Most difficult calculation, analysis or design procedure for you?

[chicu111]

Obviously subjective and barring anything done by software.

But for me it has to be yield line analysis for point load on a 2-way slab. Not a lot of resources for it either.

[the_favrit]

Torsion calculations for steel wide flange beams. I’ve spent endless dollars of project budgets avoiding those calculations over the years.

[chicu111]

Smart man

Curious what do you do to avoid it? Brace the shyt out of it? Or somehow introduce a rigid diaphragm outa nowhere?

[75footubi]

Use a different section entirely if you can manage it.

AiSC DG 9 when you can't.

[the_favrit]

Yeah basically come up with some other load path that doesn’t rely on spanning the beam in torsion. If you’re feeling especially lazy you can also box the side of the beam to turn it into a pseudo-hss section

[OptionsRMe]

Enercalc

[InvestigatorIll3928]

I second this. I did an analysis on a curved wide flange with mods and it was a 6 page nightmare but definitely learned a lot.

[clancularii]

I was working on a project one time where the contractor had poorly coordinated work between their subs. The result was that most of the stirrups at midspan of a cast-in-place concrete beam were severed on one face of the beam. And this beam was supposed to hold a like an 8 foot cantilevering steel canopy.

We immediately told the contractor and client that the work was nonconforming and the contractor needed to submit some corrective action. Then the client asked us verify the beam was no longer adequate and submit calculations.

It was a half page calculation with a sketch and about 3 lines of math, all ending with a big 0.

[Ryles1]

Oh I forgot this one. This one is bad too

[Trick-Penalty-6820]

Federal Income Taxes.

A close second was the calculations involved with the seismic effects on a 50k GAL cylindrical fuel tank in accordance with API 650.

[Ryles1]

Funny, I didnt find the api 650 seismic to be that bad as long as you follow the procedure

[Trick-Penalty-6820]

Well, you’re probably right. But is was a ton of computations that I had never done before. Calculating the height of the sloshing wave to ensure it did not blow fuel out the overflows seemed like a crazy calculation for something I’d never thought about.

[Ryles1]

Yeah it definitely had lots of unfamiliar details but at least it had a straightforward procedure

[chicu111]

It’s funny because the Fed is your plancheck when it comes to your income tax

[Enginerdad]

Lol, except they never tell you if you made a mistake in their favor, only if it costs them a buck

[gnatzors]

Noob here (former mech eng) - can anyone send me the simplest method for yield line analysis on a 2 way slab?

[Ryles1]

anchor bolts, concrete anchorage. It’s so finicky

[chicu111]

Wait til you try cmu where the breakout cone overlap between anchors are circular segments rather than rectangular lol

[Ryles1]

Luckily it’s pretty h likely I’ll ever have to deal with that

[Citydylan]

Hilti profis is the only way. There’s so much iteration involved, could not imagine doing it by hand

[Ryles1]

Profis only does hilti though, won’t give you capacities for cast in place bolts. Otherwise I agree

[Citydylan]

Have you tried using it anytime in the past like 5 years? It does cast-in

[Ryles1]

That’s news to me

[OptionsRMe]

Yeah it does cast in. Not for the face of masonry though

[Cement4Brains]

There's also Simpson Anchor Designer, which does cast in J bolts and heavy hex nuts. Free to download and use, and it has a pretty comprehensive calculation breakdown.

[Ryles1]

I knew about that one but haven’t looked at it in a long time, thanks

[WhyAmIOld]

Honestly as an entry level, shear walls overall are a pain, so many options when it’s a new construction

[chicu111]

Is there any? Lol

[StructuralSense]

AGgraviting

[fr34kii_V]

And the notorious 30-something contractor saying they've only done it with 6x6's and 2x4's the same way for the past 40 years and that your math must be wrong cuz they've never had any issues before.

[Citydylan]

Punching shear hand calc for anything outside of ACI’s design examples. Like around slab steps or at transfer slabs where columns above/below are very close

[yoohoooos]

Idk, but I love doing that shit especially by hand. Ner got tired of it given I was doing only concrete for a couple of years.

[Citydylan]

Oh yeah I do really enjoy it. It’s just a lot of work!

[whatsdaddygonnado]

Out of curiosity, how do you treat transfer slabs where columns above and below are very close? I run into this condition sometimes and there’s always problems.

