| 摘要 |
A steel joist having an upper chord, a web, and a lower chord; the upper chord consisting of an S shaped cross section elongated member having in one form a lower reverse flange at the base of the S, the flange being connected to the web so that the center of gravity of the joist is in the region of its central axis, the region between the base of the S and the reverse flange including an inclined step. |
