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PMSS Project Details


Project ID:FHWA-PROJ-12-0053
Project Name: Fatigue of Plasma and Laser Cut Holes
Status: Active
Last Name:Ocel
First Name:Justin
Office: Office of Infrastructure Research and Development
Team:Bridge and Foundation Engineering Team
Roadmap/Focus area(s): Infrastructure Research and Technology Strategic Plan and Roadmap
Project Description:This project will determine the fatigue strength of plates that have plasma (and possibly laser) cut holes in them. The initial matrix of specimens will be procured from three different sources that will be using different plasma-cutting machines and controlling software. The initial matrix of specimens will determine the effect on fatigue strength that the type of plasma shielding (either oxygen or air), steel type (either regular carbon or weathering grades), and the orientation of the cut termination relative to the primary stress direction may have. In addition, the hardness and cylindricality of the holes from the three different sources will be correlated to the fatigue strength to understand if it is dependent upon the machine making the cut and its controlling software. The project may also address the static strength of plasma cut holes, though this will be dependent upon procurement of a larger testing machine that has been programmed.
Laboratories: Structures Laboratory
Start Date: June 1, 2012
End Date: January 1, 2015
Goals:To determine the fatigue strength of plasma (and possibly laser) cut holes in steel plates. This fatigue strength would be compared to that of a drilled hole that is the currently accepted technique in steel bridge fabrication.
Background Information: In Article of the 2010 American Association of State Highway and Transportation Officials Load and Resistance Factor Design Bridge Construction Specifications states that bolt holes shall only be made by drilling or punching. Though a provision is provided in the commentary that "with the owner’s approval, round or slotted holes for non-main members in thin plate may successfully be thermally cut by plasma, laser, or oxygen-acetylene means." However, many owners choose not to exercise this clause because there is no data to show how these holes perform under static and fatigue loading. At the same time, current machines used in steel bridge fabrication have the ability to perform multiple fabrication processes at one time, reducing the amount of handling, thus leading to reduced fabrication costs. Until this research proves otherwise, steel bridge fabricators will have to continue performing multiple material-handling steps to accommodate standard drilling and punching operations.
Test Methodology: Full-scale experimental
Expected Benefits:Reduced steel bridge fabrication costs.
Deliverables:Name: Final research report.
Product Type(s): Research report, Data, Draft standard, specifications, or guidelines, Techbrief, Technical report
Description: A report to document all aspects of the testing, including methodology, testing matrix, results, and conclusions.
Keywords: Fatigue (Mechanics)
Steel Bridges
Metal Cutting
Fatigue Strength
Subject Areas: Bridges and other structures