| 摘要 |
A tubular structural member has substantially constant cross-sectional size and configuration along its length between its opposite ends. The member has a pair of parallel oppositely aligned flat areas in its exterior surface. The member has substantially uniform wall thickness except in a selected portion of each the opposing areas where the member's wall thickness is a selected amount greater than the uniform wall thickness. The increase wall thickness preferably is manifested in the interior of the tubular member. The cross-sectional area of the member can have orthogonal neutral axes, and the exterior dimension of the member along one of those axes can be greater than the exterior dimension of the member along the other of those axes which is normal to the exterior flat areas; the amount and distribution of the thickening of the member's walls over the uniform thickness can be defined to cause the section modular of the member about each of the neutral axes to be substantially equal. |
