3 ms·

In Canada we use what is called limit states design and it handles the sudden failure vs gradual failure already. Essentially if you want to use a member or a m

In Canada we use what is called limit states design and it handles the sudden failure vs gradual failure already. Essentially if you want to use a member or a material that suddenly fails you must design it to fail one tenth as often. In practice engineers go even more overboard because nobody wants blood on their hands and gradual failure greatly decreases the odds of that from happening. In terms of construction materials in condos failing (glass and piping) I actually put the blame for those two failures on the individual testing companies. Engineers in Canada don't understand statistics properly because most aren't taught materials testing properly in university. But we don't live in a utopia either. It is expected that things will go wrong sometimes and that we'll have to update our building codes to address those shortcomings. My issue with Canada is that we don't have a (or at least I'm not aware of there being a) structured materials testing code. Sure we'll regulate materials and connections for our main structural elements, but there will always be that last mile where someone will want to do something weird (like build part of the building under railway or if someone over bent some reinforcement bar and you need to authorize them rolling it back) and you're pretty much out on your own once you come to those scenarios. It's doubly unfortunate because most of the engineers that just look things up in tables are basically helpless because they don't remember or use the basics day-to-day. So they end up being extremely conservative - unnecessarily wasting money and material for all of us.

abduhl 10y ago
I don't practice in Canada, but my understanding was that the CSA is an analogue to the ASTM codes here in America (and internationally apparently, if you believe their name change). ASTM codes are very thorough when it comes to materials testing. I believe Europe has a similar standard. I don't understand how your third paragraph's thrust follows from your second paragraph - what does materials testing have to do with site specific (railway) or field changes (bent rebar)? How long did you practice in Canada? Your viewpoint of engineers meshes well with the opinion that I've heard from a lot of junior level engineers who are just making the adjustment to a mid-level position but are still interacting with the lower level staff who are, as you say, typically helpless. They are supposed to be - they are still learning.
- 3pt14159 10y ago
  Only about 3 years before I got fed up and left. I'll fully admit I didn't get that involved with materials testing; and perhaps the firm I was with was substandard in this regard; but I don't think so. When I looked into the falling glass in Toronto I learned that they only tested a very small number of fasteners. I don't recall the number, but it was trivial statistics to prove that for the number of glass panes going up in Toronto they didn't have a large enough "n". The two examples I gave were two examples that I dealt with personally. I was extremely dismayed at the rigour the firm I was at used. To test the bent rebar I think we used a sample size of 6 and then tested to failure. For the railways example they just used the weight of the train. Then when I reviewed the designs and brought up that the train could apply the breaks and thereby increase the downward force they just multiplied everything by 2. In my experience the low level staff was useless, with a couple people that knew what they were doing. The medium level staff had two groups of people, the people that still knew advanced math and the people that got good at AutoCAD, and the senior people, while good at sales or general guidance; had basically completely forgotten all but the most basic structural engineering principles. I've literally had to explain crushing vs bending moment to a 20 year structural engineer before. I've (accidentally) designed a structure that was already designed by a senior person that forgot to put it in the tracking system. I used one sixth the steel and mine could handle more load. I will grant you, however, that I may have just been at a substandard firm. We had some large projects, but we weren't designing new skyscrapers or mega-structures.
  - abduhl 10y ago
    For someone who is self-admittedly not knowledgeable about the testing requirements, you seem very certain of your conclusions about this Toronto falling glass problem. Testing of components is usually by the manufacturer and it is their responsibility to provide a product that meets the requirements of the design. This is not a problem from the design side and is very difficult to prevent without the engineer being onerous with his requirements to a point that no engineer is really willing to go to. I'm not familiar with the specifics of your rebar example so I can't comment. Your example with the train makes no sense - the design loading for railway is codified in the design manual (AREMA in the USA) and includes dynamic forces. Braking forces are applied longitudinally to the track so unless you were in a curve there is no downward force. I find it hard to believe that your boss agreed with a fictitious force and then just multiplied everything by 2 to get around it. Your opinion on your colleagues is concerning to me and is probably more indicative of your lack of experience than the other staff's incompetence. Your experience reads like someone suffering from 200th hour syndrome, I wouldn't be surprised that if you stuck with it another 3 years you would have realized your initial impressions were way off base. At worst, it sounds like you may have been working at a firm that did commodity work and didn't attract top tier talent. If you are as good as you seem to think you are then you should have jumped ship when you got "fed up". I don't intend for this post to sound dismissive but it will probably come off that way. As an aside, knowledge of advanced math is not necessary for structural engineering in my opinion, nor is it common.

