| 摘要 |
A roll formed beam (10) of substantially rectangular cross-section formed from a unity piece of metal. The beam includes opposed first (44) and second (46) substantially parallel walls formed with at least three adjacent layers of said piece of metal (44 a, b, c, and 46 a, b, c). The beam (40) also includes opposed third (48) and fourth (5) substantially parallel walls between the first (44) and second (46) walls. One of the third (48) or fourth (50) walls has a seam (52) joining two opposed longitudinal edges of the piece of metal. A method of roll forming a beam (4) is also disclosed.
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