No confidence in design 13

[PEinVA]

Guys,
Over the last 2 months or so I've had a few times when thinking about designs I've done, about how people could easily die or get seriously hurt, that I've almost given myself a panic attack. I've just had serious doubts about my work and designs and I comfort myself by doing some reviews, etc.

I don't want to suffer like this.

Any help from the older guys?

RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[swearingen]

You should not be having these sweats yet. You are not a Professional Engineer. My designer gets aggravated when he misses something, but it does not keep him up at night. However, now that I've been stamping designs for years, I can recall a few times that I've sat bolt upright in bed running calcs through my head.

You should do the best you can and review it with your peers, but ultimately the sweats belong to the person whose name is on the stamp...



If you "heard" it on the internet, it's guilty until proven innocent. - DCS

 

[csd72]

I used to be worried about these things but now I am just more dilligent.

A Professional engineer should not expect someone with 2 years experience to get everything right so if they dont check sufficiently that is their fault.

That said there are things that you can do to minimise mistakes. Get into a sequential procedure when you design things and double check as you go along. Start with the loads then double check them and move on from there.

Also you should always try to keep the design as simple as possible, a simpler design is generally quicker and easier to build and will be easier to quality control.

Don't worry too much about your design mistakes, it usually requires more than 1 serious mistake before it truly becomes dangerous. There are almost always alternate load paths.

 

[PEinVA]

I guess I don't necessarily mean no confidence in my design but rather a lack of certainty, mostly cause I'm relatively new. I guess time will help most.

Thanks to everyone who has responded particularly the structural guys who I'm sure have more of an understanding of what I mean.

To the guy who suggested I see someone about anxiety issues, it is not anxiety due to am I going to step on lines on a floor today (As Good As It Gets) but if something I designed is going to kill/hurt/endanger someone. I'd ask you to get some professional help if you believe there is something wrong with that concern.



RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[msquared48]

Professionally, I never design right up to the line. I always try to design in an additional margin of safety, additional load paths wherever I can, as mistakes can be made by anyone. This approach has saved my a#@ and that of the contractor on more than one occasion, proving the structure stable with a more sophisticated analysis.

This method is not well suited to high-rise structures, but definitely appropriate for residential and small commercial projects.

Even after 30 years of doing this, I still sleep well at night.

Mike McCann
MMC Engineering

 

[plasgears]

In jet engine layout work, the aerodynamic flow path is considered hot; you need to convert it to cold layout in order to design your parts.

I had a boiler plate afterburner test rig that was bolted together rather than carefully welded in near flight weight configuration. I made the mistake of using the hot layout as the working cold layout. Did it make a difference?

On test the articulated flap links for the variable nozzle collapsed, and the rig came back to the factory. I added spacer blocks to make up the difference, and it worked later on test.

My next assignment was in another section of the engine. I worked my way forward to the fan by the time it was all over - ten years later.

 

[Gymmeh]

My first job, I was always stress out, I was one year out of school designing cranes... and realized the engineer i was working with was completely incompetent and made gross errors and never really checked my work. Two of his cranes failed their proof test!

Now the probability of me killing anyone is nothing because I did everything buy the book and to code, there are nice safety factors, and cranes are (or should be) regularly tested. Along with this I studied the regs/codes at night after work. I can sleep because of this.

I quit this job because of the negligence of all the people around me, their lack of understanding for engineering, and their inability to consider change.


If the people around you are competent talk to them and let them know your concerns.

If the organization as a whole has major issues. Do everything to the book, trust the safety measures most industries have, get another job.

PS:my wife and friends like that I am not stressed out jerk all the time.


Official DIPPED Member -
Drank in PP Every Day

 

[csd72]

RCraine,

I think I understand where you are coming from.

I used to worry a bit at your stage. The problem is that most graduates get thrown in the deep end without being told the 'correct' way to design a whole building.

You either sink or you learn to swim, It wasnt until I started at a company after 7 years experience that someone actually sat me down and explained how they actually designed a building.

This increased my confidence dramatically as there was always the small doubt before that I was not doing it the correct way.

At 2 years experience, do not be afraid to ask lots of questions this is to be expected and is the best way to learn.

 

[whyun]

Having doubts, in structural engineering, is a good thing as in thinking of all the possible ways a system/member/joint could fail. By checking ALL of the failure modes, in due time, one gains confidence in predicting the failure modes that govern.

It is a shame that many new graduates are not given the proper mentoring and training, most likely due to laziness/ineptness of the senior guys in their firm. Early in the career, it is extremely important to meet a good mentor that you will remember for the rest of your career.

