensure public safety and satisfy the AASHTO MASH and LRFD bridge design requirements.
 
OBJECTIVES
 
The objectives of this research are to (1) propose modification to the AASHTO LRFD Bridge Design Specifications related to loading requirements of the AASHTO MASH for bridge deck overhang and (2) develop examples to demonstrate the application of the proposed modifications. At the minimum, the research shall include the analysis and design of bridge deck overhang for concrete, metal, solid and post-beam railings (including curbed and non-curbed) subjected to each of the MASH collision loads.
 
Accomplishment of the project objectives will require at least the following tasks.
 
TASKS
 
Task descriptions are intended to provide a framework for conducting the research. The NCHRP is seeking the insights of proposers on how best to achieve the research objectives. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers' current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the research objectives.
 
PHASE I—Planning
 
Task 1.Conduct a literature review of relevant research considered to be the state-of-the-practice in testing, evaluating, and designing of bridge deck overhang railings. The review shall include published and unpublished research conducted through the NCHRP; FHWA; and other national, international, state, and pooled-fund sponsored research.
 
Task 2. Synthesize the literature review to identify the knowledge gaps for the design of bridge deck overhang. These gaps should be addressed in the proposed modifications or in the recommended future research as budget permits.
 
Task 3. Propose analytical and testing programs, to be executed in Phases II and III, to achieve the project objectives. The analytical program shall include the loading requirements and analysis methods for each of the MASH collision loads. The testing program shall include dynamic impact testing to validate the analytical program.
 
Task 4. Identify areas of the current AASHTO LRFD Bridge Design Specifications that will be modified.
 
Task 5. Prepare Interim Report No. 1 that documents Tasks 1 through 4 and provides an updated work plan for the remainder of the research. This report must be submitted no later than 4 months after contract execution. The updated plan must describe the process and rationale for the work proposed for Phases II though IV.
 
Note: Following a 1-month review of Interim Report No. 1 by the NCHRP, the research team will be required to meet in person with the NCHRP project panel to discuss the interim report. Work on Phases II though IV of the project will not begin until authorized by the NCHRP. Phase I shall be limited to $40,000.
 
PHASE II—Analytical Program
 
Task 6. Execute the analytical program according to the approved Interim Report No.1.
 
Task 7. Finalize the testing program work plan. Describe how the testing results will be utilized to achieve the research objectives.
 
Task 8. Provide a matrix of the examples to demonstrate the application of the proposed modifications.
 
Task 9. Prepare Interim Report No. 2 that documents the results of Tasks 6 through 8 and provides an updated work plan for the remainder of the project. This report is due no later than 8 months after approval of Phase I. The updated plan must describe the work proposed for Phases III and IV.
 
Note: Following a 1-month review of Interim Report No. 2 by the NCHRP, the research team will be required to meet in person with the NCHRP project panel to discuss the interim report, if necessary. Work on Phases III and IV of the project will not begin until authorized by the NCHRP. Phase II shall be limited to $150,000.
 
PHASE III—Testing Program
 
Task 10. Execute the testing program according to the approved Interim Report No. 2.
 
Task 11. Validate the analytical program based on the testing results and update accordingly.
 
Task 12. Develop the examples to demonstrate the application of the proposed modifications.
 
Task 13. Prepare Interim Report No. 3 that documents the results of Tasks 10 through 12 no later than 9 months after approval of Phase II. The updated plan must describe the work proposed for Phase IV.
 
Note: Following a 1-month review of Interim Report No. 3 by the NCHRP, the research team will be required to meet in person with the NCHRP project panel to discuss the interim report, if necessary. Work on Phase IV of the project will not begin until authorized by the NCHRP.
 
PHASE IV—Final Products
 
Task 14. Develop the draft proposed AASHTO modifications based on the research results. The draft proposed AASHTO modifications are due no later than 2 months after approval of Phase III.
 
Task 15. Prepare final deliverables including: (1) the proposed AASHTO modifications that reflect consideration of the panel’s review comments, (2) examples demonstrating the application of the proposed modifications, (3) a final report that documents the entire research effort, and (4) a stand-alone technical memorandum titled “Implementation of Research Findings and Products.” See Special Note D for additional information.
 
Note: Following receipt of the draft final report, the remaining 3 months shall be for NCHRP review and comment and for research agency preparation of the revised final report. Phase III and IV shall be limited to $250,000.

STATUS:
Research in progress

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