Fatigue Characterization of Galvanized Welded Connections

Galvanizing is a common corrosion protection method used in highway structures, particularly for sign and lighting structures, and increasingly for bridge applications. There is some evidence of premature fatigue cracking occurring in in-service galvanized structures, and some limited studies have demonstrated lower fatigue resistance of galvanized specimens compared against non-galvanized specimens. These studies have been focused on a limited number of full-scale tests, and the issue of reduced fatigue strength of welded connections has not been studied in a systematic manner. To investigate the fatigue performance of welded connections that have been galvanized, a series of 10 welded specimens will be tested under cyclic fatigue loading. The geometry of the fatigue specimens is shown in Figure 1. The specimens will be fabricated from two plates that have been joined with a submerged arc weld (SAW) and verified to be free of defects with radiographic tests. Seven of the specimens will be galvanized before testing, and three of the specimens will be left as black steel (ungalvanized) and tested as control specimens. Galvanizing will be performed at the University of Kansas in the Learned Highbay; an active/charged galvanizing kettle is available for use in that facility for this project. All specimens to be galvanized will be dipped for a consistent amount of time (anticipated to be approximately 20 minutes) so that coatings are developed with similar thicknesses. Specimens will be prepared through degreasing and pickling or blasting before galvanizing. It is anticipated that all fatigue tests will be performed at a stress range of 20 ksi, which is greater than the constant-amplitude fatigue limit for Category B fatigue details (16 ksi). Test results between galvanized and ungalvanized specimens will be compared to characterize the sensitivity of welded connections under fatigue loading to galvanizing. Fatigue testing will be performed using the closed-loop servo-controlled Instron universal testing machine in the Lutz Fatigue & Fracture Laboratory at KU. To supplement information gained through the fatigue tests, a series of Charpy V-Notch (CVN) specimens will also be tested, as a reasonable proxy for fracture resistance. The purpose of the CVN tests will be to study the toughness of galvanized steel vs. ungalvanized steel. Three groups of CVN specimens will be considered: ungalvanized CVNs, CVNs fabricated from the steel plate and then galvanized, and CVNs fabricated from the plate after it has been galvanized. Thirty CVN specimens from each group (90 total) will be tested using an impact hammer in the Lutz Fatigue & Fracture Laboratory at the University of Kansas.

Language

• English

Project

• Status: Active
• Funding: $32042
• Contract Numbers:

  RE-0843-01

  C2180

• 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:

  Bennett, Caroline

  Collins, William

• Start Date: 20210415
• Expected Completion Date: 20231115
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Fatigue tests; Galvanizing; Highway bridges; Notch tests; Sign supports; Street lighting; Weldments
• Geographic Terms: Kansas
• Subject Areas: Bridges and other structures; Highways; Maintenance and Preservation; Materials;

Filing Info

• Accession Number: 01856891
• Record Type: Research project
• Source Agency: Kansas Department of Transportation
• Contract Numbers: RE-0843-01, C2180
• Files: RIP, STATEDOT
• Created Date: Aug 30 2022 5:27PM