 

[s0eebuch]

Years ago, I was a boiler start-up engineer and we were installing a boiler that was right at the line in pressure/temperature for the manhole cover gaskets that we were using. By "right at the line" I mean it was close, but deemed acceptable by our design engineer.

Well, during startup, as the temperature gauges started to creep up to the operating point, the steam drum gasket blew. And I mean BLEW. It could have seriously hurt someone.

I went back to the specifications for the original gaskets and decided to spec the next temp/press range gasket, which happened to be rather expensive. Even after the incident during the initial startup, our bean-counters were still up in arms over the increased cost.

....I still shiver at the memory of what could have happened...

The worst part of this was that I felt something was not right (designing that close to the limitations of the gaskets - S.F. of 1, essentially) but didn't challenge the design engineer becuase I was so new.

Never be afraid to ask the question if you aren't sure - even if you think it'll make you look bad.

Makes for a much safer design and allows one to sleep at night.

 

[mauricestoker]

I can sympathize with what you are going through. I hope you never lose that sensation, but use it to help concentrate.
I've been responsible for biological safety design and construction, and as responder. I would rather be responsible for the design and construction than being called in at 4 AM on Christmas and wondering if I (and my friends) will be spending a few weeks in an isolation room (or worse)because someone else did not get upset because their work was crap (and they certainly paid for it, but only financially). Do not let a PE stamp assuage your concerns, look into the design, and understand why and how things work. Until you are ready, someone should be checking your work; by then, you should hopefully have the same fears, but have learned to manage them (or have a gastroenterologist on first name basis). Build on every success, and learn from your failures. I've had more stressful jobs (some of the %@#&* overseas was scary) but couldn't imagine the stress that police officers deal with pulling someone over in remote dark spots on a routine basis, a fireman responding to an industrial site, or a hooker negotiating with a lech covered with scabs). Matter of perspective; it helps to have a sense of humor. Pride in your work will pull you through; if you do not have that pride but still have the stress, find another job.
On the upside, ulcer drugs have improved greatly over 25 years. On the downside, you are young, and may one day have to deal with a teenage daughter. Then, be afraid, be very, very afraid.

 

[WhyDoYouAsk]

Two benchmarks

http://en.wikipedia.org/wiki/Reasonable_person

http://www.cnn.com/US/9909/10/ivey.memo/

 

[southard2]

A few comments and tips from a fellow structural design engineer. My first comment is that their are way way too few engineers who worry enough. I find that overconfidence is the STRUCTURAL engineer's biggest enemy.

Tips:
1) Know your limitations. Read and research the various items you are working on. This will help you in understanding where the end of your knowledge base is. Frequent study will refresh your own self knowledge of your own limitations. If you've never designed a thickened slab then study everything you can get your hands on.

2) Don't be afraid to ask questions

3) If you don't feel confident than do whatever it takes to give your mind peace. I don't mean block it out. I mean keep thinking about the problem until you are satisfied.

4) Train the architect you work for. After 12 years I'm realizing just how important it is to simplify, simplify, simplify your designs. Try 3 column sizes max. Try 5 beam sizes max for example. Minimize the amount of details a project will require. Don't be afraid to overdesign a bit. Simplification in my experience is more cost effective anyway.

5) As someone else said don't engineer down to the Nat's butt. Never use live load reductions you will need them someday believe me.

6) When you stop having those moments of panic over your designs please retire. The guys who don't make tons of mistakes all the time and are totally oblivious just how bad their designs are. After 12 years I still don't go over 2 to 3 months time without a panic over something or another. So don't stress about being stressed. Its what your paid to do.

7) If you find that you don't have enough time to adequately design your projects and make money than......
a) raise prices
b) simplify your designs
c) get out of the business

8) If the stress is ruining your life its time to work for someone else or change what you do within the engineering field.

9) I graduated in 1996. I find that the vast majority of engineers don't receive proper mentoring. Your going to have to do it yourself. Saadly this also means learning the hard way sometime. NEVER USE LIVE LOAD REDUCTION FACTORS.

10) Before you sign and seal the drawings think of collaspe failure mechanisms such as beam shear failure, column buckling, wall buckling due to axial loads, connection failure. Use a CSR between 0.5 and 0.8 for these type of failures. For example a series of bar joist are unlikely to fail. And even if you underdesign a beam for bending it most likely wouldn't fail suddenly. There would be plenty of warning signs. So worry more about beam shear failures, and beam shear connections. When in doubt place a beam or joist on top of the wall versus hanging it from the side of the wall. Don't be afraid to overdesign connections. They are cheap in terms of mass and the most likely failure point.

