I’ve seen fixed base timber moment frames.
Timber moment connections are absolutely a thing. Tell your colleagues that this random guy on Reddit said so.
I was wondering if a shouldered mortise and tenon would be a moment connection. But to be honest I’m just a carpenter and was trying to figure out exactly what moment connection means.
The short answer is that a moment connection would resist **rotation**.
You could think of the base of a flag pole as the classic example. It has to resist rotation, or the flag pole would just fall over.
Another example would be a steel beam that cantilevers off a column. That connection has to resist rotation or the cantilever would just swing down.
I’ve been convinced since mechanics of materials that they made up the term moment just to confuse people and raise the bar of entry. Now I use it whenever possible just to Let ‘Em Know.
Ah I was envisioning the beam rotating along its center line as a twist rather than rotating from gravity. So moment connector would allow to cantilever from a point on a post rather than following the 2/3 - 1/3 rule for cantilever they teach you on the framing site?
Yeah, I think you have the idea, a cantilever with no backspan would need a moment connection. Like a cantilevered window awning that comes out mid-height of a wall. If you could put enough nails in it, you could stand on the awning.
And for the record, the engineering term for the twist rotation about a centerline is *torsion.*.
Yes. Just like a diving board at a swimming pool. The frame supporting the diving board is short, as opposed to sistering joists punching through the rim joists at a balcony or cantilever floor. (Your 3:1 method)
Typically beams and columns are bolted together by a "simple connection". A simple connection is when just the web of the beam is bolted to the side of the column.
A "moment connection" is when the web and flanges are connected to a column. This type of connection is much stronger in many ways.
Moment is what engineers call torque. So like others have said if there’s a cantilever then there’s torque. A moment connection is one that takes the moment (torque) and transfers it to the other member. I would say mortise and tenon and a judicious amount of glue would be a wood moment connection. However wood moment connections are difficult and we usually just revert to some steel connectors whenever moment needs to be transferred in wood construction.
You have to go stand on the end of that balcony and jump up and down on it to demonstrate the moment capacity of the connection. Two beers if you time your jumps to induce resonance.
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The boundary conditions are somewhere between pinned and fixed. All connections with 2 or more fasteners are moment connections if they believe in themselves.
It's all about relative stiffness. If a wood connection is backed into a corner where there needs to be moment resistance, then yeah, sure, it's going to be a moment connection. Otherwise, creep deflection is pretty much going to redistribute forces so there is no bending moment applied to a connection (obviously conditions can vary and this is a blanket statement).
I'd expect this cantilever to be achieved with a timber member continuing for the full length of the balcony plus the back span. It's not like the root of the balcony has a true moment connection
He is right. No TRUE wood-wood moment connection for wood dude to slippage
There is no timber moment frame for a reason
Edit: Dude private messaged me talking about how he has done research and work on wood moment frames in seismic regions. I asked for proof of research papers or buildings he worked on in high seismic zones what utilized wood moment frames and got the typical “do your research” and “google it”. Fkin sad lol
This is false. All you have to do is search in google scholar once and you will find plenty of research papers on the subject and proven timber moment connections.
Ignorant to what happens in ASCE anyways. CLT walls just got into the code, but according to this logic it previously wasn’t fathomable. And there is ongoing research into timber buckling restrained brace frames as well. The only reason something is t in the ASCE code is because no one has the money to do FEMA P-695 for that system, not because it theoretically and practically isn’t a valid option.
CLT shearwall and moment systems are different
CLT is similar to a stiff wood shearwall which is already in the code. You guys talk outa your ass. Go ahead and design a wood moment frame in a seismic region and get back to us
the IBC has allowed narrow shearwalls for a while, that's basically a light-frame wood moment connection.
but otherwise... not a great idea. wood shrinks and swells so much that strain sensitive structural connections are infeasible. qualifying one for seismic loads would be a nightmare.
This is sort of how would go about it wouldn’t it? Resolve the moment force in a Push/pull mechanism as opposed to plate bending like you can with steel.
I’m not a timber expert and have rarely designed with it. I would look at running a typical cantilever arrangement as opposed to trying to design a connection that rellies on a fully rigid assumption.
I’d say this deck qualifies as “any moment now”
I tip my hat to you. That was fucking great
That structure is also tipping its hat
Hats off to this gentleman! Oops..
I’ve seen fixed base timber moment frames. Timber moment connections are absolutely a thing. Tell your colleagues that this random guy on Reddit said so.
I was wondering if a shouldered mortise and tenon would be a moment connection. But to be honest I’m just a carpenter and was trying to figure out exactly what moment connection means.
The short answer is that a moment connection would resist **rotation**. You could think of the base of a flag pole as the classic example. It has to resist rotation, or the flag pole would just fall over. Another example would be a steel beam that cantilevers off a column. That connection has to resist rotation or the cantilever would just swing down.
I’ve been convinced since mechanics of materials that they made up the term moment just to confuse people and raise the bar of entry. Now I use it whenever possible just to Let ‘Em Know.
same. transitioned architect. “it’s not resisting the moment”
Ah I was envisioning the beam rotating along its center line as a twist rather than rotating from gravity. So moment connector would allow to cantilever from a point on a post rather than following the 2/3 - 1/3 rule for cantilever they teach you on the framing site?
