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. The tensile stress area A s corresponds to the reduced cross-sectional area inside the threaded part of the bolt. The calculated strength properties for coarse pitch thread bolts may be used conservatively for fine pitch thread bolts. 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 resulting hole diameter d 0 for each type of hole (normal, oversize, short slotted, long slotted) is determined by adding the nominal clearance given in EN 1090-2 Table 11 to the nominal diameter d of the bolt.

Proof load is defined as the maximum tensile force that can be applied to a bolt that will not result in plastic deformation. A material must remain in its elastic region when loaded up to its proof load typically between 85-95% of the yield strength. Acceptable clamp load is typically 75% of proof load. According to EN1993-1-8 Table 3.4 the bearing resistance F b,Rd of the bolt is not affected by the spacing p 1, p 2 and edge distances e 1, e 2 provided that the following limits are observed: e 1≥ 3.0 d 0, e 2≥ 1.5 d 0, p 1≥ 3.75 d 0, p 2≥ 3.0 d 0. 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. Minimum end distance, edge distance, and spacing for bolt fasteners according to EN1993-1-8 Table 3.3 (rounded up to nearest mm) Metric class 12.9 bolts are made from quenched and tempered alloy steel and see the most use in heavy-duty applications.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 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: 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. They are often used to secure engines and drives, alongside a host of other demanding applications.

Compare the bolts you have with the diagrams below, then refer to the appropriate chart to see the ideal tightening torque. Metric Bolt Torque Chart 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: For full table with more Property Classes - rotate the screen! Metric Bolts - Fine Threads -Proof Loads ThreadThe interaction between shear and tension is expressed in EN1993-1-8 Table 3.4 according to the following linear relation: The first number of the bolt class corresponds to the ultimate strength e.g. 400 MPa for classes 4.x, 500 MPa for classes 5.x, 600 MPa for classes 6.x, 800 MPa for classes 8.x, and 1000 MPa for classes 10.x.