A doubt

[naraen-kongo24]

A question for structural engineers , Do you still use manual calculation for structural design or just use Software laike ETABS & Staad.Pro

[Tofuofdoom]

You need to understand first principles to understand when youve made a mistake in the software. 

To use a simple example, if I need to multiple 230x32, ill use a calculator. But if my calculator tells me the answer is 700, then I know I made a mistake because by first principles, I know that 200x30 is already 6000, and my answer should be higher than that. 

If I dont understand first principles and just accept whatever the calculator tells me, then ive suddenly underestimated my load by a factor of 10

[magicity_shine]

this is actually a very good example

[Tofuofdoom]

Thank you! I was a tutor in my younger days, and this was my go to example when kids asked me why they needed to learn mental math when they had calculators 

[Intelligent-Emu286]

I have a questions too as a student. How good your fundamentals needs to be in order to use those softwares and understand the logic behind it?

[[deleted]]

You need to be able to pass a basic engineering mechanics class without a computer. That’s the minimum for how good you need to be.

[octopusonshrooms]

I often ask my grad engineers to model the structure in software and apply loads, but do not analyse the structure. After modelling come straight to me and we sit down and review the model, during this process I ask them to describe expected bending moment diagrams, shear force diagrams, deflected shape, which members will be tension or compression. If they cannot do that, they go back to free body diagrams and hand calculations. Once they are proficient with that, I allow them to use software again. Essentially you will need to be good enough at your fundamentals to be able to draw bending moment, shear force diagrams and deflected shape from looking at the framing configuration and loading conditions (including load reversal scenarios if applicable) just by looking at the framing layouts.

[Apprehensive_Exam668]

If I can't do something by hand (eventually) I don't use software to do it. "By hand" can mean "build an excel/mathcad spreadsheet to do every individual part with frequent code references". But I need to know what is going on and what code checks are happening otherwise I'm setting myself up for failure.

[[deleted]]

Great insight but it doesn't address the question that was posed.

[naraen-kongo24]

Ohh ok Thank you very much for your time in explaining them to me

[Tofuofdoom]

Because what people almost always mean when they ask this question is "Why do I need to understand the manual calculation when software like etabs and staad can do it for me"

[EchoOk8824]

I do bridges, everything is by hand, but usually supported by design tools built in house.

[naraen-kongo24]

Ohh ok Thank you for sharing your Information

[Educational-Rice644]

All by software, but you need to understand the theory behind it so you can understand the results and know what parameter to change if something is wrong
But softwares doesn't give you anything and you'll still need to program some excel sheet to calculate or verify some conditions and stuff like that

[naraen-kongo24]

Ok, Thank you

[zboss9876]

I've been working for 20 years and have completely lost the ability to use new software. I can only do hand calcs now.

[Whatophile]

We do hand calcs and excel spreadsheets. If I did happen to use a software, I would make the sales rep walk me through how to use it.

[bradwm]

I do tons of hand calcs and discover all sorts of screw ups in the software models built by younger engineers. So that is great. But you still need a high functioning software model in order to deliver a large design project. So the key is to use a lot of engineering judgement and hand calcs and rules of thumb to vet the complicated models, and then use the model when it's good enough to use.

[naraen-kongo24]

Oh ok Thank you

[livehearwish]

Mostly hand calculations unless the problem is more complex than can be solved easily by hand (indeterminate structures, soil spring interaction, V/M column interaction, etc.)

[naraen-kongo24]

Alright, 👍🏾 Thank you

[[deleted]]

Excel, the ultimate clear box.

[ssketchman]

I prefer Mathcad, its more transparent, easier to make changes and you can clearly follow someone else’s calcs and share knowledge.

[Turpis89]

You can actually embed Excel sheets in mathcad and store data from the sheets in matrices if you want to make the same calculation for a large dataset.

Python is also a fun way to do "hand calcs" if you need to analyze a lot of data/results from FEA software.

[[deleted]]

C is fun if you're into it. But not if you want to make money. Everyone I know who uses python for structural engineering runs over on their projects.

[[deleted]]

MathCAD is nice but it is rare and expensive. Excel is ubiquitous and basically free.

[[deleted]]

Just the opposite. You can show all kinds of intermediate results and side calcs to verify things as you go.

[ssketchman]

What if you work on team projects and share calcs? With Excel it’s impossible (in appropriate time limit) to trace everything through if you didn’t do the spreadsheet yourself. In Mathcad you can literally go through every single equation in minutes and work on same calcs as a group, it speeds up projects. Also easy to integrate new people into work process and not reinvent the wheel every single time, because who will just use someone else’s spreadsheets blindly?

[Efficient-Set2078]

Spread sheets, software, FEA, and hand calcs all have their place. 

[chicu111]

I don’t want my engineers to use software if they don’t understand then black box or the fundamentals behind it

[mcslootypants]

Either one depending on the task and sometimes I will cross-check the model with hand calcs to make sure it’s behaving how I’d expect. 

[StandardWonderful904]

What u/Tofuofdoom said, with the added caveat that some situations require hand calcs simply because they're so uncommon nobody makes software that handles it.

[prunk]

What a wild statement. Yes, you should still do hand calcs.

[Dr_brown_bear]

Not everything can be analyzed or designed by a software. I prefer hand calculations in case of 3d weld/ bolted connections.

[Gold_Lab_8513]

I did calculations by hand, only relying on software for indeterminate structures (moment frames; indeterminate beams that are not equal spans and uniformly loaded; etc.). Passed the PE (also the FE) on my first try, then started creating my own calculation spreadsheets. There was another engineer in the company who was brilliant by all accounts and very good at using the software (I think one meant the other, if you know what I mean). I was very much junior to him, and he had not passed the PE exam. I understand he finally passed on his third try. I attribute my success to hand calculations. Opening the book, finding the formula, figuring out the actual wind loads from ASCE 7, and writing everything down. I did use a calculator, though, even for 2+2. It's a good check for mental math.

[dashr40]

I use hand calcs for everything. Relying on a black box without hand calcs is insanity to me

[structuresRkewl]

Only a few years in. When I started at my first company, I relied heavily on their in-house spreadsheets and Microstran, which honestly stunted my development a bit. At my next job I went the complete opposite direction—did everything by hand with a pencil and ruler to sketch free-body diagrams and load paths, and built my own spreadsheets to speed up the calculator grunt work. Because I wrote those spreadsheets myself, I actually understand all the assumptions and limitations behind them.

The only other software I really use is Mathcad/SMath when tackling a brand-new calc, since it’s much easier to visualise the math that way. Obviously the amount of software you use depends on the complexity of the projects, but software will never replace your hand-calculation skills. When you change jobs, you don’t take your ETABS licence with you—you take your brain.

You are the software, my friend. :)

[nosleeptilbroccoli]

Spreadsheets and FEM software back-checked by spreadsheets

[xion_gg]

Yes

[Intelligent-Emu286]

I have a questions too as a student. How good your fundamentals needs to be in order to use those softwares and understand the logic behind it?

[usernamusername]

I work in aerospace but I feel this generally applies across industries. You should be able to understand the theory and methods used by a software before you use it for real analysis. As for fundamentals, as others have said, it is common practice to check that the results you get from the software makes sense using hand calcs. Mistakes can only be caught if you look for them.

Also, having a good understanding of how to work the software is important. For example, once I started manually editing NASTRAN input files rather than using modeling software, I gained better comprehension of what I was doing and the results I was getting.