Characteristics of plasma cut-welded H-shaped steel columns

H-shaped steel column members may be fabricated by welding together pre-cut flanges and the web. Fabricators are currently using plasma-cutting technique instead of traditional flame cutting. Different fabrication techniques result in different degrees of geometric imperfections and residual stresses, which can have considerable effects on the strength of steel columns. Recently an experimental investigation was conducted to establish the imperfections characteristics of plasma cut-welded H-shaped steel columns and similar flame cut-welded H-shaped steel columns. Temperature measurements were taken at certain time intervals during the cutting operations and during the welding operations. Both cutting methods had similar general variations of temperature profiles, however, recorded maximum temperatures were different. A maximum temperature of 250°C was measured immediately after welding process in each column sections. The geometric imperfection measurements were taken at closely spaced grid locations immediately after cutting, immediately after welding, and immediately after separation of the long columns into test columns. Geometric imperfections associated with plasma cut element and members were found to be less than that of the corresponding elements and members made by flame cutting. "Method of Section" technique was used to establish the built-up residual stresses in the plate, plate strip, and in the welded columns. Higher residual stress values were observed in flame cut - welded columns.