Evaluation of Bolt Holes Fabricated by Using Plasma Arc Cutting

Abstract

Modern technologies for plasma cutting have the potential to produce bolt holes that perform on a par with those made by currently accepted methods and at the same time to reduce fabrication costs related to steel bridge construction. Current specifications do not allow holes in primary members to be formed by using plasma cutting. A lack of data showing how plasma-cut holes perform under fatigue and tensile loading inhibits their use in secondary members as well. This paper presents findings from an ongoing investigation into the structural performance of steel members with plasma-cut bolt holes. Specimens include members with a single plasma-cut hole and connection members. Material with plasma-cut holes was procured from four fabricators throughout various industries. Results from approximately 170 fatigue tests and 34 tensile tests are presented. Data from the fatigue tests show that under certain conditions, plasma-cut bolt holes perform comparably to drilled and punched holes. Results from tensile testing are mixed, with 29 of 34 tests exhibiting brittle failure, and most test specimens exceeding the tensile strength of the material. Geometric properties of the plasma-cut holes were measured as well and did not meet current specifications.