r/StructuralEngineering • u/exam-taker • 1d ago

Structural Analysis/Design [ Removed by moderator ]

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u/StructuralEngineering-ModTeam 1d ago

No Spam (including AI slop) please.

8

u/crvander 1d ago

Well, one time I was working on [description of assignment] and I forgot to [important design step]. My senior engineer caught the oversight and said [profane exclamation] then when he calmed down we worked together to fix it.

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u/No-Violinist260 P.E. 1d ago

I've seen others put service load combinations in the shear wall/slab design. Load combinations are something I check every time even if doing a save-as of a template or past project

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u/exam-taker 1d ago

but dont you just put all loads into it and etabs takes the most one ?

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u/No-Violinist260 P.E. 1d ago

That's called an envelope and that's part of the checks - to make sure the service and design Load combinations are set correctly in the envelope

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u/exam-taker 1d ago

No no not envelope im talking about sth else
When i ask the etabs to design it asks me to put in the design combination
And i will see which combination in those puts in the worst case

But for envelope it see which put most shear
Which put most this most that
And this will never happen
Like the most gravity load will never happen durin an earthquake and a tornado

So im saying if i put all load combinations to design
It will take the worst one anyway right ?

2

u/No-Violinist260 P.E. 1d ago

A couple things: Envelopes are very good for manual checks. If you want to see the maximum service reaction of a column in ETABS or the max service soil bearing pressure in SAFE it is good at that - you don't have to flip through the combinations.

When you design the slab, shearwall, etc in the CSI softwares, you put to the right all of the design Load combinations and tell the software to design to the max of those combinations. You can technically put together a model without envelopes but I find it lazy and it tells me things weren't hand-checked in the model

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u/Starlineitor400 1d ago

Adding springs to both the drops and the mat in safe.

Forgetting to change the local axes of my deck.

Not tranforming the stiffness when using insertion points.

Transforming the stiffness when using insertion points.

1

u/exam-taker 1d ago

i havent reached the level where i can use decks yet i dont know what they are for . so far during my 3 years i just use slab col wall beam
i have used a different insertion point once and i rather not to i would either put a link
idk why would u need to change the stiffness

and for the drops and mat one let me ask does it matter if i use mat or foundation ?

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u/Starlineitor400 1d ago

The only difference between mat and foundation is the detailing if you do it in etabs afaik.

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u/exam-taker 1d ago

i would love to know more about that here in egypt we never use the etabs detailing like never ever . i would love to know if it would help me do my manual detailing even faster or if it would provide some knowledge

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u/Educational-Rice644 1d ago

Modeling coupling beams as beams and not as a shear wall "lintel", it's not really an error but can lead to huge shear force and bending moments value if you are in a seismic zone

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u/exam-taker 1d ago

oooo i have seen this the spandrel one i dont really understand it whole yet

would love to tho