5. STRUCTURAL DESIGN OF CONNECTIONS The following information should be taken from the nail supplier’s DoP: • Characteristic yield moment My,k [Nmm] • Characteristic withdrawal parameter fax,k [N/mm2] • Characteristic head out-through parameter fhead,k [N/mm2] • Characteristic tensile capacity ftens,k [kN] • Nail diameter [mm] • Nail head area [mm2] • Nail length [mm] • For threaded nails also length of threaded part (lg) and length of point (lp) 5.5 SCREWED CONNECTIONS Design instructions for screwed connections are given in Eurocode 5, Section 8.7. The definitions provided in the current section introduce some differences to the Eurocode 5 instructions in order to improve the connection design of LVL. Screw suppliers also have their own design instructions for their fasteners documented in their ETAs and DoPs. These must be treated as separate supplier-specific instructions unless they make direct reference to Eurocode design. The following information should be taken from the screw supplier’s DoP: • Characteristic yield moment My,k [Nmm] • Characteristic withdrawal parameter fax,k [N/mm2] • Characteristic head out-through parameter fhead,k [N/mm2] • Characteristic tensile capacity ftens,k [kN] • Screw outer thread diameter d [mm] • Screw inner thread diameter d1 [mm] • Screw head diameter dh [mm] • Screw length L [mm] • Thread length LG [mm] 5.5.1 Laterally loaded screws in LVL The instructions specific to LVL presented in this subsection are based on the document Design rules for LVL to Eurocode 5, Proposal for discussion in CEN/TC250/SC5, Prof. Dr.-Ing. H.J. Blaβ and Dr. –Ing.M.Flaig, Blaβ & Eberhart GmbH, 30.6.2017, CEN/TC250/SC5/N0764 32 and differ partially from EN19951-1:2004. The effect of the threaded part of the screw shall be taken into account in determining the load carrying capacity by using the yield moment capacity of the screw determined in accordance with EN 14592. The outer thread diameter d shall be used to determine the embedment strength, the spacing, edge and end distances and the effective number of screws. Note: In EN 1995-1-1:2004 the embedment strength is defined based on an effective diameter def instead of the outer thread diameter d. For smooth shank screws, the yield moment capacity of the smooth shank may be used for plastic hinges occurring within the length of the smooth shank. Unless a detailed analysis is made, the yield moment capacity of the smooth shank may be used, if the smooth shank penetrates into the member containing the point of the screw by not less than 4d. Unless otherwise stated in this section, the rules for bolts apply to screws with an outer thread diameter d > 12 mm in predrilled LVL / GLVL members. The embedding strength fh,k should be taken as: f_(h,k)=(0,082 ∙ (1 - 0,01d) ρ_k)/((k_(90 )∙ sin^2 α + cos^2 α) ∙ (k_(C ) 〖∙ cos〗^2 β 〖+ sin〗^2 β) ∙ (2,5 ∙ cos^2 ε + sin^2 ε) ) (5.22) where d is the outer thread diameter of the screw [mm]; ρk is the characteristic density [kg/m³]; α is the angle between load and grain direction, see Figure 5.7; for softwood LVL-C / GLVL-C and α > 45°, α may be assumed as 