abduhl 10y ago

I don't practice in Canada, but my understanding was that the CSA is an analogue to the ASTM codes here in America (and internationally apparently, if you believe their name change). ASTM codes are very thorough when it comes to materials testing. I believe Europe has a similar standard. I don't understand how your third paragraph's thrust follows from your second paragraph - what does materials testing have to do with site specific (railway) or field changes (bent rebar)? How long did you practice in Canada? Your viewpoint of engineers meshes well with the opinion that I've heard from a lot of junior level engineers who are just making the adjustment to a mid-level position but are still interacting with the lower level staff who are, as you say, typically helpless. They are supposed to be - they are still learning.

3pt14159 10y ago
Only about 3 years before I got fed up and left. I'll fully admit I didn't get that involved with materials testing; and perhaps the firm I was with was substandard in this regard; but I don't think so. When I looked into the falling glass in Toronto I learned that they only tested a very small number of fasteners. I don't recall the number, but it was trivial statistics to prove that for the number of glass panes going up in Toronto they didn't have a large enough "n". The two examples I gave were two examples that I dealt with personally. I was extremely dismayed at the rigour the firm I was at used. To test the bent rebar I think we used a sample size of 6 and then tested to failure. For the railways example they just used the weight of the train. Then when I reviewed the designs and brought up that the train could apply the breaks and thereby increase the downward force they just multiplied everything by 2. In my experience the low level staff was useless, with a couple people that knew what they were doing. The medium level staff had two groups of people, the people that still knew advanced math and the people that got good at AutoCAD, and the senior people, while good at sales or general guidance; had basically completely forgotten all but the most basic structural engineering principles. I've literally had to explain crushing vs bending moment to a 20 year structural engineer before. I've (accidentally) designed a structure that was already designed by a senior person that forgot to put it in the tracking system. I used one sixth the steel and mine could handle more load. I will grant you, however, that I may have just been at a substandard firm. We had some large projects, but we weren't designing new skyscrapers or mega-structures.
- abduhl 10y ago
  For someone who is self-admittedly not knowledgeable about the testing requirements, you seem very certain of your conclusions about this Toronto falling glass problem. Testing of components is usually by the manufacturer and it is their responsibility to provide a product that meets the requirements of the design. This is not a problem from the design side and is very difficult to prevent without the engineer being onerous with his requirements to a point that no engineer is really willing to go to. I'm not familiar with the specifics of your rebar example so I can't comment. Your example with the train makes no sense - the design loading for railway is codified in the design manual (AREMA in the USA) and includes dynamic forces. Braking forces are applied longitudinally to the track so unless you were in a curve there is no downward force. I find it hard to believe that your boss agreed with a fictitious force and then just multiplied everything by 2 to get around it. Your opinion on your colleagues is concerning to me and is probably more indicative of your lack of experience than the other staff's incompetence. Your experience reads like someone suffering from 200th hour syndrome, I wouldn't be surprised that if you stuck with it another 3 years you would have realized your initial impressions were way off base. At worst, it sounds like you may have been working at a firm that did commodity work and didn't attract top tier talent. If you are as good as you seem to think you are then you should have jumped ship when you got "fed up". I don't intend for this post to sound dismissive but it will probably come off that way. As an aside, knowledge of advanced math is not necessary for structural engineering in my opinion, nor is it common.