Fatigue Characterization and Improvement of Cantilevered Sign Structure Box Connections

Cantilevered overhead sign structures are susceptible to fatigue issues at the connection between the pole and mast arm due to stresses caused by galloping, natural wind gusts, and truck-induced wind gusts. In some cases, box connections in the KDOT inventory have failed in fatigue. As the behavior of these box connection details are not well understood, their expected fatigue life is currently unknown. This limits KDOT’s ability to identify which structures should be considered for repair, replacement, or retrofit. Therefore, there is a clear need to characterize the expected fatigue life of the connection detail. Additionally, there may be a need to improve the fatigue performance of this connection by developing an improved connection detail and/or retrofit. To assess the fatigue performance of the cantilevered box connection, a research program including both analytical modeling and physical testing is needed. Analytical modeling is required to develop appropriate specimen geometry and loading to be used during experimental testing. Physical testing will then be performed on full-scale box connection components in the laboratory to assess their fatigue performance. Fatigue resistance will be quantified in terms of S-N curve development, identifying the appropriate fatigue classification for existing connection details. It is anticipated that between 10 and 15 fatigue tests will be performed. A final test matrix will be informed by a comprehensive literature review and the initial analytical modeling, and developed with input provided by KDOT. Additional analytical modeling will then be performed to examine parameters contributing to fatigue performance. Based on this, modifications and/or retrofits to improve fatigue resistance will be developed and examined analytically. One specific detail that will be examined is the application of an external stiffening ring.

Language

• English

Project

• Status: Active
• Funding: $155870
• Contract Numbers:

  RE-0779-01

  C2141

• Sponsor Organizations:

  Kansas Department of Transportation

  Eisenhower State Office Building
  700 SW Harrison Street
  Topeka, KS  United States  66603-3754
• Performing Organizations:

  University of Kansas Center for Research, Incorporated

  2291 Irving Hill Drive, Campus West
  Lawrence, KS  United States  66045
• Principal Investigators:

  Collins, William

  Bennett, Caroline

• Start Date: 20190601
• Expected Completion Date: 20231231
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Box beams; Cantilevers; Failure; Fatigue strength; Maintenance; Sign supports; Tests
• Geographic Terms: Kansas
• Subject Areas: Bridges and other structures; Highways; Maintenance and Preservation;

Filing Info

• Accession Number: 01856806
• Record Type: Research project
• Source Agency: Kansas Department of Transportation
• Contract Numbers: RE-0779-01, C2141
• Files: RIP, STATEDOT
• Created Date: Aug 30 2022 3:55PM