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      <title>Fatigue Characterization of Galvanized Welded Connections</title>
      <link>https://rip.trb.org/View/2015225</link>
      <description><![CDATA[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.]]></description>
      <pubDate>Tue, 30 Aug 2022 17:27:47 GMT</pubDate>
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      <title>Guidelines for Corrosion Protection of Steel Bridges Using Duplex Coating Systems</title>
      <link>https://rip.trb.org/View/1516169</link>
      <description><![CDATA[Bridge coatings greatly contribute to the longevity of steel bridges and reduce the total life-cycle cost by protecting steel bridge members from corrosion. For most steel bridges across the nation, the most popular practice is to provide a 3-coat, zinc-rich primer system. The 3-coat system generally requires regular maintenance (touchup), otherwise the bridge may have to be completely overcoated or the coating be removed and replaced prematurely. This approach has proven to be a maintenance challenge for bridge owners. While efforts are ongoing to improve the service life of traditional coating systems another approach would be the use of “duplex systems” (hot dip galvanized or metallized with a coating system) to provide long-term protection against corrosion. Research indicates that the synergetic life of duplex coatings will extend the bridge service life beyond the traditional coating systems. Unfortunately, bridge owners have had mixed experience with duplex coatings. Some state departments of transportation (DOTs) have had great success with the duplex coating systems while others have had issues with galvanizing and metalizing quality, experienced adhesion problems with the finish coating, or have had to perform maintenance painting of the duplex coating systems sooner than anticipated. The processes are currently reliant on the experience of the galvanizers, metalizers, and coating applicators with lack of guidelines. As a result and in order to be consistent, there is an immediate need to develop guidelines for bridge owners on the use of duplex coating systems for corrosion protection of steel bridges.

The objectives of this research were to (1) develop AASHTO guidelines for corrosion protection of using duplex coating systems for extending the service life of steel bridges that can be adopted by AASHTO and (2) plan and conduct a workshop to demonstrate the use of proposed guidelines to an audience of DOT staff and other stakeholders. The guidelines cover the selection and application of duplex coating systems during the new design, and maintenance and rehabilitation of existing steel bridges. 
]]></description>
      <pubDate>Tue, 19 Jun 2018 09:44:54 GMT</pubDate>
      <guid>https://rip.trb.org/View/1516169</guid>
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      <title>Mitigation of Weldment Cracking of Highway Steel Structures due to the Galvanizing Process</title>
      <link>https://rip.trb.org/View/1331570</link>
      <description><![CDATA[Structural supports for signs, luminaires, and traffic signals and other highway steel structures are generally galvanized to prevent corrosion and provide a long service life. However, recent investigations have revealed incidents of cracking in weldments of galvanized structures that appear to be induced during the galvanizing process. When placed in service, structures with such flaws will exhibit short service life and pose safety concerns. There was a need to identify the factors contributing to the occurrence of weldment cracking during the galvanizing process of steel highway structures and to propose improved design, materials, and construction specifications to help mitigate such cracking. This information will ensure that galvanized highway structures provide the intended service life and eliminate related safety concerns.
 
The objective of this research was to propose improved design, materials, and construction specifications of galvanized steel highway structures to mitigate weldment cracking caused by the galvanizing process. This research was concerned with structural supports for signs, luminaires, and traffic signals and bridge superstructures (other than decks).]]></description>
      <pubDate>Wed, 19 Nov 2014 01:02:44 GMT</pubDate>
      <guid>https://rip.trb.org/View/1331570</guid>
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