According to the Bolt Shear Strength Chart, the tensile strength should be around 60% of the shear strength. Contrary to popular belief, this is not a general guideline. The shear strength of a fastener is measured by its ability to withstand a load applied at a right angle to its axis before it breaks.
What Is the Shear Strength of Carbon Steel Bolts?
First, ASTM standards do not include published values or criteria for shear strength, unlike tensile and yield strengths. About 60% of the minimum tensile strength is required for shear strength, according to the Industrial Fastener Institute (Inch Fastener Standards, 7th ed. 2003, B-8).
Shear strengths of carbon steel fasteners can be expected to be around 60% of their given minimum tensile strengths as a rough empirical reference. For instance, the minimum tensile strength for an SAE grade 5 hex cap screw is 120,000 psi. Therefore, its shear strength might be 70,000 psi for design reasons."
Some imported fasteners, like lag screws, are often ungraded, and this is something you should be aware of. Due to their lack of standardized production, it is difficult to know their exact strength parameters without submitting samples for rigorous laboratory testing.
Hint: See Yield and Tensile Strength Calculation for more guidance on determining the appropriate bolt strength. When calculating the value, utilize the nominal diameter for situations where shear will occur in the unthreaded section. However, the minor diameter must be utilized if the shear region is in the threaded portion.
Geometric properties of metric bolts
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Nominal diameter - As part of the bolt identification, the nominal dimension d is included; for example, an M8 bolt has a nominal diameter of 8 millimetres. ISO 898-1 Tables 4 and 5 detail the standard metric bolt sizes. There are a variety of standard sizes for coarse pitch thread bolts, but the most common ones are M3, M3.5, M4, M5, M6, M7, M8, M10, M12, M14, M16, M18, M20, M22, M24, M27, M30, M33, M36, and M39.
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Spacing of apartments across the nut - ISO 898-2 Table A.1 specifies the hex nut width across flats s for bolt sizes M5 through M39.
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Size of the bore - Bolts used in holes with nominal clearances greater than those defined in EN 1090-2 “Requirements for the work of steel structures” will not meet the design shear resistance Fv, Rd stipulated in EN1993-1-8 Table 3.4. (4). The nominal clearance indicated in EN 1090-2 Table 11 is added to the nominal diameter d of the bolt to arrive at the final hole diameter d0 for each hole type (normal, oversize, short slotted, long slotted).
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Zone of tensile stress - The zone of maximum tension As represents the smaller cross-sectional area inside the threaded section of the bolt. The thread determines the tensile stress area, which may be determined using ISO 898-1 Chapter 9, Section 9.1.6.1. ISO 898-1 Table 4 through 7 detail the nominal stress area for both conventional coarse and fine pitch thread bolts.
Note: Tensile stress zones and shear stress zones are often distinct. The bolt’s shear strength may be determined using the tensile stress region, as shown in Table 3.4 of EN1993-1-8.
Bolt Shear Strength Chart
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As long as the shear resistance Fv, Rd of each fastener is larger than or equal to the design bearing resistance Fb, Rd, the design resistance of the group of fasteners can be considered as the total of the design bearing resistances Fb, Rd of the individual fasteners.
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Only bolt assemblies of classes 8.8 and 10.9 may be used as preloaded bolts, and the corresponding shear load Fv, Ed for slip-resistant preloaded bolted connections at the Serviceability Limit State, or Ultimate Limit State must not exceed the design slip resistance as specified in EN1993-1-8 3.9 and Table 3.2.
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Where nominal clearances do not exceed those for regular holes, as described in EN 1090-2 “Requirements for the work of steel structures,” the design shear resistance Fv, Rd may be applied. This is under EN1993-1-8 3.6.1(4).
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Table 3.3 of EN1993-1-8 specifies the minimum and maximum bolt spacing (p1, p2) and edge distances (e1, e2), respectively. Minimum values are: e1 1.2d0, e2 1.2d0, p1 2.2d0, p2 2.4d0, where d0 is the hole diameter, e1 and p1 are measured in a direction parallel to the direction of load transfer, and e2 and p2 are measured in a direction perpendicular to the direction of weight transfer.
