| 摘要 |
In the structure, each post beam 4 or crosspiece beam 5 consists of a box having a rectangular cross-section, the large side of which is parallel to the plane of the portal, the small faces of the beams having a constant width and their large faces having the ordinary trapezoidal appearance of portal beams. Each beam may be formed of two parts having a U-shaped cross-section 6, 7 in which the base of the U forms a large face of the beam and the arms of the U each form half of a small face of the beam. The two parts having a U-shaped cross-section 6, 7 are joined together by welding 8, 9 their corresponding edges. <IMAGE>
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