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Have our design codes and standards become increasingly prescriptive over time? My hypothesis is yes, but I have not found any [quality] studies that substantiate this belief. I have been contemplating the push for additional certification in the case of structural engineers. I wonder if there's a connection between this push and the growth of a more prescriptive design environment. A hypothesis is that we have eroded the art of engineering via analysis and design software, which required a high level of prescription to be effective.
You are correct that our codes an standards have become increasingly prescriptive with time. This can readily been seen by comparing the volumes of present codes and historic one. The 1927 Uniform Buidling Code had a total of 156 pages (pages were 5" x 7") that covered all things structural including: loading, concrete, masonry, steel, wood and foundations. The code was all inclusinve - there were no references to industry standards (AISC, ACI, etc). Today, the IBC now contains nearly 400 pages of structural requirements (and commentary) in 8-1/2x11 format adn also references many industry standards, each several hundred pages in length.
Our reliance on automated tools to perform design has facilitated and enabled this, but is not the primary cause. There are several reasons for the increasing prescription of the building codes. One is that have many more structural systems available to us than we did in the 1920s. Another is that there is constant desire to design structures economically, and cut the inherent factor of safety in our designs - this requires more precise calculation of both loads and capacities. A third reason is that code-writers are constantly seeing things that one or more engineers did wrong, and immediately write rules (prescriptions) to tell other engineers not to do the same thing.
At a National Steel Constuction Conference, back in 2005, I presented a talk on code complexity entitlted "Simple but no simpler" This was a play on a comment by Albert Einstein that everything should be made as simple as possible, but not simpler. I argued that every engineer, architect and developer wants buidlings that are simplet to design and building, economical and safe . You can have any two - if you want it safe and simple, it won't be cheap- If you want it safe and cheap, it won't be simple, and if you want it simple and cheap it won't be safe. As a profession we have opted for safe and cheap.
Have our design codes and standards become increasingly prescriptive over time? My hypothesis is yes, but I have not found any [quality] studies that substantiate this belief.I have been contemplating the push for additional certification in the case of structural engineers. I wonder if there's a connection between this push and the growth of a more prescriptive design environment. A hypothesis is that we have eroded the art of engineering via analysis and design software, which required a high level of prescription to be effective.
Thank you for the insightful analysis. It is true that are good reasons for our codes and standards to become increasingly prescriptive with time. However, I also believe that as engineers, we may be losing the sense and understanding of what we do. Nonetheless, your explanation of the reasons for the increasing prescription of building codes is informative and sheds light on the complexity of balancing safety, simplicity, and cost-effectiveness in building design.
Safety is the responsibility of the engineer. A better understanding of safety elevates the profession and reinforces this responsibility. Code should enhance this understanding rather than dilute it.
Hi Ron, thanks for your insightful response. I found the article you mentioned as well as a recording of your presentation at this link. The article mentions 2008 which is close to your 2005 so I'm thinking they are one in the same. I would encourage everyone interested in this topic to read/watch.
Maybe another way of thinking what codes require. 80 years ago my father found steel design straightforward. As he said to me "you only need to remember one number and you can design anything remember 33 ksi" The desgn was done by hand calculation and slide rule. When I graduated 40 years ago what I remember being taught " Here is the differential equation to solve this steel problem, it is too difficult to solve by hand so here is the simplification in the code. These days I am now hearing " solve the differential equation, you have the technology and we want to be able to do this.". Just because we are now capable of using computers to solve these challenges, it is now considered easy by others. We have gone from one number to a paragraph to a page of code requirements. The theory was there 80 years ago but now we have the computing technology to use it. The challenge for structural engineers is now you really need to understand the theory in everyday practice.
The only question I have is, are we really that far ahead of where we were 80 years ago?
I've been doing some research into complexity associated with navigating design standards and have collected some references you might find interesting.
My opinion is that one reason 'deemed-to-satisfy' prescription-based requirements appear to be rising is because engineers and inspectors find them easier to implement and verify in most instances than an equivalent performance requirement. There are a variety of pressures from code stakeholders that generate the tension between performance and prescriptive requirements. However, evidence from other industries shows that advanced design software may push requirements towards the performance end of the spectrum. If we look at fire safety design, the current push towards performance-based methods is due software modelling is being validated as representative of fire scenarios. In fire safety, performance-based methods reduce costs, increase safety, but require more expertise to implement (the same ends that Ronald H. points to). Verifying expertise becomes increasingly important as standards shift away from prescription.
Management-based regulations, discussed by Cary Coglianese, are sometimes sensed by engineers as prescriptions. Certifications and sanctioned design processes actually fall in this regulatory space. Theoretically these give the engineer more autonomy, contingent on the engineer demonstrating an understanding of acceptable design strategies (i.e. these should enable a reduction of prescriptive requirements). However, if engineers are certified by their ability to use the code, then as an industry we are granting authority based on fluency of 'codespeak', not based on knowledge of structural phenomena, per se. This would do nothing to alleviate prescriptive requirements. Law and Spinardi have an interesting discussion of this in wake of the Grenfell Fire Tragedy. See also: "A competency framework for fire safety engineering."
As Ronald H. mentioned, the code minimums keep eking closer to that of reality's minimum, often for no one's apparent benefit. I love Fling's method with dealing with this from 1979: just show that the old way is greater than the minimum.
Bulleit, W.M., and Adams, D.K. (2011). "Philosophy of Structural Building Codes." Structures Congress 2011, Las Vegas, NV, 1067-1073.
Fling, R.S. (1979). "Using ACI 318 the Easy Way." Concrete International. Jan. 52-58.
Meacham, B.J. and van Straalen, I.J. (2017). "A socio-technical system framework for risk-informed performance-based building regulation." https://doi.org/10.1080/09613218.2017.1299525
Nethercot, D.A. (2012) "Modern Codes of Practice: What is Their Effect, Their Value and Their Cost?" Structural Engineering International, 22(2), 176-181. https://doi.org/10.2749/101686612X13291382990642
Thompson, G.N. (1947). "The Problem with Building Code Improvement." Law and Contemporary Problems, 12(1), 95-110. https://doi.org/10.2307/1190120
------------------------------Chase Rogers S.M.ASCE
University of Pittsburgh------------------------------
------------------------------Mitch Winkler P.E., M.ASCEHouston, TX------------------------------
This discussion, sparked by the broader question about the necessity for SE licensure, has been particularly insightful in how the structural engineering profession has evolved and where we find ourselves today. What's come to light is we have a highly-evolved design practice that achieves safe outcomes while minimizing owner costs through the sophistication of our design codes. This design practice has come at the expense of complexity to the code and incumbent knowledge and expertise to apply the code reliably and consistently. In a way, we have become victims of our success, and returning to a less perspective environment is probably impossible. As appealing as performance-based requirements sound, this approach would impose a difficult hurdle for project approval as it does not fit into a simple check-the-box rubric. Putting the genie back in the bottle would be hard, if not impossible. Circling back to the question of SE licensure, the driver for SE licensure for me is starting to feel more about what we are asked to do as structural engineers – safe and cheap – more than anything else. As to the question of prescribing where SE licensure is required, I wonder if the boundary is more about structure scale and loading type than the structure's type or intended use. Smaller structures can accommodate some conservatism without appreciably increasing the owner's overall cost. The cost of conservatism is less tolerable for taller and heavier buildings as the added cost is magnified many times over versus a smaller structure. As we "sharpen our pencil" to wring out conservatism, we have little room for error in achieving a safe, as we define it, design, ergo, a driver for enhanced licensure for these building types.