Effects of Torsion and Moment on Traffic Signal Structures’ Foundations in Coastal Conditions

Existing, drilled shaft or caisson designs require large diameters rendering this design option economically unattractive, while timber piles have the drawbacks of lower load capacity (due to the structural material properties and smaller cross section diameter) and shorter service life due to durability issues within marine environments. Alternative foundation systems for traffic signal structures, such as open pipe piles, with or without torsion fins, can offer a cost-effective solution suitable for the demanding geotechnical and loading conditions of NC coastal environments, while also minimizing the footprint of the foundation to optimize right of way costs. The recommendation to investigate the feasibility of using open-ended driven steel pipe piles is based in part on the positive reviews in the recent 2015 National Cooperative Highway Research Program (NCHRP) 478 report, which indicates that this deep foundation type is becoming popular amongst many US Departments of Transportation (DOTs) as an alternative to drilled shafts or pile groups due to the high load capacity potential, cost competitiveness, and constructability, especially in coastal environments. The proposed study will conduct a comprehensive review of the national and international state of practice of foundation systems being considered for traffic and sign structures that are subject to high and complex loading demand coupled with poor foundation soil conditions. Based on this synthesis study we will select the most promising and cost-effective foundation system for detailed investigation as a possible foundation system for traffic and sign structures in coastal NC. Thus the identification of a viable, more economical foundation systems for these highway structures is the main goal of the project. A list of specific objectives proposed for this project include the following: (1) Detailed literature review and detailed survey of the state of current practice followed by other U.S. DOTs facing similar challenges e.g., high loading demand and poor foundation conditions); (2) Design and implement a detailed experimental program to be carried out under controlled conditions at the University of North Carolina (UNC), Charlotte geotechnical test pit to investigate the selected several configurations (loading, soil conditions, and geometries) of the selected foundation system; (3) Develop, validate, and calibrate 3D finite element (FE) models based on the proposed experimental program to be carried out under controlled conditions; (4) Carry out a parametric analyses using the validated and calibrated 3D FE model to assess the influence of key variables and conditions expected in NCDOT projects in the coastal region; (5) Develop design procedures, and design aids to be used by NCDOT personnel from the IT& Signal unit and the other units (e.g., unit dealing with general highway signs); and (6) Develop a comprehensive set of guidelines for the design of the selected foundation system.

Language

  • English

Project

  • Status: Active
  • Funding: $288,596
  • Contract Numbers:

    FHWA/NC/2018-17

  • Sponsor Organizations:

    North Carolina Department of Transportation

    Research and Development
    1549 Mail Service Center
    Raleigh, NC  United States  27699-1549
  • Managing Organizations:

    North Carolina Department of Transportation

    Research and Development
    1549 Mail Service Center
    Raleigh, NC  United States  27699-1549
  • Project Managers:

    Bolyard, Steven

  • Performing Organizations:

    University of North Carolina - Charlotte

    9201 University City Blvd
    Charlotte, North Carolina  United States  28223-0001
  • Principal Investigators:

    Pando, Miguel

  • Start Date: 20170801
  • Expected Completion Date: 20190731
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01640078
  • Record Type: Research project
  • Source Agency: North Carolina Department of Transportation
  • Contract Numbers: FHWA/NC/2018-17
  • Files: RiP, STATEDOT
  • Created Date: Jun 30 2017 3:39PM