Joined in 2023 
82 
63 About this deal
M2 is the partial safety factor for the resistance of bolts in accordance with EN1993-1-8 §2.2(2) Table 2.1 and the National Annex. The recommended value in EN1993-1-8 is γ M2 = 1.25. The nominal gross area A g corresponds to the cross-sectional area of the unthreaded part of the bolt: By approximately ignoring the corner rounding for a perfect hexagon the relation of the distance across points s' and the distance across flats s is s' = s / cos(30°) = 1.1547⋅ s. The design resistance of a group of fasteners may be taken as the sum of the design bearing resistances F b,Rd of the individual fasteners provided that the shear resistance F v,Rd of each individual fastener is greater than or equal to the design bearing resistance F b,Rd. Otherwise the design resistance of a group of fasteners should be taken as the number of fasteners multiplied by the smallest design resistance of any of the individual fasteners as specified in EN1993-1-8 § 3.7(1). For this case elastic linear distribution of internal forces should be used as specified in EN1993-1-8 §3.12.
The smallest or largest pitch diameter that fits onto a screw or into a nut, including all of the form deviations such as lead, thread angle, taper, and roundness. Functional diameter is a measure of the ability to assemble the thread. According to EN1993-1-8 Table 3.4 the shear strength of the bolt may be based on the tensile stress area. v is a coefficient that takes values α v = 0.6 for bolt classes 4.6, 5.6, 8.8 or α v = 0.5 for bolt classes 4.8, 5.8, 6.8 and 10.9. When the shear plane passes through the unthreaded part of the bolt α v = 0.6.
The calculated strength properties for coarse pitch thread bolts may be used conservatively for fine pitch thread bolts. Therefore, based on the equations above, the bearing resistance of the bolt F b,Rd is not affected by the distances e 1, p 1, e 2, p 2 when the following conditions are satisfied: Minimum and maximum spacing p 1, p 2 and edge distances e 1, e 2 for bolts are given in EN1993-1-8 Table 3.3. The minimum values are: e 1≥ 1.2 d 0, e 2≥ 1.2 d 0, p 1≥ 2.2 d 0, p 2≥ 2.4 d 0, where d 0 is the diameter of the hole, e 1, p 1 are measured parallel to the load transfer direction and e 2, p 2 are measured perpendicular to the load transfer direction. For preloaded bolted connections which are slip-resistant at the Serviceability Limit State or the Ultimate Limit State the corresponding shear load F v,Ed should not exceed the design slip resistance as specified in EN1993-1-8 §3.9 and Table 3.2. Only bolt assemblies of classes 8.8 and 10.9 may be used as preloaded bolts. Pitch is the distance from the crest of one thread to the next or the distance from one thread groove to the next, measured from crest to crest. Pitch is also described as the number of threads per inch.
A is the appropriate area for shear resistance. When the shear plane passes through the threaded part of the bolt A is equal to the tensile stress area of the bolt A s. When the shear plane passes through the unthreaded part of the bolt A is equal to the gross cross-sectional area of the bolt A g. For standard coarse pitch thread and fine pitch thread bolts the nominal stress area A s is provided in ISO 898-1 Tables 4 to 7. In general the stress area of fine pitch thread bolts passing through the threaded part is larger as compared to the coarse pitch thread bolts. According to EN1993-1-8 Table 3.4 the bearing resistance F b,Rd for bolts in holes other than normal should be multiplied by the following reduction factors: Oversized holes = 0.8, slotted holes with longitudinal axis perpendicular to the load transfer direction = 0.6.
Privacy Policy
The bearing resistance of the bolt F b,Rd should be verified against the applied shear load F v,Ed in accordance with EN1993-1-8 Table 3.4: The standarized properties of metric bolts are specified in the international standard ISO 898-1:2009 'Mechanical properties of fasteners made of carbon steel and alloy steel - Part 1: Bolts, screws and studs with specified property classes - Coarse thread and fine pitch thread'.
The second number corresponds to the ratio of yield strength to ultimate strength e.g. 60% for class 4.6 leading to a yield strength of 0.60 × 400 MPa = 240 MPa.The punching resistance of the bolt B p,Rd should be verified against the applied tensile load F t,Ed in accordance with EN1993-1-8 Table 3.4: d m is the mean of the across points and across flats dimensions of the bolt head or the nut, whichever is smaller. The tensile stress area depends on the thread and it can be calculated according to ISO 898-1 Section 9.1.6.1. According to EN1993-1-8 § 3.8(1) for long joints where the distance between the centers of the end fasteners measured in the direction of load transfer is more than 15 d the design shear resistance F v,Rd of all the fasteners should be multiplied by the reduction factor β Lf specified in EN1993-1-8 equation 3.5. The yield strength f yb and the ultimate tensile strength f ub for bolt classes 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, and 10.9 are given in EN1993-1-8 Table 3.1.
Great Deal 
New Comment