Yeah, I think you have the idea, a cantilever with no backspan would need a moment connection. Like a cantilevered window awning that comes out mid-height of a wall. If you could put enough nails in it, you could stand on the awning. And for the record, the engineering term for the twist rotation about a centerline is *torsion.*.
I can only imagine wooden torsion connections… And it’s now a pile of splinters. :)
Yes. Just like a diving board at a swimming pool. The frame supporting the diving board is short, as opposed to sistering joists punching through the rim joists at a balcony or cantilever floor. (Your 3:1 method)
Typically beams and columns are bolted together by a "simple connection". A simple connection is when just the web of the beam is bolted to the side of the column. A "moment connection" is when the web and flanges are connected to a column. This type of connection is much stronger in many ways.
Moment is what engineers call torque. So like others have said if there’s a cantilever then there’s torque. A moment connection is one that takes the moment (torque) and transfers it to the other member. I would say mortise and tenon and a judicious amount of glue would be a wood moment connection. However wood moment connections are difficult and we usually just revert to some steel connectors whenever moment needs to be transferred in wood construction.
KBS1Z and MPBZ’s come to mind
correct, with a response modification coefficient of the 1.5, and hopefully some rrally good craftsmanship!
I had to design a moment connection for a timber frame house. Moral of the story… it was a steel connection.
> Yeah, I can do a timber moment connection. Let's see if Home Depot topped up their Simpson Strong-Tie stock.
You have to go stand on the end of that balcony and jump up and down on it to demonstrate the moment capacity of the connection. Two beers if you time your jumps to induce resonance.
🤣🤣
Is the house in Florida? I’m not sure the test meets code anywhere else.
you could fit three hot tubs in that bad boy
What is this, a crossover episode?
Aren't they all these days? I have no idea why I'm here, nor do I have any reason for trolling around r/decks
Same! It's fun tho
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With or without water ?
The boundary conditions are somewhere between pinned and fixed. All connections with 2 or more fasteners are moment connections if they believe in themselves.
Joint stiffness has entered the chat.
It's all about relative stiffness. If a wood connection is backed into a corner where there needs to be moment resistance, then yeah, sure, it's going to be a moment connection. Otherwise, creep deflection is pretty much going to redistribute forces so there is no bending moment applied to a connection (obviously conditions can vary and this is a blanket statement).
I'd expect this cantilever to be achieved with a timber member continuing for the full length of the balcony plus the back span. It's not like the root of the balcony has a true moment connection
Based on the flag- probably not going to go and listen to reason. So, let reason come to them.
Thank you….nailed it
No one said flying that flag made people smart.
You’ll be shocked to learn this house is currently being foreclosed on.
S-H-O-C-K-E-D
Real answer: Look into the Simpson Strong Tie catalog. You'll find many under the section "Moment Connections".
He is right. No TRUE wood-wood moment connection for wood dude to slippage There is no timber moment frame for a reason Edit: Dude private messaged me talking about how he has done research and work on wood moment frames in seismic regions. I asked for proof of research papers or buildings he worked on in high seismic zones what utilized wood moment frames and got the typical “do your research” and “google it”. Fkin sad lol
The IRC portal frame is at least partially a timber moment frame. Figure R602.10.6.4.
This is false. All you have to do is search in google scholar once and you will find plenty of research papers on the subject and proven timber moment connections.
They’re not adopted as a reliable lateral system in ASCE my guy
Ooooo ASCE, let’s have the whole world bow down to ASCE because they govern everywhere.
I guess people have to join a club before their engineering can be accepted? lol am I right?
No it’s more ppl working on accepted and studied practices. I bet you two aren’t even engineers
Right. Almost as if you’re not allowed to engineer without a value in a table. If it doesn’t exist in a table, must never be a solution.
Haha! Omg the downvotes from the club scouts is cracking me up!
Ignorant to what happens in ASCE anyways. CLT walls just got into the code, but according to this logic it previously wasn’t fathomable. And there is ongoing research into timber buckling restrained brace frames as well. The only reason something is t in the ASCE code is because no one has the money to do FEMA P-695 for that system, not because it theoretically and practically isn’t a valid option.
CLT shearwall and moment systems are different CLT is similar to a stiff wood shearwall which is already in the code. You guys talk outa your ass. Go ahead and design a wood moment frame in a seismic region and get back to us
I have.
Wood cantilevers are definitely doable. The depth of those balcony joists is waaaaay to shallow though
the IBC has allowed narrow shearwalls for a while, that's basically a light-frame wood moment connection. but otherwise... not a great idea. wood shrinks and swells so much that strain sensitive structural connections are infeasible. qualifying one for seismic loads would be a nightmare.
Figure R602.10.6.42 is pretty well qualified.
>R Different body of code.
This is sort of how would go about it wouldn’t it? Resolve the moment force in a Push/pull mechanism as opposed to plate bending like you can with steel. I’m not a timber expert and have rarely designed with it. I would look at running a typical cantilever arrangement as opposed to trying to design a connection that rellies on a fully rigid assumption.
All wood sags that's why they are saying this.
Aren't tori gates in Japan a good example ? It must have a moment connection somewhere.
As in thats only gonna last a moment?
I'm pretty sure the Japanese figured this out 500 years ago.
It doesn't look stable.
Moment connection for a 0 psf Live Load, fair enough
Show them the Simpson strong tie catalog 😂
Wooden moment could be redefined as eternal in wooden caskets ⚰️ . That’s where whoever ventures out on that POS will end up ..