2. LVL STRUCTURES IN FLOORS, WALLS, ROOFS AND IN SPECIAL APPLICATIONS 2.3.6 Bracing panels Bracing is needed to transfer horizontal loads, like wind loads, from the building frame to the foundations. When panel bracing is used, additional diagonals or other bracing systems are usually not necessary and the structure becomes simpler. LVL-C panels are ideal for bracing in various types of buildings as they are easy to fasten to most materials and LVL-C panels are available in large sizes. Frame spacing can be large without risk of bracing panel buckling. Horizontal bracing panels transfer horizontal loads to the vertical wall bracing panels which, in turn, transfer the forces downwards. If the edges of the panels are not fully supported, the resistance against lateral torsional buckling of the compressed edge must be verified as a beam. Fastening the panels to the frame structures is essential for the capacity of the bracing. Preliminary design values for panel fastenings are presented in Section 5.7. In roofs and walls of conventional buildings, LVL-C panels can also be utilized as a water vapour and air barrier on the interior side of the structure, so no separate barrier layer is needed. The fire behaviour of LVL-C is highly predictable, which makes it a suitable bracing panel also with respect to fire design 24. 2.3.7 Large LVL I-beams and box beams LVL can be used for the main beams of roof structures in large buildings when they are structurally glued to larger I-beams or box beams. The advantage of these LVL beams is that they are not sensitive to cracking in dry or changing moisture conditions. The beam heights can also be tailored project-specifically. The beams have LVL-C webs and LVL-P flange components. Recommended beam heights are 900, 1200, 1800 or 2500 mm. I-joists have the best material efficiency, but if the fire resistance requirement is higher than R15, box beams are required. Figure 2.52. Panel bracing of roof structure. Figure 2.53. Large LVL I-beams and box beams for main beams of roofs. 82 LVL Handbook Europe
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