Wood Moment Connection

[Lion06]

I recently saw a commercial building that had a vaulted wood ceiling. The ceiling had the sloped beams bearing on the walls and a steel plate with bolts through the plate and wood beams connecting the two beams at the peak(it looked like something I saw in the Simpson Catalog).
Is this plate meant to create a moment connection there so that the beams will not produce any outward thrust on the walls?

 

[structuralaggie]

I highly doubt it. The only moment connections in wood that I have seen was in a glulam tudor arch that was spliced at an area with low moment and this was only to make shipping easier. They did it with a lot of shear plate connectors. The connection was not a full moment connection, though. I think that would be un practicle to construct, maybe even impossible in a lot of cases. Generally speaking, I would say it is always a bad idea.

I would bet that the connection you saw was only meant to transmit axial or shear forces. There was probably something else going on, like a tension and compression ring.

 

[Lion06]

structuralaggie-
Thanks for the input. How do you suppose the keep the sloped wood beams from creating a significant outward thrust on the walls?

 

[apsix]

Construction of timber moment connections is common enough in some countries.However, steel plates and bolts is a poor choice for this type of connection due to the joint slip that will occur.
A commonly used detail is plywood gussets nailed to each side of the timber members.

More information can be found here;

http://oak.arch.utas.edu.au/research/portal.asp

 

[CJJS]

A structural ridge beam will prevent outward thrust.

 

[fratrowie]

i think that the slobe beams are so design that its stable enough to hold itself againts lateral stretch... where so trusting to the wall is'nt a problem...its all shear.

 

[structuralaggie]

As stated, a ridge beam would do it. Also, the top of the wall it self could be spanning horizontally. Was there a big beam there? Octagonal shaped rooms are often supported by a tension ring that is at the base of the rafters. What you saw could not be the real structure either. Architects will often put some nice looking wood beams that just hang below the structure. They are also really sneaky some times and hide a big piece of steel in the wood. I think that is cheating, but is done a lot. Anyway, could be a lot of things, but I would bet that it is not a moment connection.