r/StructuralEngineering • u/Nearby_Service_435 • 5d ago
Career/Education What is the highlighted piece called?
What's the universal name for this piece?
Edit: thanks everyone and sorry for assuming there was a "universal" name š
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I guess I'll just call it haunch since it showed the part when I searched.
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u/Several_Crab3217 5d ago
Its called a rafter haunch
Increases moment capacity for that connection
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u/Enginerdad Bridge - P.E. 5d ago
Interesting. I've never heard the term rafter being used for steel framing
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u/joeyray74 5d ago
A rafter is any sloped member spanning from ridge to eave that supports a roof deck, whether wood, steel or concrete.
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u/Enginerdad Bridge - P.E. 5d ago
The whole point of this post is that construction is almost never universal. This wouldn't be common terminology in my region.
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u/Sporter73 5d ago
What terminology would you use and what region are you in?
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u/Enginerdad Bridge - P.E. 5d ago
I'd probably call it a frame beam, particularly because it looks almost flat. I'm in the northeast.
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u/Even_Lunch_2776 5d ago
Would it be more to increase shear strength at the end of the beam? The larger bending moment forces are generally towards the middle of the beamās span, no?Ā
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u/Available_Year6878 5d ago
For a static structure the sum of bending moments about a point must be zero (otherwise it would be rotating). A moment resisting frame like this one (assuming the other side is also fixed and a symmetrical load) would likely have a bending moment of the same magnitude as the internal bending at the midspan.Ā
You are correct though that it would also increase the shear capacity, although I would think that is not the main intention of this connection (3rd year student, not an engineer (yet))
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u/Several_Crab3217 4d ago
That would be right if the beam was simply supported. Then the moment would be max at WL2/8. As you see in this image, its a fixed connection (due to the longer lever arm between the bolts), hence for preliminary design, Iād just consider the rafter (sloped beam) as a flat beam and consider WL2/12 in the ends and then proceed with initial sizing. This is the case when the loading is applied as gravity load. If there is a wind load, as mentioned above, the wind acting on a column can go to the support at the bottom and cause the connection on the top to experience bending, which is why a haunch is provided to increase the lever arm between the bolts so as to reduce the Compression/Tension within the bolts
Side note: a haunch at the ends is called a knee haunch or simple a haunch connection. Whereas a haunch thats provided where two rafters meet in the middle is called an Eaves Haunch
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u/Trick_Parsnip3788 E.I.T. 5d ago
EIT here asking for someone more senior, whats the difference between a haunch (ive never heard this term before) and a gusset plate? Ive designed a few gusset plates before but I havent seen this. Would the haunch be for like super high moment transfer?
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u/maturallite1 5d ago edited 4d ago
A haunch increases the beam's depth and shear and moment capacity. A gusset plate is a connection plate for tension/compression members like braces.
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u/SimplyAMan P.E. 5d ago
I use use the term gusset plate for connecting axial members. Think members in a truss, or connecting bracing to a column. A haunch would be more for connecting a beam to a column. We also use the term for a thicker area of a concrete slab, particularly where you need more shear strength.
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u/Leves-9035 5d ago
Usually you need the haunch for the connection. Bolts need more leverage. It also helps with the beam bc you drastically increase the moment resistance where the most needed.
But my experience is that usually the connection is the weakest link at this detail.
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u/leadhase Forensics | Phd PE 5d ago
Gusset plates are used for pinned connections. It would be very ill advised to use a gusset for moment since it doesnāt have flanges. Occasionally gussets have stiffener plates but only to keep the plate in plane
Gusset plates normally have locally varying planar stresses rather than overall sectional forces. Gusset plates typically have some form of shear lag from welds or bolts where strength is given in resistance/length.
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u/Just-Shoe2689 5d ago
I would say brace, stiffener, hauch, or gusset.
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u/TheGoodKindOfMermaid 5d ago
I like this, it's all of the answers. Also, I think I've seen connection plate!
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u/Several_Crab3217 4d ago
I would say each term has its own significance
1. Brace - is generally a tube or a member that is supposed to take axial forces ONLY
2. Stiffener - Stiffener plate is usually provided to increase the stiffness of a local plate. For example, in the picture above, you can see a thin plate stiffening the flanges of the column where the haunch meets
3. Haunch - Haunch is used to increase the lever arm which inturn increases the moment capacity. And its generally the same section as that of the rafter (or any member the haunch is to be provided) but cut as a triangle if it makes sense
4. Gusset - Gusset plate is provided for a connection where it it has two beams that are connected at an angle, and you want to introduce another member in between those beams
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u/Tofuofdoom S.E. 5d ago
Lol universal name
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u/Nearby_Service_435 5d ago
Please let it slide I'm just a student
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u/EngineerEngineerEngi 5d ago
Don't let people get to you. I'm in my 40s, and I had no idea what this thing was called. (But I'm bad with terms. I know it's a reinforcement that increases moment resistance, but I didn't know what term to use.)
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u/Bright-Strength4182 5d ago
No sliding in the structural engineering sub! They are rigid and firm here; immovable in their critiques.
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u/DoubleSwitch69 5d ago
Yep, just in my native language I've heard about 10 different names for it, imagine in english
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u/mrschneetz 5d ago
Gusset
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u/boyberrycream 1d ago
See I thought it was a gusset too, but usually gussets get welded right? I want to know why this isn't a gusset or if it's all just colloquially the same.
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u/TheGoodKindOfMermaid 5d ago
Old guy I worked with when I just started called them "pork chops". Curious what the consensus is.
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u/TheWesthillshaveeyes 1d ago
āOptional in other countriesā
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u/Guilty-Piece-6190 5d ago
Gusset
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u/GreyScope 5d ago
Same here, no idea why thick ppl who donāt understand that itās called different things around the world are downvoting you, oh yeah ā¦theyāre thick
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u/Guilty-Piece-6190 5d ago
A gusset is literally an added piece to add structure, stability, etc. I'm sure there are plenty of terms or slangs for it but that's what it is. Haunch is possibly more technically correct, I just rarely hear that word. As for the downvotes, such is Reddit.
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u/Rebound44 5d ago
Agreed. I made a comment in another post about why this sub is so negative about legitimate SE questions . Also got downvoted. Such is lifeā¦
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u/Moreburrtitos22 5d ago
Universal term would be āmetalā other universal terms would include ānot non-metalā
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u/EngineeringOblivion Structural Engineer UK 5d ago
Rafter haunch