11) If you had a day were you felt rushed during a series of calcs or simply had a cloudy head then take another look at those calcs.

12) Before ever doing a calculation draft out the drawings and connection types. This will force you to really think through the complete load path of the wind or earthquake loads before you begin you design. Its actually easier to get things right the first time versus having to go back through your OWN calcs and make changes later.

13) Never lose your sense of curiosity

14) Sleep

15) Overdesign your columns....I can't reiterate that enough. Columns are cheap.

16) The first time you do your calculations right everything out. When checking yourself do the calculations in your head and force yourself to compute them in a different order or different way. If they still match your probably right.

17) Avoid nasty project without an adequate budget. Work with reasonable people.

18) Wait as long as possible to start the project while still making sure you can finish. Architects love to change stuff. This is another reason why it is good to work on the drafting and detailing first before beginning calculations. Over time your experience will allow you take the dwgs closer and closer to a finished static state before you start your calcs. Try to avoid having to change your own design. I find it terribly difficult because trying to remember all the small thoughts you had when you first did the design (the kinds you don't have time to write down) is much more difficult the second time.

19) Don't be afraid during construction to question your own design. In most cases a simple repair or change can be made to remedy something your nervous about without cost.

20) Aim small miss small. If during your design you are worried about thinks like checking your building shear walls for sliding, or column footings for uplift, or walls for combined tension loads and flexural loads, or designing your roof deck attachments for combined uplift and shear in the same load case then your are going a lot further than most engineers do. Not only does the aim small miss small idea apply but all the extra time you spent verifying things most other neglect or try to make up for by increasing their factor of safety means you've given yourself more time to actually become aware of a past mistake or error.

21) Here's an easy tip. As much as possible avoid interuption when performing your calcs. I find I can flush out most of my error simply by comparing one beam I've designed to one of the others I designed an hour earlier. Now if days seperate your beam design from the next beam design this will be less likely to occur. So continuity of thought is critical. I'm touching again here on the idea that having to make changes later is harder.

22) Aim for perfection with the dwgs. Make sure all info required for the contractor to build is on the plans and easily discernable. In doing this you will reduce the amount of RFI's and time and money spend during the construction phase. This will allow you do spend a larger portion of a projects budget during the design phase. This is an investment that really pays. If your drawings are done well then most of the problems during construction won't be yours but some poor contractor. I build credit with the contractors on most jobs. So if there is some minor issue that I've overlooked they will usually gladly mop up the mess for me. My experience of late however is that no matter how good I do the dwgs or how simple the contractors still find lots of ways to mess things up. Still its much easier to sleep at night when all the problems are costing someone else money and not yourself.

I could go on but its late now.

Just remember that the most important thing you can do is to be diligent. Trust your intuition. If your are nervous then likely more work and thougt is required. No matter how tired you are or how close the deadline do not lie to yourself or be deceived by these devilish notions:

A) I'm sure I checked that
B) boy that will be tough to figure....I'm sure it will be OK.
C) Its not my problem.
D) I'm over budget......
E) We've used that detail for everything I'm sure it will be OK
F) I'm pretty sure....
G) I know the answer already no need to do the calcs...
H) I will do it later
I) That structure isn't really important
J) No one else checks this so I won't either.....EHPA buildings actually require more brick ties for the brick veneer for example in many places.


One more pointer. Always do the calcs even if you know the answer. Once you start eye balling your design like the old guys do you will quickly lose touch. That roof beam that worked for that span last time for 800 ft2 will over a few years time now work for 1000 ft2. This is a major problem with connection details. I see way way too many engineers who because they've used this or that standard connection so many times before now think it is applicable all the time.

 

[swivel63]

i still have nightmares. and i think i always will. comes with the job. i sometimes put "just in case" steel, too.

LOL.

 

[Bribyk]

I think the fear is a good thing. I usually have the most trouble convincing myself that my design is adequate which forces me to analyze everything. I usually calculate things using as many different approaches as I can find/think of and try to look at similar designs to ballpark dimensions, etc... My designs are usually checked by someone I don't even know which forces me to think of all possible failure modes and produce clear/concise reports and drawings.

Screw ups are bound to happen but you learn from them and revise your designs and checking procedures. I imagine a lot of the different code requirements have come from past incidents, just try not to be the guy that adds something to the next version.

 

[mauricestoker]

I would add one more item. Just like with this forum, do not be afraid to ask other engineers. Unlike some other professions, it seems (from experience) that engineers are more willing to help each other, and hope they succeed. By the nature of the business, we build on each other's success.