Need assistance with ..

[susanp]

I need assistance designing a small structure to support a 2000 lb transformer. It is to be mounted on an angle fram supported from a plate bolted through a 12'' masonry wall. Not sure but I think a 3x3x1/2 angle fram with 1/4'' thick plate with 4 1/2'' bolts will do the trick. any feelings?

 

[whyun]

Selection of the beam carrying the transformer depends on the span. In any case, if it is indeed a BEAM, I wouldn't use an angle. More appropriate type is either a wide flange or a channel with a wide enough flange to receive the bolting from the unit.

 

[susanp]

the span is 54'' in the one direction and 36'' in the other. I also forgot to mention that the transformer is supported on top of 2 vibration isolators on the long sides. There fore we are dealing with 2 points loads on the long members, rather than a uniform load.

 

[whyun]

I hope you are not confusing equipment footprint dimensions. If supported on vibration isolators there are higher coefficients for determining lateral design forces. The design, in my opinion, should be done by the SEOR of your project (provided that SEOR is compensated for the efforts).

 

[susanp]

Thanks for the input. Maybe beam wasn't the approipriate term. We are trying to mount the transformer 9'aff and need a frame to support it. My boss asked me to do the design (my original degree was in structures - never practice always been mechanical therefore I have lost a lot of what I once knew. In any case thanks for the response.

 

[EddyC]

Sounds like you're trying to cantilever the transformer off the wall? If so, I would be concerned with bending stress in the wall.

 

[UcfSE]

EddyC has a good point. You will need to evaluate the wall for that moment also. A 12" wall is pretty hefty though, it may not be a problem but you still need to check for good measure. Whether or not your bolts work will depend a lot on the size of your frame. I would go with bigger bolts personally, and epoxy grout them at that. Again, it all depends on your frame. If you have a large distance between upper and lower bolts, the tension force will be smaller but your frame bigger. If you want your frame smaller then you will have larger forces on your bolts. You should make sure you can get the bolts into solid grouted cells also, not through the hollow masonry, so the rebar spacing in the wall may be a factor in determining the size of your frame also. I would try to use several, at least two, bolts at each connection and would probably use an extra factor of safety over and above the bolt manufacturer's minimum, such as 8 instead of 4. That isn't so unreasonable as it corresponds to not having special inspection of the bolts as they are installed.