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3 C H A P T E R 1 Introduction The objective of this research was to develop new specifi- cations for structural supports for luminaires, traffic signals, and signs (LTS). The resulting specifications are arranged in three divisions: ⢠Design, based on the load and resistance factor design (LRFD) methodology, ⢠Construction (e.g., material specifications, fabrication, installation), and ⢠Asset management (e.g., inventory, inspection, maintenance). The research goal was to provide AASHTO the basis for forming a new edition of the AASHTO Standard Specifica- tions for Structural Supports for Highway Signs, Luminaires, and Traffic Signals along with the necessary report that out- lines reliability calibration and example problems. Herein the term LRFD-LTS specifications or LRFD specifications refers to the LRFD draft specifications developed as part of this project. Other AASHTO specifications titles are used with appropriate qualifiers (e.g., STD-LTS or standard LTS specifications). Organization This project was divided into five phases that progressed sequentially. This final report is organized to document the deliverables listed in Table 1. The draft specifications are written in the AASHTO LRFD format and are ready for implementation after review, modification, and possible adoption by the Subcommittee for Bridges and Structures (SCOBS), and finally, approval by AASHTO. The Calibration Report in Appendix A documents many of the studies that were necessary to determine the load and resistance factors. It also addresses the simplification associated with ice loads. The example problems are contained in Appendix C (avail- able on the TRB website by searching for NCHRP Report 796 at www.TRB.org); these will facilitate implementation and technology transfer. This report will bring forward the highlights of the work for the purpose of a general overview. The reader is encouraged to review the LRFD specifications (a separate AASHTO publica- tion), the example problems (Appendix C), and the Calibra- tion Report (Appendix A). Contents of the LRFD-LTS Specifications The LRFD-LTS specifications are organized in a similar manner to the STD-LTS for Division IâDesign. There was serious consideration given to splitting Section 11: Fatigue Design, which contains both loads and resistance informa- tion, and placing this content in Section 3: Loads, Section 5: Steel Design, and Section 6: Aluminum Design. On discus- sion with the project team and panel, the decision was made to keep the fatigue information in the present section without splitting. Division II: Fabrication and Construction contains two new sections for the LRFD-LTS specifications. Here, infor- mation associated with these topics available in the STD-LTS was extracted from the design sections and organized in Divi- sion II. Additional information was added based on research, observed problems in the field, and best practices. Division III: Asset Management contains new information developed in this project as well as best practices regarding Section 16: Inspection and Reporting and Section 17: Asset Management. All divisions are written for maintainability and expansion as research and practice guide the AASHTO LTS community and AASHTO T-12. Introduction and Research Approach
4The contents of the LRFD-LTS specifications are as follows. Division I: Design Section 1: Introduction Section 2: General Features of Design Section 3: Loads Section 4: Analysis and DesignâGeneral Considerations Section 5: Steel Design Section 6: Aluminum Design Section 7: Prestressed Concrete Design Section 8: Fiber-Reinforced Composite Design Section 9: Wood Design Section 10: Serviceability Requirements Section 11: Fatigue Design Phase Description Detailed Description Deliverable I Develop detailed outline for stand- alone specifications The standard specifications will be converted to the LRFD approach and reorganized to provide design engineers with state-of-the-art specifications separating the design, construction, and asset management into three distinct divisions. Typical initial activities were conducted, including: a. Review of literature, b. Review of international specifications, c. Survey of AASHTO agencies, d. Development of detailed outline, and e. Recommend approach for developing the LRFD specifications. II Develop LRFD design specifications division Based on the approved work plan, develop the proposed design specifications. Prepare detailed design examples that fully illustrate the application of the new design methods. The LRFD specifications (Division I) were written, calibrated, and documented with commentary and example problems. Three primary documents support this report: a. Calibration Report (Appendix A), b. LRFD Specifications (AASHTO document), and c. Example Problems (Appendix C). III Develop construction specifications division Develop a construction division by extracting the current construction provisions from existing AASHTO specifications and incorporating updated material specifications, fabrication methods, and installation techniques supplemented by state-of-the-art practices. The LRFD specifications (Division II) were written and organized into two new sections: a. Fabrication, Materials, and Detailing; and b. Construction. These sections are contained in the LRFD specifications. IV Develop asset management division specifications Develop language outlining best practices for inventory, inspection, and maintenance. Additionally, develop metadata for inventory and commonly recognized element levels. The LRFD specifications (Division III) were written and organized into two new sections: a. Inspection, and b. Asset Management. V Deliverables Prepare and submit project deliverables, including a final report that documents the entire research effort and other items identified in the research plan. This report and its appendices provide the final deliverables. There are four major documents: a. The Final Report (this report), b. Calibration Report (appendix), c. Draft LRFD Specifications (AASHTO), and d. Example Problems (appendix). Table 1. Project overview. Section 12: Breakaway Supports Section 13: Foundation Design Division II: Fabrication and Construction Section 14: Fabrication, Materials, and Detailing Section 15: Construction Division III: Asset Management Section 16: Inspection and Reporting Section 17: Asset Management Appendices Appendix A: Analysis of Span-Wire Structures Appendix B: Design Aids Appendix C: Alternative Fatigue Analysis/Evaluation Appendix D: Detailed Element Descriptions