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As long as the restrictions of e1 3.0d0, e2 1.5d0, p1 3.75d0, and p2 3.0d0 are adhered to, the bearing resistance Fb, Rd of the bolt is unaffected, as shown in EN1993-1-8 Table 3.4.
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Design shear resistance Fv, Rd should be multiplied by the reduction factor p specified in EN1993-1-8 equation 3.3 for long joints where the distance between the centres of the end fasteners measured in the direction of load transfer is more than 15d. This is under EN1993-1-8 3.6.1(12), which applies when bolts transmitting load in shear and bearing pass through packing plates of total thickness tp greater than d / 3.
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Bearing resistance Fb, Rd for bolts in non-standard holes should be increased by the following reduction factors, as shown in EN1993-1-8 Table 3.4. Excessively large holes = 0.8, and slotted holes whose longitudinal axis is perpendicular to the weight transmission direction = 0.6.
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As per EN1993-1-8, In Table 3.4, the stress resistance Ft, Rd of countersunk bolts is calculated using k2 = 0.63 rather than k2 = 0.9. Consequently, the predicted stress resistance Ft, Rd for countersunk bolts needs to be lowered by a ratio of 0.63 / 0.9 = 0.7. In addition, the bearing resistance Fb, Rd for countersunk bolts should be calculated using a plate thickness t equal to the connected plate’s depth minus half the countersinking depth.
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According to EN1993-1-8 3.6.1, resistances should be increased by a factor of 0.85 for bolts with cut threads whose threads do not conform to EN 1090. (3).
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Otherwise, according to EN1993-1-8 3.7, the design resistance of a set of fasteners shall be calculated by multiplying the total number of fasteners by the lowest value among their design resistances (1). As per EN1993-1-8 3.12, internal forces should be distributed elastically along a linear path.
Increased Bolt Shear Strength and Its Application
If bolt shear strength is to be considered, it will be incorporated into the analysis in the manner outlined for Bolt Support Force in the Theory subsection.
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When a bolt crosses a wedge’s shearing (slide) plane, the shear force will be applied. This is the case for modes D, E, and F of bolt failure.
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If a bolt crosses a dilatational plane, NO shear force will be exerted (failure modes A, B or C).
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When a shearing force is applied, it always acts perpendicular to the wedge’s sliding direction.
FAQs
1 - Do bolts have a shear strength?
The shear strength of a fastener is measured by its ability to withstand a load applied at a right angle to its axis before it breaks. Single shear describes a shearing force that acts in only one transverse plane. When a fastener is subjected to a double shear force, it is pulled in two different directions, potentially severing it into three parts.
2 - How does one determine the shear strength of an object?
You may recall the formula for calculating bending-induced shear stresses as = VQ/It. V, the shear force inside, was derived from the shear diagram. We have also determined the moment of inertia for this segment.
3 - How about tension versus shear? How about a bolt?
Both bolted joints and bolts serve primarily to transmit forces between components or secure them in place. They were also made to withstand shear forces. Thus, it is self-evident that it is more tensile than ductile.
4 - How do you calculate a bolt’s shear strength?
If the bolt is used to join two plates, and those plates are each exposed to a force (F) acting in opposing directions, then you may get the shear stress using the formula F (d x (t1+t2)).
5 - How much shear force can a 3/8 bolt take?
A good, widely-used bolt, like the Powers PowerBolt or anything similar, will not break under shear force. This type of 3/8-inch bolt can hold up to 7,000 pounds in 6,000 psi concrete (equivalent to granite) and 4,000 pounds in 2,000 psi concrete (hard sandstone).
Conclusion
When thinking about bolt shear strength, one must: In the Bolt Properties dialogue, choose the Use Shear Strength option for a property type that pertains to bolts. Shear strength requires an input value. Simply input a force value for the Shear Strength. Please be aware that the Use Bolt Orientation Efficiency option is NOT utilized in combination with the Use Shear Strength option.
If the Bolt Failure Mode is D, E, or F, and you have chosen to use the Bolt Shear Strength, then the Bolt Efficiency will not be multiplied by the shear strength. Tensile bolt capacity is calculated using the Bolt Force Diagram, and the Bolt Efficiency plays no role in this calculation. There will be no change in the shear strength of the bolts.
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