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Description
  
The scope of this cooperative agreement may include the following types of activities:
 
·         Conduct surveys of practice of bridge performance
·         Conduct data collection and analysis
·         Perform literature search and/or research studies
·         Conduct feasibility studies
·         Document demonstration projects
·         Develop specifications and criteria
·         Develop of manuals and handbooks
·         Prepare and deliver training and workshops
·         Perform analysis
·         Conduct technical review
 
A list of specific tasks were defined in the Agreement and they are shown below. These task items were intended to be broad topic areas, with the final detailed scope of work to be determined after team negotiation and with industry and other stakeholder input.
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Development of Criteria for Refined Analysis for the Purpose of Improving the Evaluation and Design of Bridges
 
Develop guidelines, protocols, and design specification criteria for bridge design and evaluation by modern, refined analytical techniques. The criteria will focus on fundamentals of Finite Element Analysis (FEA) and common applications such as steel and concrete girder bridges. 
 
At a minimum, this task will consist of the development of the following:
 
Ÿ          A comprehensive summary of FEA fundamentals for practicing bridge engineers for         proper application such as element formulation, meshing, composite section modeling,             stress   analysis, loads, and boundary conditions.
Ÿ          Protocols for refined bridge modeling, load application, and results extraction.
Ÿ          Guidelines for advanced problems such as time-dependent effects, stability, nonlinear       response, fatigue and fracture.
Ÿ          Techniques for model verification.

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Load and Resistance Factor Design (LRFD) Specifications and Manual of Refined Analysis for the Purpose of Evaluation and Design of Bridges
This task builds upon the work done in Task 1.  The primary focus of this phase is development of AASHTO LRFD specifications and comprehensive guidance.
At a minimum, this task will consist of the following:
Ÿ          Study the implications of using FEA to the safety index required by AASHTO LRFD.
Ÿ          Development of protocols for use of FEA local stresses with AASHTO LRFD.
Ÿ          Development of necessary AASHTO LRFD changes and bring to ballot.
Ÿ          Development of benchmark problems that demonstrate the accuracy of modeling
            techniques and serve as verification target and quality assurance mechanism for
            commercial software.

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Post-Tensioned Box Girder Design Manual
 
Develop a comprehensive bridge design manual on the design and construction of post-tensioned concrete box girder bridges.  The manual will cover the primary designs subject areas needed to design a post-tensioned box girder bridge superstructure.  The manual will also include a design example of a horizontally curved PT box girder bridge using the latest AASHTO LRFD Bridge Design Specification. 

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Influence of Cold Bending on Fatigue and Fracture Performance of Bridge Steels
 
Quantify the reduction of fatigue resistance and fracture toughness from cold bending in thin plate steel appropriate for use in fabrication of curved and cambered girders and modular steel bridge applications and establish rational strain and bending radius thresholds.
 
At a minimum, this task will consist of the following:
·         Material testing of small specimens with varying strain levels, aging, and temperature with focus on common bridge steels.
·          Quantify impacts to properties such as fracture toughness, fatigue resistance, tensile strength, ductility.
·         Develop recommendations for proper design and fabrication of cold-bent bridge members, including changes to relevant AASHTO specifications and disseminate information to the public.

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Orthotropic Steel Deck Rib-to-Floor Beam Connection
Develop and verify the performance of a cost-effective and durable rib-to-floorbeam connection detail that could become standard practice for new orthotropic deck construction, and is amenable to automated robotic fabrication.
 
At a minimum, this task will consist of the following:
 
      Ÿ    The design and testing of three (3) full-scale sub-assemblies of a section of an orthotropic
            deck that would include one floorbeam with a series of ribs passing through.  The
            specimen would be approximately 10ft long by 6ft wide and would be loaded in such a
            way to simulate stresses that would exist in the full 3-D deck panel.
      Ÿ    Finite element analysis of deck panel to calibrate modeling techniques and the application                         of local stress analysis for analytical fatigue design and disseminate results to the public.

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Report on Techniques for Bridge Strengthening
 
Perform a synthesis study on the various new techniques for steel and concrete bridge strengthening to restore or upgrade capacity, with objective assessment of case studies and the lessons learned.  Develop and publish a report to be used by engineers as a consultation guide when performing future design alternative studies that will build upon the National Cooperative Highway Research Program (NCHRP) Synthesis 249.  The techniques for strengthening and the lessons learned report will include, but not limited to providing options and technical guidance and examples to engineers in one consolidated document.

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Development of Inelastic Distribution Factors for Steel Girder Strength                                   Limit States
 
Perform numerical simulations to study bridge system behavior and lateral load distribution as a result of inelastic response, with the purpose of developing improved AASHTO distribution factors for design of common girder bridges.
At a minimum, task will include:
·         Conduct literature review
·         Conduct numerical simulations of bridges loaded to ultimate condition by refined 3-D FEA.
·         Conduct benchmark study to verify refined 3-D FEA modeling techniques against relevant laboratory test results from the literature.
·         Study and quantify the lateral load sharing that occurs when inelastic behavior is considered.  This will involve parametric study of a series of bridges to envelope the most common cases encountered in practice.

