Concrete anchoring

[bgoo]

I am trying to select a concrete anchor to hang a post (hanging vertically downward). The post have a square flange on the top with mounting hole. My attempt is to use a heavy bolt to fix the post to the ceiling. I have done a dynamic analysis, it shows the resonance frequency is in the neighbourhood of 400 Hz, which is within the vibration test range. The dynamic force is about 2000 lb (share by 4 bolts), with the static load (weight) of 50 lb. I, then, used the concrete anchor datasheet and found a anchor which is 3/8 thread. The pull out strength is 5300 lb. Assuming the bolt itself can support the dynamic load. 3/8 threaded concrete anchor seems to be more than enough for the job. Can anyone confirm my result? (I am no expert in concrete stuff). Note: Please ignore the stress cone effect between bolts as the bolts are spread apart widely.

 

[dik]

I typically don't use anchors less than 1/2" dia... and with 8" embedment, they are more than adequate for your loads. You mention dynamic analysis... Concrete has a very weak tensile capacity and you might check to see if it's possible to generate a fatigue tensile failure....

dik

 

[JedClampett]

I don't like to use wedge or expansion type anchors for any kind of vibratory situation. Since they work by crushing a small zone of concrete, I worry that the zone might progress and work loose.
Even though they didn't have a good experience with the big dig epoxy anchors (thread507-159632) in an overhead orientation, that's what I would use. Or undercut anchors, even though will have substantial overkill for your loads. Note that you should use ICBO allowables as opposed to published catalogue values.