Design Steel Hinge for Wood Beam

[smokiibear]

I have a ridge beam that protudes out of a residence. The end of the beam wroughted, and I was going to remove the end of the beam and use a steel plate with bolts to connect the new beam to the old beam at the hinge. I do not design with steel, and was wondering what I need to consider when calcing sufficiency for the plate and bolts. Any references to code CBC 2001 or LRFD would be much appreciated. Thanks.

 

[COEngineeer]

So you are going to to do moment connection? So this will be cantilevered? Kinda hard to do moment connection on a beam. You didnt explain it very well. Maybe consider a knee brace for the fix.

 

[smokiibear]

Knee brace is not an option. The hinge will occur 2' from support. The cantilever extends only a couple of feet to the outside of the structure aligning with the 2' overhang. The moment is 40in-kips on a 5.875"x13.5" DF#1. Does this clarify?

 

[smokiibear]

I made a mistake...the hinge will occur 12" from the support, which has a moment of 18.5in-kips and a shear of 1825 pounds.

 

[apsix]

Calling it a hinge when it clearly is not a hinge doesn't help. Try 'moment splice'.
Use something like 6mm plate each side and design for connection to the timber beam, that will be the weak link.

BTW I don't understand "The end of the beam wroughted". Is this equivalent to the Aussie term "rooted"?

 

[csd72]

apsix,

I think he means rotted (same thing really but a bit more polite).

smokiibear,

your critical thing will be the bolt stress on the timber calculate this and see how rediculous the number of bolts is. You may decide to do it another way. I doubt that the steel design will be an issue.

Another way is to avoid the splice altogether and just slide another cantilevered joist beside it (continued under the internal floor the same distance with a couple of bolts into the adjacent joist at the end).

 

[COEngineeer]

So this ridge beam is supporting what? Do the joists in the lookout run paralel to the beam or perpendicular? Is this ridge beam dropped or flushed? If the joists in the lookout run parallel then this ridge beam carries very little weight and it might need to be there (just scab a faux beam underneath it if this is a dropped beam). But again, I have very little information. If you are willing to put moment splice on the ridge beam, it sounds like it is flushed. If it is flush then you can just sister beams right next to it and it will all be hidden.

 

[COEngineeer]

correction.. "it might not need to be there"

 

[smokiibear]

you can view a detail here:

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http://www.badongo.com/pic/627385>

 

[COEngineeer]

you are only 13' away from a column. Just replace the whole beam. Then you wont have ugly steel plate connection at random place. It makes more sense.

 

[csd72]

Replacing the whole beam would be cheaper too, you would have to shore the beam either way.

 

[smokiibear]

Thanks-replacement of the entire beam isn't an option. So far, it sounds like I need to just design the bolts and plate. But I'd sure like pointers to where I could go in the code to see it for myself.