Out-of-plane Eccentric load on bolted group
Out-of-plane Eccentric load on bolted group
(OP)
Hi peeps,
This frame will be bolted on the ground. The load applied is shown by the red arrow, my question is how to deal with this loading type. Can anyone recommend an analysis method for the bolts ? I know the bolts are undergoing shear force and bending moment (out-of plane), but I'm not familiar with real life approaches to this problem (Steel code etc.).
Attached are some views to this structure


This frame will be bolted on the ground. The load applied is shown by the red arrow, my question is how to deal with this loading type. Can anyone recommend an analysis method for the bolts ? I know the bolts are undergoing shear force and bending moment (out-of plane), but I'm not familiar with real life approaches to this problem (Steel code etc.).
Attached are some views to this structure








RE: Out-of-plane Eccentric load on bolted group
Bolts a good for shear and tension...but not bending
Then you should go see an structural engineer near you :)
best regards
Klaus
RE: Out-of-plane Eccentric load on bolted group
http://publications.lib.chalmers.se/records/fullte...
RE: Out-of-plane Eccentric load on bolted group
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Out-of-plane Eccentric load on bolted group
RE: Out-of-plane Eccentric load on bolted group
and the shear reactions should be pointed left, not right.
I was in a hurry!
RE: Out-of-plane Eccentric load on bolted group
Thanks for your help and thanks to all for the feedback and replies.
RE: Out-of-plane Eccentric load on bolted group
I'm not sure whether you are familiar with concrete code procedures for checking capacities of bolts embedded in concrete (I've been presuming concrete base when you mentioned "ground", but please let me know if I'm mistaken). The relevant code is ACI 318-14, there are some long, convoluted equations for determining capacity, checking a few different failure modes. There are some simple software programs that aid this. But the upshot is that in these scenarios, the potential breakout of anchor bolts from the concrete almost always governs over the actual capacity of the bolt steel.
RE: Out-of-plane Eccentric load on bolted group
The load, call it "P", acts above the surface at an eccentricity, "e", parallel to the plane of the surface. This creates a moment equal to P*e.
The shear is resisted by the bolts by sharing the load equally among them. So you divide P by the number of bolts to determine the shear in any bolt.
The moment is resisted by tension in the front bolts and compression in the back bolts. Typically the back bolts don't transfer the compression, the frame bearing against the surface does the work. For the front bolts, they are in tension. The resisting lever arm is the distance "d". So you divide the moment, Pe, by "d" to get the tension in the bolts. Then you divide that by the number of bolts in the front since you assume they share that tension load equally.
Once you find the tension and shear in those front bolts, you compare that to the capacity of whatever bolts you choose to use. Let's say:
the shear reaction is 2000 lb. and the tension reaction is 1000 lb.
the shear capacity of your selected bolt is 3000 lb. and the tension capacity is 2000 lb.
In shear, the demand/capacity ratio is 2000/3000 = 67%
In tension, the demand/capacity ratio is 1000/2000 = 50%
Adding these together gets you 67% + 50% = 117%
The bolts are over capacity and you must use a different bolt.
RE: Out-of-plane Eccentric load on bolted group
For calculation purposes I am referencing the link posted on this thread (http://publications.lib.chalmers.se/records/fullte...).
My question is if it would be suitable to use a static failure theory (Von Mises) to predict the factor of safety of the bolts ? The loading conditions of this problem have been established to be a direct shear and tensile/compressive force due to the bending moment.
RE: Out-of-plane Eccentric load on bolted group
the pad reacts the compression half of the couple.
the shear is reacted by either the 2 bolts under the diagonal, or by the 4 bolts (on the longitudinal member).
another day in paradise, or is paradise one day closer ?
RE: Out-of-plane Eccentric load on bolted group
RE: Out-of-plane Eccentric load on bolted group
RE: Out-of-plane Eccentric load on bolted group
RE: Out-of-plane Eccentric load on bolted group
prying reaction is at the tip of the flange ... triangular distribution is a less conservative option.
in the example the flange is nearly thick enough to neglect prying, but the "full" prying load is applied ... maybe some reduction in prying due to stiffness of flange ??
another day in paradise, or is paradise one day closer ?