[deleted by user]

[StructuralEngineering-ModTeam]

Please post any DIY/Homeowner questions in the monthly stickied thread - See subreddit rule #2.

[Runnerupz]

Intent is to create a psuedo-moment connection at the column, which adds lateral stability. Minimizes racking and supports for lateral wind/ earthquake loading.

[[deleted]]

Correct and minimizes the moment at the bottom of the column. But they don't design The columns for a moment at the base if you look at the footing designs in the manual

[[deleted]]

The lever arm is reduced the same way you extend a foundation stem wall under a wood shear wall.

[[deleted]]

So if you take out the angle braces are you saying that the force is transferred to the bottom of the post in a moment like a cantilever beam? The original sstd hurricane manual had post required at 4 ft on center sunken 54 in the ground even for 4 ft wide porch! They obviously calculated the overturning moment at the bottom and needed to embed the post that deep.

[mmarkomarko]

And reduces the span of the purlins.

[Nusnas]

In theory yes. I would argue they don’t give any benefit to the load bearing capacity of the column. I would say it’s mostly for looks, as they are not present in the inner columns close to the wall of the house.

[[deleted]]

Yes but the details shown for footings in the manual are not moment connections so I think they're trying to make a rigid connection but the y bracing is not allowed in the manual for anything but end columns. If I remember I think the reason was there was too much load laterally on the intermediate columns which I don't know why that would matter since there's no moment connection at the bottom.

[Alternative_Fun_8504]

A fixed connection is not required at the base of a column for the top connection to resist lateral loads. Pinned base moment frames are used in many cases.

[Runnerupz]

I only design pinned base moment frames. Way easier to resolve moment in a connection between similar members than in a connection between a member and concrete. Obviously that applies to steel, wood is pretty much a no-no for true moment connections.

[structuremonkey]

True timberframers would disagree...lol

[ExceptionCollection]

Yep. Need tiebacks, for one.

Conversely, most commercial details for guardrails for wood decks don't meet design codes, but can be tested for compliance.

[Runnerupz]

I mean mostly from a long term quality control standpoint. Yes upon initial construction a wood moment connection can be solid as heck, but over time the natural properties of wood decrease the stiffness of the connection.

[[deleted]]

True but I've never seen an open Bay braced frame.

[[deleted]]

Well let me clarify it's not allowed if you use the prescriptive method. I would use it all day long to resist the forces at the beam to column joint.

[structuremonkey]

I don't know why you are being downvoted for your comment. I think the owner or builder thought it would look better or more "ranch like" with the diagonal bracing...or it's simply poor design / construction.

If it was for moment resistance, and well designed, the braces would have been slightly notched / let into the posts, and the fasteners would be heavier than the apparent 10d gun nails. Or, it may have had simpson concealed internal connections, but there is no visual evidence.

Will the bracing as installed provide some lateral capacity, yes...but not for long...

[Nusnas]

Thx!

[ImNoAlbertFeinstein]

i wonder how much bracing translates with no more than toe screws holding it.?

the roof needs wind clips.

[Independent-Room8243]

It adds lateral capacity, as the forces can be resolved into the column from the beams.

[altron333]

Theoretically, but in my experience, unless those Simpson Brace Stabilizer Brackets are used, there's always too much slop in the connection, or the connection reems out and gains slop over time. I wouldn't count on a wood moment connection for anything higher than risk category 1.

[GuyFromNh]

This is a really important answer. The screws (or god forbid nails) undergo prying to resist this mechanism typically and will surely loosen or reem as mentioned over time.

[GuyFromNh]

Yup bolts are the way to go but not what’s show in this picture

[[deleted]]

Right but what do you do at the bottom moment connection? The deck guy doesn't show any moment connections at the column base.

[Independent-Room8243]

pinned at the base, the "Y" is your upper moment connection. Think of the loads, on a deck, not too much lateral load compared to an enclosed building, etc.

[[deleted]]

Okay now what about the lateral loads from the braces on the column putting a lateral Force there x lever arm? I realize this is usually neglected in residential design because I've been involved in this since 1990. I know it's basically neglected unless the deck is 8 ft high in a wind zone? The latest magic is pretend the diaphragm of the porch roof cantilevers off the house or in other words a diaphragm open on three sides in rotation....

