Best Connection: Post/Beam/Post

[kmart30]

Attached is what we are dealing with. Have had a little debate as to the best connection for this situation and I thought Id ask the pros!

This is a 3 story wood deck in a fairly high wind area (no seismic). The deck is 10' wide by 40' long and is attached to the structure with a ledger board. I know there are a few options but here is the criteria:

strength
ease of construction
most economical

Thoughts?

 

[XR250]

Depends if you have any shear at the bottom of the posts from bracing. Best is probably something on the order of 1/4x4" x 32" vertical strap that bolts to each member.
Might be able to get away with toenails and an LSTA24 strap. I don't know how much money or time i would be trying to save on a deck of this scale and potential liability.

 

[dik]

If you can, post to U/S of deck with beam hangers for LVL's secured to the side of the post and new post above. secured to LVL's with proper base plate.

Dik

 

[racookpe1978]

The sketch isn't clear.

Are you stopping (interrupting) the vertical 6x6 at the joint with the 2x horizontal LVL beams and the 1x 2x12 horizontal beams?
Would it not be better to continue the 6x6 all the way up, and connect the horizontal beams to the continuous vertical member with Simpson galvanized steel ties? (Or the equal product.)

 

[phamENG]

Will the column be wrapped or exposed? If wrapped, you have a few more options. There's a post splice detail published by the City of Chicago for use on large residential decks that I've made use of in the past. It's not very pretty, though, so I only used it when the architect was going to hide the post anyway. You could also consider an engineered wood product. It wouldn't be cheap, but you can special order PSLs up to 60 feet, I believe - you're only limited by the size truck you can get to your sight. That way you can run the post continuous and either make it big enough to notch and provide a recessed bearing seat or use an offset, face mounted hanger.

If it's not wrapped, you'd have to consider the bracing of the deck. If it's adequately braced by the main structure so, as as XR250 mentioned, there is no lateral shear, you could design a pinned base - maybe drill into the posts and drop a stainless steel drift pin in, or use a concealed post base with modified loads based on your substrate connection. If the 40' dimension is against the wall, I would imagine it's pretty well braced. Just make sure you pay close attention to the detailing at the attachment and load path into the house diaphragm.

 

[kmart30]

Of course they dont want bracing on this one. We have to use tiebacks and diagonal laid decking to take care of lateral loads. I was thinking notching the post for the beams to sit flush with bolts and strapping the top post to the bottom with 14ga. coil straps. Someone mentioned that notch being too large and to use a heavy duty Simpson post cap but that leaves you no room to strap the top post to the bottom....

 

[kmart30]

yes the posts will be wrapped. Also its very close to the beach so corrosion is another variable to deal with....will probably have to be stainless all the way.

 

[phamENG]

If the notch size is a problem, can you look at a larger post? Make it large enough that the remainder can carry the axial load alone, or add the axial load to the beam bearing stresses to make sure you don't crush the beam.

Your multi-ply LVL should be fastened (and possibly glued) along its length. Have you considered a partial depth bearing ledge supplemented by bolts? Design the bearing ledge to handle the full reaction, and then use the bolts to counter the bearing eccentricity and act as insurance (design them full the full gravity load, too). Or, like I said, use an offset or concealed flange hanger for the beams on the side of a continuous post - that may be harder to get in stainless, though.

I have the exact same condition with a multistory apartment with balconies a block from the beach. I intend to use the splice detail I linked to above at mid height between floors, and the post cap at the roof level.

 

[BadgerPE]

I always spec Simpson concealed flange hangers (HUC) for the (2) ply edge beam. Contractors seem to prefer this since they can install all the hangers for a column on the ground before setting. This of course doesn't help with your bracing, but eliminates the need for funky strapping or notching of your post.

 

[XR250]

Would it not be better to continue the 6x6 all the way up, and connect the horizontal beams to the continuous vertical member with Simpson galvanized steel ties? (Or the equal product.)

Getting a straight 6x6 of that length would likely be challenging

 

[bhiggins]

Would such a detail be sufficient? It's a lot of steel, but I think this condition warrants it because there are not any standard off-the-shelf components for this condition. This detail assumes there is sufficient bracing of course.

For a 3-story deck I would automatically just do 6x6 HSS steel columns.

 

[HouseBoy]

Some thoughts:

LVL's (even if wrapped) are vulnerable to deterioration in damp conditions like this and I would not be happy with that material in this application.

Simpson concealed flange hangers for posts are good for this.

Thinking of lateral stability - Seems like the 4:1 aspect ratio of the deck is very favorable for lateral stability, provided that horizontal anchorage can be provided by the connection at the building.

I like PT PSL or Glu-lam posts (Anthony Forest Products makes a nice PT Glu-lam post).

 

[BAretired]

Continuous steel or glulam columns would be a good solution as suggested above but probably not the most economical. For ease of erection, I would prefer single tier Timberstrand or similar columns spliced top and bottom of edge beams, i.e. platform framing as opposed to balloon framing.

BA

 

[dik]

or something like the attached (wrong drawing earlier) Use 3/16 plates and glulam rivets.

 

[dik]

Should have noted that the lumber should be PSL and not LVL for exterior exposure and pressure treatment.

Dik