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System Reliability in Special Steel and Concrete Bridge Systems
Identify special steel bridge systems susceptible to reduced system reliability (series systems) or that have enhanced reliability (parallel systems), and conduct analytical reliability assessment to develop deeper understanding of relative reliability levels.
At a minimum, this task will consist of the following:
·         Calculation of System Reliability Index based on Monte-Carlo simulation or other reliability assessment technique on a series of case study bridge systems such as boxes, trusses, two-girder systems, curved girder systems.
·         Calibration of steel girder fracture limit state.           
·         Develop documentation of implications to design and rating.

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Implementation of Tubular Steel Design in Bridges
Assess the current state of national design and construction standards and specifications related to tubular steel design AASHTO, American Institute for Steel Construction (AISC), American Welding Society (AWS), American Society for Testing and Materials (ASTM), American Petroleum Institute (API). Develop recommended practice for the foresaid standards for proper use in bridges which are dynamically loaded.  Recommendations must address the material, welding, and design standards and specifications.
At a minimum, this task will consist of the following:
·         Conduct an international literature search and summarize important aspects about the design and construction specifications of at least 3 countries or industries where tubular design for dynamically loaded structures is well-established.
·         Conduct survey of existing domestic bridges that have utilized tubular design, and provide summary of important engineering data: plans, materials, specifications, inspection reports, performance, lessons learned.
·         Provide a review and assessment of the common concerns related to fatigue performance of tubular steel members and connections and how these are best addressed.
·         Develop recommended standards and specification language and work with the relevant committees from ASTM, AWS, and AASHTO to achieve implementation.

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Bridge Deck Durability Study
 
Develop durability models of bridge deck performance to gain an understanding of the influence of relevant design, construction, and environmental parameters.  Using statistical analysis of National Bridge Inspection (NBI) condition data, surveys of selected state practice, and selected simple site evaluation, develop durability models of bridge deck performance.  Work is intended to supplement ongoing, extended work as part of the Long Term Bridge Performance Program.
 
At a minimum, this task will consist of the following:
 
Ÿ  Literature review and summary of the most relevant design, construction, and environmental
    parameters that are known to affect bridge deck performance.
Ÿ  Identify key states to conduct NBI data analysis, survey of practice, and site evaluations.
Ÿ  Perform statistical analysis of NBI data and develop expected durability curves as a function
    of selected parameters.
Ÿ  Using assumed frequency distributions and failure criteria, quantify the reliability as a function
    of selected parameters.
Ÿ  Develop initial recommendations about expected deck service life as function of given
    parameters.

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Designing and Detailing Post Tensioned Bridges to accommodate Non-                         Destructive Evaluation (NDE)
 
Develop guidance design with the objective of identifying favorable combinations of post tensioning (PT) components and details and readily available NDE techniques.  This guidance will include evaluation of both internal and external post tensioning systems with emphasis on precast I-girder, precast U-girder, precast box girder, and cast in-place box girder superstructures.  This study will focus only on grouted PT systems and bridge superstructure elements.
 
At a minimum, this task will consist of the following:
 
Ÿ  Identification of promising and readily available NDE techniques.  Required inspection access
   and/or monitoring should be included in this study.
Ÿ  Comprehensive study of commonly used PT systems, components, and details. Within this
    list, identification of NDE favorable systems, components and details.
Ÿ  Comprehensive study of commonly used bridge superstructure systems, components and
    details.  Within this list, identification of NDE favorable systems, components and details.
Ÿ Guidance on favorable combination of NDE techniques, PT components/details and
   superstructure systems/details.

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Bridge Data File Protocols for Interoperability
Develop a universal bridge data file format that will promote digital exchange of engineering data between all software that may be used in the design, construction, and management of a bridge.
 
At a minimum, this task will consist of the following:
 
Ÿ The development and documentation of an organized, efficient, and robust digital file format
 that could be used to automate the exchange of data in the design, detailing, fabrication, construction, inspection, and evaluation of a bridge.
 
ŸThe placement of the data file format in the public domain that would provide all the relevant information on the bridge from the cradle to the grave.
 
ŸProvide assistance as requested to software vendors to allow for them to write “translators” to facilitate automated transfer to data.
 
ŸWork should focus on “workhorse” bridges (those with common deck superstructures as shown in AASHTO LRFD): bridge geometry, design, and fabrication data.  Develop framework for future expansion into inspection and management data.

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Research and Innovative Technology Administration (RITA) • U.S. Department of Transportation (US DOT)
1200 New Jersey Avenue, SE • Washington, DC 20590 • 800.853.1351 • E-mail RITA

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