Codes and standards VS. Innovation:
I agree with Donald that codes and standards are not to be taken lightly. They sum past collective experience and they are the result of massive research and safety factors calibration. The later is based on target safety vs. cost as determined by several parties, most of which are not engineers. "target beta" that determines the risk factor is agreed on in advance within financial limitations. (Pyramids of Egypt last for ever, but at what cost?). Based on that + surveys of past performances, code calibrators come with the factors of safety that we find in codes and standards.
That becomes the law. You are not allowed to cross a red light even if there were no other cars at the intersection. And you need to defend yourself in case of legal challenge. That could be due to others' mistake, yet every one involved in the project becomes a suspect. If you count on your scientific proof, good luck; the other parties can hire other engineers to write a contrarian opinion. Only if your design fulfills the code you can defend yourself. I'm talking from my experience as an "expert witness".
Within the above limitations we do our innovations. If we feel the limitations are out of touch with new reality, then we can join code committees to propose alterations. For example, in our Precast concrete industry, concrete is under higher plant quality control than on site. So, we proposed increasing the phi factor from 0.60 to 0.65, thus reducing the overall factor of safety by 8%, a small but deserved win for that industry. Another example: water pressure in underground structures, is now allowed in some codes, to be based on pore water pressure rather than static water pressure. Pore water pressure takes into consideration the dynamic flow of water, which reduces pressure substantially; however recalibration of overload factor is needed. Another example: our transit team in Toronto introduced soil-structure integrated design, where soil is part of 3-D finite- element structural model. Soil resistance helps the structure against imbalanced lateral loads, reducing structural cost substantially. That needed a lot of convincing, before it became a reality. Prior to bringing it to Canada, we convinced the National Transit Authority of an oversees country to adapt it. They changed their NTA's code accordingly. When applied to the whole transit program for the country, the savings run in hundreds of millions of dollars.
Very much as we do in life in general: we work within the law, but we also work on adapting the law to new realities.
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Neil Kazen, M.Eng., M.Sc., P.Eng.
FASCE, FCPCI, FEC,
Retired Structural Engineering Manager, Transportation Division, SNC-Lavalin
Toronto, Ontario, Canada
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Original Message:
Sent: 05-09-2019 13:52
From: Donald Stursma
Subject: Engineering Judgment
Responding to this and other postings on the role of codes and standards.
Codes and standards represent the collective consensus wisdom of generations of engineers, so are not to be taken lightly. On the other hand, they may become cookbooks leaving little room for innovation or alternatives.
The ones I have worked with were generally minimum standards, where the engineer is free to be more conservative if deemed necessary. However, you may need to convince clients or regulatory agencies that any additional costs incurred are justified.
If it is believed a standard is unduly conservative or restrictive it's a little harder. Sometimes a standards organization, or a regulatory agency that has adopted the standard, will have a waiver or variance process, typically requiring a showing that the alternative proposed will provide an equivalent or better level of safety than what's in the standard. This of course takes time. You may also need to run code departures past your liability insurance carrier.
Joining a standards organization and working within it to improve the code can also be an option, but that will take time so is not a near term solution.
Will let others address whether modelling programs have the codes built into them to the point that modelling alternatives becomes difficult.
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Donald Stursma P.E.,M.ASCE
Manager
Pella IA
(641)621-1613
Original Message:
Sent: 05-08-2019 13:11
From: Dilip Barua
Subject: Engineering Judgment
The question of judgment, and the role of standards and codes in engineering came into the discussions again and again. This is a great topic that defines an engineer and we all want to have a clear understanding of it. Amid many thoughtful discussions, here is my further take on this.
First, let me start with semantics of judgment. Webster: the process of forming an opinion or evaluation by discerning and comparing . . . Oxford: a decision or opinion about someone or something that one forms after thinking carefully . . . Both the definitions rely on the word, opinion (an opinion is a viewpoint or statement that is not conclusive). In other words, opinion is different from fact, and is seen as subjective or biased because it could be colored by a person's perspective. The second part of the definitions, however clarifies and qualifies opinion by saying: . . . evaluation by discerning and comparing . . . or formed after thinking carefully. . . All these qualifiers are indicators of rationality that are enriched by an engineer's experience – in a way to minimize inconclusiveness or uncertainty. And senior professionals are the ideal candidates to pass that on to the juniors.