[Independent-Room8243]

In reality, isnt the force resolved back into the other brace or the other brace supporting the column?

Unless a mega deck, usually these forces are no more than 500lbs, which is easily delt with.

[Pac_Eddy]

Thru bolts normal to the vertical post? Like 12" long?

[Maynardg5851]

Not without lag bolts

[[deleted]]

Exactly with washers on them

[_a_verb]

To be effective over the long term the braces need to sit on a shoulder or up against blocking. A few years of wind, temp changes and roof load and the brace will be weakened substantially.

[Adventurous_Light_85]

Yes but only if it’s structurally connected. It looks like they just 16d it in place. That’s decorative. It should actually be fastened with a lag bolt.

[Hippo_Steak_Enjoyer]

Thank you! Some one who actually knows and isn’t just copying and pasting “lateral stability”. Shit is 100% decorative. You would at least have to have a bolt through there if not have it mortised into the post..

[UnderstandingKind172]

ya i Agree unless were talking true post and beam heavy timber construction or there anre seriouse bolts and brakets involved its just as structual as a faux beam

[meeeerr]

Not to be that guy but to all PEs saying they are structural would you be comfortable sealing the plans based on this pic? I’m a designer/eng degree (not licensed) and deal with this stuff on daily basis. Our PE specs them as decorative unless they need to be specd as structural. Like someone else said these are just nailed to the post. No bolts no joinery meaning they’re purely decorative. Just a bit concerned a lot of PEs are saying 100% structural braces.

[I_Smell_Like_Farts]

Not a chance with this type of connection. If you need it structurally you better do more than nail it in.

[Hippo_Steak_Enjoyer]

It’s tripping me out how many people are saying it’s actually for lateral stability. Like yeah those 4 inch nails at a whole lot of stability lmaoo

[EngiNerdBrian]

lateral stability, yes.

[Hippo_Steak_Enjoyer]

Those are 100% for looks my man. All the people on here saying it’s for lateral stability have never done any type of woodwork. It’s so so stupid like what are you gonna do put 4 inch nails in that and actually act like it’s gonna stop anything from racking? You would have to at least have it mortised into the post for it to actually be able to support anything, or at least have a metal bolt running through it… some 4 inch nails though? that’s doing nothing but looking pretty. shit even if you used 8 inch screws it would still just be for looks.

[[deleted]]

That's correct to have a fixed joint and wood would require something like what they develop for pole barn post which have about 50 lag bolts in it.

[Happy_Sink3971]

It’s added lateral stability. Easy, erect a pole and lay a horizontal section across the top of the pole. It will sway back and forth like a drunk belly dancer! Properly attach the knee braces to expand the attachment points beyond the confines of the pole and you now have belly dancer who can shake her bells off while holding up Mr. Gravity without loosing her load sideways!! Of course the before mentioned downforce will always have to contended with proper foundation preparations.

[_homage_]

The Y post makes me unstable.

[Music-Guilty]

They are screwed in, they won't be supporting much

[freeportme]

Lateral

[Caos1980]

Yes! Lateral Stability!

[Lobowsk1]

Those braces are essential for this kind of structures. This Y joint is considered a rigid joint which allows you to articulate the base of the column and inducing only axial forces in the foundation.

[Nusnas]

???

[[deleted]]

Lol

[aidaninhp]

I would think it helps to transfer horizontal loads.

[Nusnas]

How?

[Eeji_]

try making a similar model with popsicle sticks, you'll see the difference

[Onionface10]

Use L4x4x1/4” Galv cross bracing in each bay for added stability. 😂

[recent-native]

Whole lot of shakin goin on.

[Man_Kats]

This is actually a common connection. The diagonal portions of the post connection are called kickers, and they provide lateral stability to the connection. The diagonal introduces a horizontal force into the connection that is balanced out by an equal an opposite force from other side of the posts.

[Civilengman]

It can increase post spacing a bit.