| Abstract |
A metal member has two edges, and a web extending between them. A plurality of recesses are formed in the web at spaced intervals. A plurality of struts extend across the web between adjacent recesses. Flange formations formed from the web around the recesses at an angle thereto so as to form the struts have a generally channel shaped cross section, and forming intermittent flanges along the web edges at the side of each recess. Also disclosed are flange formations having oblique angled or curved shapes in section, in certain regions. Also disclosed are generally three-sided indentations formed in the web at the root of each of the struts which define apices extending partially into the end of the struts. |