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    strength of threaded rod?

    An electrical question although I'm not using it for electrical purposes.

    What is the shear strength of standard galv threaded rod 5/8"?
    Searching the web results in a wide range of answers.

    ​​​​​​Shear strength is said to be 60% of tensile strength.

    Is there a reference that you trust?

    ​​​​​​In other words, If a 5/8 threaded rod is inserted into a wall, how much downward force can it bear (close to wall) before shearing off?
    John,

    #2
    I think other factors are relevant, like the grade of the steel, stainless or carbon. If you know the manufacturer of the rod you are considering, I'd contact them for the information you seek.

    If you trust "Red Head", then, http://www.itwredhead.ca/admin/pdf/2...nce-Tables.pdf

    Comment


      #3
      190910-0638 EDT

      I did not do any great amount of checking, and did not look at an old textbook. But you can expect a lot of different answers. One major factor is what is the assumed safety factor.

      The kind of steel, processing, and heat treatment are major factors, and where it was made.

      One interesting site is http://www.barnhillbolt.com/specs/Ep...wShearPerf.htm . But the site does not directly specify assumptions. It does compare 1018, ordinary low carbon CRS, 4140 a very good heat treatable alloy, and stainless.

      If you assume 50,000 PSI for tensile strength, 0.3 sq-in reduced by some factor to get minor diameter, possibly 0.2 sq-in, then tensile is about 10,000 #. So 3000 # from the above site may not be too bad of a figure.

      Just for comparison the tensile loading on a typical automotive pinion is about 25,000 to 35,000 #. These run with nil failure rate under some sever conditions.

      .

      Comment


        #4
        Temporary bracing in wood frame construction - what fasteners should one trust more, especially something that is to hold while you are working on the structure?

        With lateral forces softer metal nails bend, but generally don't break. Hardened screws break quite often. But the screws are stronger when it comes to linear forces, plus engaged threads help hold more.

        There is give and take here depending on what the goals are and composition of metal and heat treatments change those results.
        I live for today, I'm just a day behind.

        Comment


          #5
          Standard threaded rod is not very strong. Probably roughly equivalent to a grade 2 bolt, ~ 60KSI. You can get higher grades from a place like mcmaster carr. I remember looking into this in the past, and my recollection is that for steels you can figure shear strength is about 50% of tensile strength which isnt too far off from your figure. There is this thing called "maximum shear theory" that says that I think.
          Ethan Brush - East West Electric. NY, WA. MA

          "You can't generalize"

          Comment


            #6
            https://interestingengineering.com/u...lkway-collapse
            [COLOR=#000000]The reports of my death are greatly exaggerated.[/COLOR]

            Comment


              #7
              Thanks for your advice but much of this confuses me.
              Lets assume worst case and its soft crs threaded rod.
              Barnhillbolt says tensile 2940 which is about 1500 shear?
              Then, itwreadhead say 5870 tensile.
              Why twice as much?
              John,

              Comment


                #8
                Originally posted by S'mise View Post
                Thanks for your advice but much of this confuses me.
                Lets assume worst case and its soft crs threaded rod.
                Barnhillbolt says tensile 2940 which is about 1500 shear?
                Then, itwreadhead say 5870 tensile.
                Why twice as much?
                Those red heads could be a higher grade steel. High grade steel is three times as strong as low grade. Grade 2 bolt is 60ksi, grade 8 is 150ksi - huge difference.
                Ethan Brush - East West Electric. NY, WA. MA

                "You can't generalize"

                Comment


                  #9
                  Originally posted by S'mise View Post
                  Thanks for your advice but much of this confuses me.
                  Lets assume worst case and its soft crs threaded rod.
                  Barnhillbolt says tensile 2940 which is about 1500 shear?
                  Then, itwreadhead say 5870 tensile.
                  Why twice as much?
                  Barnhillbolt is allowable shear loads and itwreadhead is Average Ultimate Tension and Shear Loads, note 1 says the static loading should not exceed 25% capacity or the allowable load of the anchor rod. 5870 * .25 = 1,468.

                  Comment


                    #10
                    I don't know what you are engineering, but you might be surprised at how reasonable a 30 minute sit down with a structural engineer can be. It's worth making a phone call if people are involved or could get hurt from what you are doing.

                    Then again, maybe I'm just paranoid.

                    Comment


                      #11
                      Originally posted by electrofelon View Post
                      Those red heads could be a higher grade steel. High grade steel is three times as strong as low grade. Grade 2 bolt is 60ksi, grade 8 is 150ksi - huge difference.
                      Both should be the same under column SAE1018/A307.
                      To Kwired's point, isn't it better for bending of softer metals as opposed to a harder grade/strength that would be more likely to snap off?

                      For instance stainless steel is very hard but breaks much easier than softener steel.
                      John,

                      Comment


                        #12
                        Originally posted by oldsparky52 View Post

                        Barnhillbolt is allowable shear loads and itwreadhead is Average Ultimate Tension and Shear Loads, note 1 says the static loading should not exceed 25% capacity or the allowable load of the anchor rod. 5870 * .25 = 1,468.
                        Thanks, good to know.
                        John,

                        Comment


                          #13
                          Originally posted by S'mise View Post
                          Both should be the same under column SAE1018/A307.
                          To Kwired's point, isn't it better for bending of softer metals as opposed to a harder grade/strength that would be more likely to snap off?

                          For instance stainless steel is very hard but breaks much easier than softener steel.
                          There is a common myth that, say, a grade 5 bolt is better than a grade 8 bolt because grades 8's are brittle. This is not true. A grade 5 will have exceeded yield and failed before the grade 8 even enters the plastic region.

                          Another thing to to consider about bolted joints is that bolts generally do not see much shear due to the tremendous friction between the shearing parts.

                          Ethan Brush - East West Electric. NY, WA. MA

                          "You can't generalize"

                          Comment


                            #14
                            Originally posted by electrofelon View Post
                            Another thing to to consider about bolted joints is that bolts generally do not see much shear due to the tremendous friction between the shearing parts.
                            This is correct. When you see the large splices in steel beams holding up interstate overpasses, it's the friction between the splice plates and the beams that provides the strength of the joints, which comes from the bolts' tensile strength, not shear strength.
                            Master Electrician
                            Electrical Contractor
                            Richmond, VA

                            Comment


                              #15
                              Originally posted by electrofelon View Post

                              There is a common myth that, say, a grade 5 bolt is better than a grade 8 bolt because grades 8's are brittle. This is not true. A grade 5 will have exceeded yield and failed before the grade 8 even enters the plastic region.

                              Another thing to to consider about bolted joints is that bolts generally do not see much shear due to the tremendous friction between the shearing parts.
                              That's a greateat point. Can I assume threaded rod shear is essentially the same? That is, the weak point in either being the narrowest part of the thread?

                              Is tensile strength higher in a bolt since the head of a bolt would be stronger than a nut?
                              John,

                              Comment

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