Bending of a 2 1/4" diameter bolt.

[RARWOOD]

I have a design application where I am unsure as to whether or not I have to take bolt bending into account. After reading the postings on this forum and the fact my bolt is so much larger than the attachment plates, I don't think bolt bending is a concern.

One posting explained that beam flexural theory is based on a member with a long span and does not apply to a bolted joint. Most bolted applications in steel have plates lapped and flush against each other. In my case there is 6 3/4" space between my attachment plates. So I have a suport then a load applied near the support and then a 6 3/4" length of bolt, then another load applied near the second support.

I have a 2 1/4" dia. x 12" A325 bolt I am using as a shear pin. The bolt extends through two 1/2" thick plates that are spaced 9" apart. The bolt is loaded by a truss tension member inserted between the 1/2" support plates.

The tension member is made up of a 6 3/4" x 15" glulam,with 1/2" plates bolted to the glulam. There also is a 1/2" spacer plated welded to the glulam side plates. This reaults in a total width of 8 3/4". The glulam assembly fits between the 1/2" support plates. The load is transferred out of the glulam member into the 2 1/4" dia. bolt, through the bolt into the two 1/2" side plates.

In this case should I be concerned about bolt bending?

 

[arto]

For comparison - kinda similar: ASME B16.5 requires that flange bolt spotfaces be square to the cL within 1 deg|:

par 6.6 "Flanges and flanged fittings shall have bearing surfaces for bolting that are parallel to the flange face within
1 deg."

 

[IFRs]

I would be concerned about bolt bending. NDS codes include bolt bending in the allowable stress calculations of the timber member. It should be easy enough to calculate the bending moment and then the combined stress in the bolt. Now that you have thought about it, just follow through and be done with it.

 

[RARWOOD]

Thank you for your thoughts. I have reviewed Appendix I of the NDS and don't feel it is applicaple to my problem. The situation I have is not a wood design problem. Rereading my problem description, I can see that it my not be clear to some one who does not design in wood what I am describing.

In the connection I am describing the wood is not in contact with the 2 1/4" diam. A325 bolt. The load in the glulam is transfered into 1" diam A307 bolts. The 1" diam bolts transfer the load into 1/2" side plates. The load in the side plates is then transfered into and out of the 2 1/4" diam bolt through a steel to steel connection.

To assure no load is transfered through the A325bolt into the wood, the glulam is either held back from the bolt or the hole in the wood is oversized to prevent contact with the A325 bolt.