I have attached an academic paper that talks about engineering judgment in connection with foundation design. It highlights that engineering judgment is an evolving process – enriched with experience and precedents, to the statistics based reliability design (not a mainstream pursuit yet).
Standards and codes are an important guide, required as a minimum during the design process. Their role is crucial during the conceptual designs (when many parameters are unknown) – but could inhibit creativity and innovation if overly relied on. The reason is that these documents provide some blanket requirements which may or may not represent actual field conditions (that is why consultancy is justified anyway). And they always come with disclaimers. The British Standard (BS 6349-1:2000. Maritime Structures – Part 1: Code of Practice for general criteria) says: This code of practice contains information and guidance for . . . Engineering judgement should therefore be applied to determine when the recommendations of the code should be followed and when they should not . . . This code of practice is intended for use by engineers who have some knowledge of the subject. . .
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Dr. Dilip Barua, Ph.D, P.Eng, M. ASCE
Vancouver, BC, Canada
Website: https://widecanvas.weebly.com
Original Message:
Sent: 05-08-2019 00:44
From: David Thompson
Subject: Engineering Judgment
I am going to try to deal with the questions; how do we gain engineering judgement and is engineering a science or an art?
One of the most interesting reads I had, was a text book (yes a text book) that I picked up in England called the "Art of Structural Engineering". One of the books main points was unlike other professions Engineers are trained to look at details. One of the dangers of focusing on details, was the engineer would loose sight of the overall project. (You can not see the forest because of the trees) On some projects coming up for air and looking at the overall project gives a better solution. Yes there is more Art in the Science of Engineering than we care to admit. If you doubt this look at how many musicians are also engineers. Engineers like to be creative despite of our reputation in University.
I found my curiosity about things helped in learning how loads, materials and structures behaved. One of the questions I have asked staff is after they analyze a structure is not "what is the answer", but, "tell me the story that the analysis showed you, how does the structure work, does it make sense?" This approach gave me a better understanding and a foundation for "judgement" Experience not only doing engineering but other things like construction or sales helps. You gain the judgement of how to deal with people's anxiety. If you attempt to build something that is too complicated, it is likely you won't design in that manner later. Or from construction you find that you can do things that material standards say is impossible. I found that to be the case with wobble and friction values in post tensioning of concrete.
However, you will find engineering judgement when you go back and check your decisions is based on solid mathematics that you have done earlier in your career.
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David Thompson M.ASCE
Principal
KTA Structural Engineers Ltd.
Calgary AB
(403) 246-8827
Original Message:
Sent: 05-07-2019 21:09
From: Mitchell Winkler
Subject: Engineering Judgment
I find the questions asked in this thread thought provoking and responses very thoughtful. At the end of the day, I see our job as engineers as being able to deliver a desired functionality or outcome while managing risk - though elimination or mitigation to acceptable levels. For me, engineering judgement is a tool in the tool kit along with analysis techniques and design equations to manage risk. Finally, I see engineering judgement as spectrum of capability, e.g., one end being able to ask the right, and sometimes difficult, questions, while the other end being able to modify practice or outcomes where guidance is absent or ambiguous. I suspect engineering judgement will become increasingly important with climatic change upon us and imprudence to rely on the past as a predictor of the future.
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Mitchell Winkler R.Eng,M.ASCE
Houston TX
Original Message:
Sent: 04-30-2019 21:47
From: Kim de Rubertis
Subject: Engineering Judgment
As engineers we find safety in numbers, but numbers alone are not sufficient in evaluating safety and conveying risk to the public. As engineers we make judgments about safety relying upon estimates of safety factors for loading and likely responses. Engineering judgment provides the check on the numbers we use to quantify safety. I explain this concept in more detail in the attached document.
How do we go beyond the numbers and use engineering judgement to protect the public we serve?
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Kim de Rubertis P.E.,CEG,D.GE,F.ASCE
Consulting Engineer
Cashmere WA
(509) 782-3434
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