The Thrill of Conformity

by Don Friedman on March 14, 2019

It’s not often that obscure engineering criteria make it to the op-ed page of the New York Times, but it happened recently with regard to “concrete masonry units” also known as CMU also known as concrete block. “The Joy of Standards” by Andrew Russell and Lee Vinsel is about the way that modern technological system work better because of standards. Their piece does a nice job describing why standards matter; rather than repeat to all here, I suggest simply following the link above.

They discuss the use of CMU as described in TMS 402 – the national masonry code put out by The Masonry Society – and the role of the American National Standards Institute. We deal with TMS when we design and analyze masonry, but ANSI is more focussed on machinery than on structure. It’s worth taking a look at the multiple levels of standards that we rely on and are constrained by.

At the top is are the local building codes, which are laws passed by cities, states, or other local governments. They provide standards for that locality. So, for example, New York has somewhat stricter laws regarding fire ratings than most of the country because (a) it’s logical to do so in a dense city with a lot of high rises and a lot of old buildings with wood framing and (b) we have had horrendous experiences with fires. Just about any part of a local code can vary from one place to another, but most don’t. So this is standardization at the local level.

Below that is the International Building Code, which is a generic US code (despite the name) that serves as the basis for the local codes. A city or state could simply adopt the IBC as is, with zero changes from the generic template, but few do. Even with the local changes, the presence of the IBC as the basis for the local codes provides some national standardization. When I look at the local code in a place I don’t often work – as I recently looked at Virginia’s code – it mostly looks familiar.

Below that are the specialized national-standard codes that are the basis for the IBC. TMS 402 for masonry, AISC 360 for structural steel, ACI 318 for reinforced concrete, ASCE 7 for loads, and so on. (Yes, there is a pattern to those names; yes, it is a quite geeky pattern.)  And that’s just the structural portion of the code: there are similar national standards in other design fields.

At the bottom are the basic standards for materials. Most of these standards in structure come from the American Society for Testing and Materials. So, for example, the type of steel commonly used for structural angles is designated as ASTM A36. The “A” series of ASTM specifications refers to ferrous metals, and some of the standards are quite old. ASTM A6 provides the geometry for most steel shapes, which is the most basic form of standardization imaginable: if I’m going to specify a beam, I have to know that the size is independent of the manufacturer, or else I’d have to specify the manufacturer and not just the size. That’s not speculation, but rather the situation that existed until 1896, when the American Association of Steel Manufacturers created the “American Standard,” which was the first national standard for steel shapes. The illustration above shows some American Standard sections.

And, as Russell and Vinsel discuss, having all of these standards doesn’t really constrain design. Rather, it allows us to concentrate on the interesting and challenging parts of design because we don’t have to spend our time worrying about whether nuts from one factory will fit on bolts from another.



A Constellation

March 10, 2019

The NYC Department of Buildings has released another on-line tool. This one provides a fast summary of permits, complaints, inspections by the DoB, violations, and construction accidents for every building in the city, accessible by a map. If you click on the screenshot above, you’ve got the entire city, as I zoomed way out. I […]

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Gotta Start Somewhere

February 20, 2019

The picture above is the answer to a question that people outside the field rarely think about: how do you know where your building actually is? There are two common ways of thinking about location: using a map (at any scale, up to maps that are detailed to the inch like Sanborn Fire maps) or […]

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A Difference Between Structural and Systems Technology

February 19, 2019

That’s a picture I took in a church attic some time ago. The wood members in deep shadow are the purlins and plank deck of the roof, and are fairly ordinary structure for a building constructed circa 1900. The brightly-lit piece of wood is a support for the electric wiring, and the wiring is of […]

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Good Recommendations

February 2, 2019

Joel Moskowitz’s list of books on furniture and woodworking is great. Every one is a classic worthy of your time. Moskowitz took the words out of my mouth with regard to Eric Sloane’s A Museum of Early American Tools: I read and reread that book when I was a tween until I had it memorized. […]

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Follow-up on Economics and Metal Fabrication

January 29, 2019

Bill Harvey sent me this close-up after our sight-seeing trip to the Clifton Bridge.* Putting aside the beauty of the photo in itself, it has something to say about changes in metal (in this case wrought iron) technology over the years. That’s a connection between two parts of an iron tie in the vaults at […]

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A Work-Around

January 17, 2019

I was fortunate enough last week to be taken on a tour by Bill Harvey of some of the engineering sights of western England. I’ll be putting up a few of the photos I took between now and the end of next week…starting with the picture above, of the front of the Corn Exchange in […]

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Stylistic Differences And Technology

January 16, 2019

That’s Buckhill Lodge, a private house located within Kensington Gardens in London. As I approached it and took this picture, I was surprised and thinking that carpenter’s gothic wasn’t really an English style. Then when I got closer, I realized that I had made a category error by making an assumption. Here’s the trim on […]

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Book Review: The Shock of the Old

December 26, 2018

The most interesting non-fiction books I read have something in common with the most interesting project we get in the office: they fall in between usual categories in a manner that requires thinking in more than one discipline at a time. The Shock of the Old by David Edgerton is a book on the history […]

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Incredible And Maybe Useful

October 17, 2018

Microsoft developed a database of building footprints across the country using satellite date, and the New York Times turned it into a map showing, more or less, every building in the country. Click on the link and you can enter a zip code to find your house, zoom in, and pan around. It’s a weird […]

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