| 摘要 |
<p>The invention provides a stiffened-sheet construction element. The construction element includes a primary corrugation defining a generally wave shaped profile and a secondary corrugation superimposed on the wave shaped profile. The secondary corrugation is superimposed substantially centrally or midway between a peak and a trough of the primary corrugation, thereby secondarily corrugating the primary corrugation and providing additional stiffening to the sheet.</p> |