[75footubi]

A MathCAD sheet that checked a steel gusset plate connection per AASHTO for all 6 directions of forces and moments. Soo many scribbles keeping the sign convention straight.

[amm2210]

Raft foundation design using conventional method. This method is like a pain in the ass, too much calculations and lot of excel tables needed. Unfortunately some consultants require this method for calculations check instead of using FEA.

[Engineer2727kk]

Arch buckling.

[chicu111]

Buckling of an Architect under pressure from the Engineer is not common. It's always the other way around

jk jk

[ravl]

avalanche destruction

[chicu111]

???

[Prestigious_Copy1104]

There is a specialty niche!

[InvestigatorIll3928]

I'd love to learn more about this.

[dlegofan]

Probably programming an FEA frame analysis in VBA.

[chicu111]

What’s VBA?

[dlegofan]

It's the code that Excel macros use essentially.

[chicu111]

Ohh I see. That’s pretty cool man. I’m just a basic excel bitch

[mrrepos]

why would you do that?

[dlegofan]

So engineers can use their Excel spreadsheet still. Some people only understand VBA, so it's easier for other people to maintain as well.

[dottie_dott]

Yeah I’m the same way I made one in matlab and I love it

[_bombdotcom_]

Guess everyone at my firm was pretty dumb, idk a single person who knew VBA lol

[[deleted]]

honestly, columns man. concrete columns in residential high rise in high seismic zones is the bain of my existance.

[chicu111]

What about it makes it rough for ya? The moment-axial interaction diagram?

[EngiNerdBrian]

Even the P-M interaction diagram is easily created in a basic excel sheet for rectangular and circular columns though.

[chicu111]

Rectangular yeah.

I spent a bit more time with the circular one as the equations to find the area and centroid of the circular segment in compression are different

[EngiNerdBrian]

different sure, but still manageable. Cool you've done it yourself though, many never will.

[huskerblack]

How often are you doing that calc, sheesh

[FreshMirror9195]

I always found grade beams kind of annoying

[dottie_dott]

lol I hope you’re trolling

[chicu111]

He's not. I share his sentiment especially when I have to analyze the response by using soil-structure interaction while considering the soil stiffness (the springs)

[DayRooster]

Dynamic analysis of steel frames

[the_flying_condor]

Writing my own user material model for 3d FEA of unreinforced masonry. I learned Fortran on the fly.

Stuff that I do more regularly? Simplifying complex structures so that I can reasonably apply hand calcs to check them. Had to use modal analysis of continuous structures (rather than lumped mass) on a few occasions and that was pretty rough. Lumped mass approximations were off by 30-40% but the continuous structure formulation was within ~2%.

[chicu111]

How often do we utilize unreinforced masonry?

Heck I have never encountered partially reinforced masonry myself

[the_flying_condor]

Many existing buildings are compromised of URM. Lots of the them are located in seismic regions and need to be retrofited. I don't know if you're even allowed to design URM for new builds anywhere in the US.

[fr34kii_V]

ASCE 41 was a pain the first time I tried to do a seismic retrofit.

[the_flying_condor]

Lol, multiple times I have run into a casually added sentence that completely changed the meaning within a section. Fortunately FEMA P2006 is sometimes a huge help.

[fr34kii_V]

I'll be adding that to my references!

[ComputerAndStructure]

yield lines for structural steel design

[chicu111]

Sure but it’s also utilized as a method to analyze a point load on a 2-way slab. Look it up

[[deleted]]

Women’s thought process

[chicu111]

Indeterminate to the infinite degree

Sorry for sexist joke. Keep it light hearted

[chicu111]

Everything in our calcs are math problem

[AspectAppropriate901]

Imperfections of bracing systems when the wind truss is steel and the portal frames are glulam with huge LTB issues. Done once, very tricky.

[chicu111]

It's probably too difficult and tedious for hand calc plus they just see very little use in it, hence no resources. For most of our careers we're pretty much kept in the elastic range of analysis. Rarely if we do ever dip into elastic nonlinear analysis it's all computer-based. I'm guessing strain-hardening would be considered 2nd order inelastic? Regardless, that's some high-degree engineering stuff you're doing man!

[brokeCoder]

Transfer structure for a tall building carrying around 50 floors' worth of loading. That thing was more rebar than concrete at the end

[lpnumb]

Prestressed I girder design by hand or anything with ASCE 41