Bolt failure of two bolted I-Beams

[snoel371]

I have (2) 8 X 5.25 x 20 WF I-Beams that are 4.5 ft apart. I need to attach a standard 6 X 3.38 X 12.5 I-beam to the bottom of the two wide flange beams. I want to use ASTM A-193 B7 bolts and nuts which have a tensile strength of 125 ksi and a yield of 105 ksi. I would use four (4) bolts per beam. I need to be able to hang an 8000 lb load in any position along the length of the beam.

How do I figure if the bolts will be sufficient? I can look at the tensile stress area of the bolts, but what is the worst postion the load will be that will create the largest force? I'm not sure if shear is a factor either.

 

[JedClampett]

If you have a structural engineer handy, you should talk to him/her.
You didn't give the bolt diameter, but assuming for a structural connection, 5/8 diameter is the smallest used, your bolts will probably be OK. But you're using nomenclature for the beams that isn't standard, so I'm not sure how your connection looks or even what size the members are. There's a lot more to a connection than bolt material, number and size, so you should get some help from someone who's done this before.

 

[snoel371]

I apologize for forgetting the bolt size. I will be using 0.75 bolts. The newer nomenclature (as shown in the Machinery's Handbook for the I-beams are two (2) W 8 X 21 (8" deep, 21 lb/foot) and the other is a S 6 X 12.5 (6" deep by 12.5 lbs. per foot). The standard beam will be bolted under the two wide flanged beams spanning from one to the other. Two wide flanged beams will be parallel to each other and the standard beam will be perpendicular to the other two.

 

[JedClampett]

The issue you're going to have is the flange width of the S6. The flange is only 3 3/8 inch wide. There's no flange gage even listed for that size member. If you were to space the bolts at 2 inches, there's only be 11/16 inch between the centerline of the bolt hole and the edge of the flange. This violates the code minimum edge distance.
If you use an S6 x 17.25, I think everything else will work out.

 

[hokie66]

Probably best to use a W6, because the S6 members have tapered flanges.

 

[jberg]

Another option, albeit a possibly expensive one is to use Lindapter connections (

http://www.lindapter.com/).

The last time I priced them out, they were 2x the price of ordinary bolted connections, but for the S6 it may be an option. They have a connection builder (

http://www.lindapter.com/Assemblies/13/1/GC001-1)

which might work depending on your configuration.

JWB

 

[paddingtongreen]

The old tables show no bolt gauge and no bolt size, it is too small for the minimum of 2" and 5/8".

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[dcarr82775]

The largest load in the bolts would be if the load is directly below the W8 beams but as others have pointed out you can't fit the bolts and maintain edge distances. Can you weld the beams together?

Since you are using an S shape I assume there is a hoist(chainfall) that attaches to the S beam. OSHA has all sorts of additional requirements for the structural capacity if hoisting loads are present.

 

[csd72]

snoel371,

You really need to get an experienced structural engineer involved in this as I am reading very large gaps in your knowledge by what you are posting.

This forum is not a place to learn engineering fundamental nor is it a place to get professional advice.