45°; β is the angle between screw axis and wide face, see Figure 5.7; ε is the angle between screw axis and grain direction, see Figure 5.7; k90 is 1,15 + 0,015 d for softwood LVL / GLVL; and (5.23) k_C=max{█(d/((d-2) )@1,15) for softwood LVL┤ (5.24) Unless otherwise stated in this section, the rules for nails apply to screws with a diameter d ≤ 12 mm or screws in non-predrilled timber or LVL / GLVL members. The embedding strength should be taken as: • without predrilled holes in softwood LVL or GLVL f_(h,k)=(0,082 ∙ ρ_(k ∙)∙ d^(-0,3))/((k_C 〖 ∙ β) (5.25) • with predrilled holes in softwood LVL or GLVL f_(h,k)=(0,082 ∙ (1 - 0,01d) ρ_k)/((k_(C ) 〖 (5.26) where k_C={█(1 for LVL-P and GLVL2) )@3) for LVL-C and GLVL-C┤ )┤ (5.27) h,k = 0,082 ∙ (1 − 0,01 ) k ( 90 ∙ sin2 + cos2 ) ∙ ( C ∙ cos2 + sin2 ) ∙ (2,5 ∙ cos2 + sin2 ) N/mm2 C =max� ( −2) 1,15 for softwood LVL h,k = 0,082 ∙ k ∙∙ −0,3 ( C ∙ cos2 + sin2 ) ∙ (2,5 ∙ cos2 + sin2 ) N/mm2 h,k = 0,082 ∙ (1 − 0,01 ) k ( C ∙ cos2 + sin2 ) ∙ (2,5 ∙ cos2 + sin2 ) N/mm2 C =�1 for LVL−P and GLVL−P min� ( −2) 3 or LVL−C and GLVL−C ax,ε,Rk = ef ∙ ax ∙ ax,90,k ∙ ∙ ef β � k a�0,8 ax =�0,5+0,5∙ 45° for 15° ≤ <45° 1 for 45° ≤ ≤90° =1,5∙ cos2 +sin2 C =max� ( −2) 1,15 for softwood LVL h,k = 0,082 ∙ k ∙∙ −0,3 ( C ∙ cos2 + sin2 ) ∙ (2,5 ∙ cos2 + sin2 ) N/mm2 h,k = 0,082 ∙ (1 − 0,01 ) k ( C ∙ cos2 + sin2 ) ∙ (2,5 ∙ cos2 + sin2 ) N/mm2 C =�1 for LVL−P and GLVL−P min� ( −2) 3 or LVL−C and GLVL−C ax,ε,Rk = ef ∙ ax ∙ ax,90,k ∙ ∙ ef β � k a�0,8 made, the yield moment capacity of the smooth shank may be used, penetrates into the member containing the point of the screw by not Unless otherwise stated in this section, the rules for bolts apply to sc thread diameter d > 12 mm in predrilled LVL / GLVL members. The e should be taken as: h,k = 0,082 ∙ (1 − 0,01 ) k ( 90 ∙ sin2 + cos2 ) ∙ ( C ∙ cos2 + sin2 ) ∙ (2,5 ∙ cos2 + sin2 ) N/mm2 where d is the outer thread diameter of the screw [mm]; ρk is the characteristic density [kg/m³]; α is the angle between load and grain direction, see Figur C / GLVL-C and α > 45°, α may be assumed as 45°; β is the angle between screw axis and wide face, see Fig ε is the angle between screw axis and grain direction, se k90 is 1,15 + 0,015 for softwood LVL / GLVL; and C =max{ ( −2) 1,15 for softwood LVL Unless otherwise stated in this section, the rules for nails apply to sc 12 mm or screws in non-predrilled timber or LVL / GLVL members. T should be taken as: - without predrilled holes in softwood LVL or GLVL h,k = 0,082 ∙ k ∙ ∙ −0,3 ( C ∙ cos2 + sin2 ) ∙ (2,5 ∙ cos2 + sin2 ) N/mm2 - with predrilled holes in softwood LVL or GLVL h,k = 0,082 ∙ (1 − 0,01 ) k ( C ∙ cos2 + sin2 ) ∙ (2,5 ∙ cos2 + sin2 ) N/mm2 where C ={ 1 for LVL − P and GLVL − P min{ ( −2) 3 or LVL − C and GLVL − C 5.5.2 Axially loaded screws For connections in softwood timber or LVL/GLVL with ε ≥ 15° of scre EN 14592 with: - 6 mm ≤ d ≤ 12 mm - 0,6 ≤ d1 /d ≤ 0,75 where d is the outer thread diameter; and d1 is the inner thread diameter the characteristic withdrawal capacity should be taken as 32: LVL Handbook Europe 153
RkJQdWJsaXNoZXIy MjU0MzgwNw==