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102 Appendix d Research problem Statement AASHTO STANDING COMMITTEE ON RESEARCH AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS NCHRP Problem Statement Outline I. PRObLEM NuMbER To be assigned by NCHRP staff. II. PRObLEM TITLE Control of concrete cracking by distribution of reinforcement, including high-strength steel bars, coated and non-coated bars, and non-metallic reinforcement. III. RESEARCH PRObLEM STATEMENT Concrete is a quasi-brittle material with a low tensile strength. Applied loadings, deleterious chemical reactions, and environmental effects can result in the development of tensile stresses in concrete. When these tensile stresses exceed the concrete tensile strength, the concrete will crack. The extent and size of cracks have an effect on the performance of the bridge. However, the extent of cracking can be mini- mized by the proper distribution of reinforcement. The AASHTO LRFD Bridge Design Specifications has provisions for crack control to assure serviceability, aesthetics, and economy. Article 5.7.3.4, Con- trol of Cracking by Distribution of Reinforcement, is intended for the distribution of tension reinforce- ment to control flexural cracking. However, Equation 5.7.3.4-1 was developed to match other existing equations without any comparison with test data. There are several parameters in the equation such as bs, dc, ge, and fss that need to be investigated. There are very limited data on crack widths in specimens having typical deck slab thicknesses and containing high-strength steel bars or non-metallic reinforce- ment. There is also a question whether coated and non-coated bars should have a different maximum spacing and concrete cover. There are also two anomalies associated with the use of Equation 5.7.3.4-1. Firstly, if the concrete cover is increased to provide better corrosion protection to the reinforcement or to allow for grinding, the maximum bar spacing is required to be less. Secondly, the equation does not have to be applied to bridge decks designed by the empirical design method. This method permits a maximum bar spacing of 18 in., which is not appropriate for crack control. One of the major concerns of bridge owners is cracking in concrete bridge decks caused by shrinkage and thermal effects. Although this cracking can be reduced by proper selection of concrete constitu- ent materials, some cracking is inevitable. Specifications to control this type of cracking are needed. The proposed research is part of the following strategies of the AASHTO Technical Committee T-10 Concrete Design: Strategy 1: Keep AASHTO LRFD Concrete Design Specifications current with state-of-the-art practices. Strategy 2: Develop or modify articles in Chapter 5 that will facilitate innovative construction methods for concrete structures. Strategy 3: Identify and facilitate the advancement of state-of-the-practice through research. IV. LITERATuRE SEARCH SuMMARY NCHRP Synthesis Topic 47-01 titled âControl of Concrete Cracking in Bridgesâ includes many refer- ences related to this topic and has identified the need for this research.
103 V. RESEARCH ObjECTIVE The objectives of this research are as follows: ⢠Develop design specifications for the control of flexural cracking in concrete by distribution of reinforcement, including high-strength steel bars, coated and non-coated bars, and non- metallic reinforcement. ⢠Develop design specifications for control of shrinkage and thermal cracking in concrete bridge decks by distribution of reinforcement, including high-strength steel bars, coated and non- coated bars, and non-metallic reinforcement. In particular, the research will be focused on the following primary tasks: Task 1. Literature review summarizing the latest testing, research outcomes, and studies of control of concrete cracking by distribution of reinforcement, including high-strength steel bars, coated and non-coated bars, and non-metallic reinforcement by updating the report from NCHRP Synthesis Topic 47-01. Task 2. Investigate the current design methodologies used in the United States and elsewhere for control of concrete cracking by distribution of reinforcement for different structural components and exposure conditions. Task 3. Conduct laboratory testing of concrete specimens of different thicknesses and differ- ent concretes reinforced with high-strength steel bars, coated and non-coated bars, and non-metallic reinforcement, with different bar sizes and spacing. Task 4. Determine acceptable crack widths for durability, aesthetics, and economy. Task 5. Develop an analytical model corresponding to the results of the specimen testing program. Task 6. Recommend necessary revisions to the AASHTO LRFD Bridge Design Specifica- tions for control of cracking by distribution of reinforcement, including high-strength steel bars, coated and non-coated bars, and non-metallic reinforcement. VI. ESTIMATE OF PRObLEM FuNDING AND RESEARCH PERIOD Recommended Funding: Research Project: $490,000 Implementation activities following completion of the research: $10,000 Research Period: 36 months VII. uRGENCY AND POTENTIAL bENEFITS The final product from the research will be proposed revisions to the AASHTO LRFD Bridge Design Specifications for control of cracking in concrete structures by appropriate distribution of reinforcement. It will expand the existing articles to address design with high-strength steel bars, coated and non-coated bars, and non-metallic reinforcement. The outcome will be more logical and practical design procedures for control of concrete cracking using all types of reinforcement. Without this research, bridge designers will continue to use the existing provisions, which were not developed for all the types of reinforcement available today. VIII. IMPLEMENTATION PLANNING The final report will include the proposed revisions as a working agenda item for consideration by the AASHTO Technical Committee T-10 Concrete Design. After review, modification, and approval by Committee T-10, the proposed revisions will be submitted to the AASHTO Subcom- mittee on Bridges and Structures as an agenda item for ballot. If approved, the revisions will be incorporated into the next edition of the AASHTO LRFD Bridge Design Specifications.
104 There are no known institutional or political barriers to the implementation of the anticipated research results. IX. PERSON(S) DEVELOPING THE PRObLEM STATEMENT Henry G. Russell, PhD, S.E. Henry G. Russell, Inc. 720 Coronet Road Glenview. IL 60025 Phone: (847) 998-9137 Email: henry@hgrconcrete.com Bijan Khaleghi PhD, P.E., S.E. State Bridge Design Engineer Bridge and Structures Office Washington State DOT, P.O. Box 47340 Olympia, WA 98504-7340 Phone: (360) 705-7181 Email: khalegb@wsdot.wa.gov X. AASHTO MONITOR Bijan Khaleghi PhD, P.E., S.E. State Bridge Design Engineer Bridge and Structures Office Washington State DOT, P.O. Box 47340 Olympia, WA 98504-7340 Phone: (360) 705-7181 Email: khalegb@wsdot.wa.gov XI. SubMITTED bY Month, day, 2016, submitted by: Tom Baker, P.E. (Primary Member) State Bridge and Structures Engineer Washington State Department of Transportation P.O. Box 47340 Olympia, WA 98504-7300 Phone: (360) 705-7207 E-mail: BakerT@wsdot.wa.gov Please submit completed problem statement at: http://bit.ly/NCHRP2018Submittal Questions on the process can be directed to chedges@nas.edu.
Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACIâNA Airports Council InternationalâNorth America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing Americaâs Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TDC Transit Development Corporation TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation
A Synthesis of Highway Practice NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Control of Concrete Cracking in Bridges NCHRP SYNTHESIS 500 TRB N CHRP SYN THESIS 500 Control of Concrete Cracking in Bridges TR A N SPO R TA TIO N R ESEA R CH B O A R D 500 Fifth Street, N W W ashington, D C 20001 A D D RESS SERVIC E REQ U ESTED N O N -P R O F IT O R G . U .S . P O S TA G E PA ID C O LU M B IA , M D P E R M IT N O . 88 ANNE SPINE = .224" 030675 Concrete Cracking Final.indd 1 12/19/16 12:14 PM ISBN 978-0-309-38981-5 9 7 8 0 3 0 9 3 8 9 8 1 5 9 0 0 0 0
