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Calculating Shear Strength of Grade 8 Bolts

A common question that we get here at Portland Bolt is in regards to the shear strength of bolts. The shear strength is the value at which the lateral stress on a bolt or screw causes it to fail. It is an important factor to take into consideration when designing structural steel or timber connections. Shear strength is also an easy value to roughly calculate when the ultimate tensile strength is known.

Below is a transcript of a recent live chat that we had on our website addressing shear strength. The chat was fielded by our very own Dane McKinnon and serves as a good example of what kind of response you can expect when you ask us a question. We’re substituting a generic name below for the customer to protect their privacy.

• Visitor: Henry
• Operator: Dane McKinnon
• Company: Portland Bolt
• Started: 26 Jan 2010 12:07:57
• Ended: 26 Jan 2010 12:22:18

Henry:
What is the shear strength of grade 8 bolts 1/4″ – 1″

Call accepted by Dane McKinnon. Currently in room: Dane McKinnon, Henry.

Dane McKinnon:
Good afternoon Henry. Shear strength is typically 60% of tensile strength, and the minimum tensile strength of a grade 8 bolt is 150,000 psi. We have an FAQ that addresses this question here: http://www.portlandbolt.com/faqs/bolt-shear-strength-considerations

Henry:
How are all grade 8 bolts the same tensile strength?

Dane McKinnon:
They are all the same tensile strength per square inch. The larger ones have a larger cross section of material, and so are therefore stronger. To calculate the tensile strength of a particular size, you would multiply 150,000 psi by the tensile stress area, found here: http://www.portlandbolt.com/technicalinformation/thread-pitch.html

Henry:
Thank you

Henry is now off-line and may not reply. Currently in room: Dane McKinnon.

Dane McKinnon has left the conversation. Currently in room: room is empty.

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The below content is submitted by readers and has not been researched or checked for accuracy. It is not endorsed in any way by Portland Bolt.

6 Responses to “Calculating Shear Strength of Grade 8 Bolts”

1. Ora says:

what is the shear and tension capacity of the steel anchor bolt ASTM 1554 grade 105 1.5 inches and how is it found?

thank you

2. Clayton Boaldin says:

Is there a strength requirement for 1/8″ Grade 8 Bolts? Every standard that I have seen only includes 1/4″ to 1 1/2″ sized bolts.

• Dane McKinnon says:

@Clayton – No, 1/8″ is too small to be covered under most SAE or ASTM fastener standards. The only standard I am aware of that covers small screws is ASTM A574 for socket head cap screws. In that case the tensile is 180ksi minimum and the proofload is 140ksi.