4.3.12 Holes Eurocode 5 does not provide instructions for designing holes in beams, but such instructions are presented in the non-conflicting complementary instructions (NCCI) for Eurocode 5. The design method presented in this subsection is based on the Austrian NCCI document ÖNORM B 1995-1-1:2015, annex F 33 and it can it be applied to holes in LVL beams in service class 1 and 2 conditions. LVL suppliers have in their technical documentation also their own tailored instructions for designing holes in LVL beams with different boundary conditions. For all beams with holes the bending, shear and tension/ compression resistance shall be verified at the location of the hole. When the diameter d of the hole is ≥ 50 mm or ≥ h/10, the resistance against tension perpendicular to the grain shall be verified by equation (4.57), shear stress concentration shall be verified by equation (4.62). The bending stress at the location of the hole shall be verified by equations (4.64) and (4.65) for rectangular holes or (4.71) for round holes. The corners of rectangular holes shall be a rounding radius r ≥ 15 mm. The boundary conditions of the geometry are specified in Figure 4.25. The verification of the resistance against tension perpendicular to the grain stresses can be the most critical condition to fulfil in the design of holes in LVL-P beams. LVL-C beams, on the other hand, offer a significant advantage for beams with holes, as the cross veneers act as reinforcement around the holes preventing cracking due to tension stresses perpendicular to the grain. Their resistance is therefore superior and the larger hole size limit for reinforced holes specified in the Austrian NCCI document may be applied to LVL-C beams. Tension stress perpendicular to the grain in verified by the equation σ_(t,90,d)=F_(t,90,d)/(0,5 (4.57) where k_(t,90)=min{█(1@(450/h)^0,5 )┤ (4.58) σt,90,d is the design value of tension stress perpendicular to the grain [N/mm2]; Ft,90,d is the design value of tension force perpendicular to the grain [N]; lt,90 is the load distribution length [mm], see Figure 4.26; b is the beam thickness [mm]; ft,90,d is the design value of tension strength perpendicular to the grain [N/mm2]; and h is the beam height [mm]. The tension perpendicular to the grain force Ft,90,d depends on the shear force Vd and bending moment Md at the edge of the hole: F_(t,90,d)=(V_d∙h_d)/(4∙h)∙[3 (4.59) where h_r={█(min(h_ro;h_ru ) for rectang (4.60) t,90,d = t,90,d 0,5 ∙ t,90 ∙ ∙ t,90 ≤ t,90,d t,90 = � 1 �4 ℎ 50�0,5 t,90,d = d∙ℎd 4∙ℎ ∙ �3−�ℎdℎ �2� +0,008∙ dℎr ℎr =� min(ℎro; ℎru) for rectangular holes min(ℎro +0,15∙ ; ℎro +0,15∙ ) for round holes t,90 = �0,5∙ (ℎd +ℎ) for rectangular holes 0,35∙ +0,5∙ ℎ for round holes d = τ ∙ 1,5 ∙ d ∙ (ℎ−ℎd) ≤ v,d τ =1,85∙ �1+ ℎ� ∙ �ℎdℎ �0,2 t,90,d = d∙ℎd 4∙ℎ ∙ �3−�ℎdℎ �2� +0,008∙ dℎr ℎr =� min(ℎro; ℎru) for rectangular holes min(ℎro +0,15∙ ; ℎ +0,15∙ ) for round holes t,90 = �0,5∙ (ℎd +ℎ) for rectangular holes 0,35∙ +0,5∙ ℎ for round holes d = τ ∙ 1,5 ∙ d ∙ (ℎ−ℎd) ≤ v,d τ =1,85∙ �1+ ℎ� ∙ �ℎdℎ �0,2 ru 4. STRUCTURAL DESIGN OF LVL STRUCTURES Figure 4.25. Geometrical boundary conditions of holes in beams 33. LVL 04, Figure 4.25 Product type lv lA lz hro and hru a hd LVL-P ≥ h ≥ 0,5 h Max (≥1,5h; 300 mm) ≥ 0,35 h ≤ 2,5 hd ≤ 0,15 h LVL-C ≥ h ≥ 0,5 h Max (≥1,5h; 300 mm) ≥ 0,25 h ≤ 2,5 hd ≤ 0,4 h Product type lv lA lz hro and hru LVL-P ≥ h ≥0,5h Max(≥1,5h; 300 mm) ≥0,35h ≤2 LVL-C ≥ h ≥0,5h Max(≥1,5h; 300 mm) ≥0,25h ≤2 Figure 4.25. Geometrical boundary conditions of holes in beams 33 (Kuva_ beams) Tension stress perpendicular to the grain in verified by the equation t,90,d = t,90,d 0,5 ∙ t,90 ∙ ∙ t,90 ≤ t,90,d (4.57) where t,90 = {( 1 4 ℎ 50)0,5 t,90,d is the design value of tension stress perpendicular to the gra is the design value of tension force perpendicular to the grai t,90 is the load distribution length [mm], see Figure 4.26; b is the beam thickness [mm]; t,90,d is the design value of tension strength perpendicular to the g 134 LVL Handbook Europe
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