6. PERFORMANCE OF LVL IN FIRE Figure 6.9. Effective cross section after 30 min fire exposure Table 6.2. Effective thickness of LVL 36 C panels after 15 - 60 min fire exposure on one side. Table 6.3. Minimum thickness of LVL 36 C panel to give a fire exposure protection time 30 - 90 minutes for an underlying wooden structure. LVL 06, Table 6.2 LVL-C panel Original thickness [mm] Effective thickness after 15 min [mm] Effective thickness after 30 min [mm] Effective thickness after 60 min [mm] 27 12 - - 33 18 - - 39 24 12 - 45 30 18 - 51 36 24 - 57 42 30 11 63 48 36 17 69 54 42 23 75 60 48 29 LVL 06, Table 6.3 Resistance to fire requirement R [min] Minimum thickness hp1 of LVL 36 C panel protecting timber frame assemblies [mm] Minimum thickness hp2 of LVL 36 C panel protection applied directly on beams or columns [mm] 30 29 27 45 39 36 60 49 46 75 58 56 90 68 66 Example: 133x400 mm GLVL-P beam in 30 minutes fire exposure on all sides: d_ef=β_n∙t+k_0∙d_0=0,70 mm/min∙30min+1,0∙7mm=28mm Size of the effective cross section: Width b: 133 mm - 2∙28 mm = 77 mm Height h: 400 mm - 2∙28 mm = 344 mm Design value of bending strength for LVL-48 P: f_(m,d,fi)=k_(mod,fi)∙(k_fi∙〖k_h∙f〗_(m,k))/γ_(M,fi) =1,0∙(1,1∙(300mm/344mm)^0,15∙44 N/mm^2 )/1,0=47,4 N/ mm^2 When LVL-C panels are exposed to fire on one side, the one-dimensional charring rate β0 is used for calculation of the effective panel thicknesses. Table 6.2 shows the thicknesses after 15, 30 and 60min fire exposure. It is recommended that the effective thickness has at least one cross veneer. The values are thus shown for cases where the effective thickness is at least 9 mm. ef = n ∙ + 0 ∙ 0 = 0,70 mmmin∙ 30min+1,0∙ 7mm=28mm m,d,fi = mod,fi ∙ fi ∙ h ∙ m,k M,fi =1,0∙ 1,1∙ � 33 04 04 mm mm�0,15 ∙ 44 m Nm2 1,0 =47,4 m N m2 ef = n ∙ + 0 ∙ 0 = 0,70 mmmin∙ 30min+1,0∙ 7mm=28mm m,d,fi = mod,fi ∙ fi ∙ h ∙ m,k M,fi =1,0∙ 1,1∙ � 33 04 04 mm mm�0,15 ∙ 44 m Nm2 1,0 =47,4 m N m2 164 LVL Handbook Europe
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