| 摘要 |
PCT No. PCT/IT96/00156 Sec. 371 Date Feb. 20, 1998 Sec. 102(e) Date Feb. 20, 1998 PCT Filed Aug. 1, 1996 PCT Pub. No. WO97/08400 PCT Pub. Date Mar. 6, 1997Two or more elementary sections are permanently assembled together to form continuous longitudinal slots with their longitudinal edges facing inwards and each inclined towards the opposite edge so that they converge inwardly. Fixing devices are provided and comprise a receiving matrix or plate forming a channel with walls inclined in the same way as the edges and one or more locking plugs or plates which also have lateral walls inclined in the same way as the edges. The devices may be fixed along the slots to grip the edges by a screw between matrices and plugs. The longitudinal edges of the elementary sections have corrugations corresponding to corrugations which are present in the walls of the matrices and in the lateral walls of the plugs.
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