Sunday, August 04, 2013

I've mentioned before my opinion that a good teacher

is a treasure to be cherished*; just had another example of that.

Speaking to a guy who's an engineer who brought up post-tensioned concrete construction, and since I'd heard of it but knew nothing I asked for details.  It seems that using that method isn't actually taught in school("There are EXPERTS who will do that", etc.).

One of the first jobs at the company he worked for, guess what  the project he was assigned to used?

About oh-dark-thirty he and three other guys were sitting in the office trying to figure out how to make the specs they'd been given work, and it wasn't working no matter how they tweaked it, and they were accelerating down the ramp to screaming when one of the owners walked in("Just dropped by on my way home", which was BS because home was in the other direction from the airport), stopped in the door and asked what were they doing there?

"Trying to make 'X' work."

Heavy sigh.  Slow shake of head.  "Guys, it's not that difficult."  Took a legal pad and, in half-an-hour on ONE SHEET, gave a college-level class on post-tension concrete construction that had all of them saying "Well, shit, it's not hard NOW."

He'd saved that sheet.  And had, a couple of months before we met, used it to clear up the same mysteries for a new engineer with the company working under him(apparently it's STILL not taught).

That owner had been a professor of engineering; and I'll bet the students who came in after he left never knew what they missed.  And probably never had someone who could do what he did.

*The followon is 'and bad teachers need to be thrown the hell out before they do more damage than they already have.'  Which really pisses off the 'All teachers are wonderful!' idiots.


Alien said...

Purely selfish on my part, but if you have access to that sheet it would be terrific if you could scan it and post it. I've got a project that can be accomplished in other ways, but I've wondered if post-tensioning might make it easier to do and produce a better result, and like everyone else, I need to learn a lot more about post-tensioning.

Firehand said...

Alas, I do not; this was a conversation between two people who happened to meet.

This makes me wonder: is the system so complicated that "You engineers need to leave it to the experts", or is it a case of most teachers don't understand/can't teach it, so that's the easy way out?

Meghan @ Laugh Lines and Love Letters said...

Try one of these references:

Prestressed Concrete: A Fundamental Approach by Nawy (ISBN 9780136081500)

or PCI Design Handbook, Precast and Prestressed Concrete

Both are excellent references and should be able to shed light on the details of both pre-tensioning and post-tensioning. In a nutshell, it has a lot to do with moment distribution along the member. As for the idea of "leaving it to the experts", the topic of prestressed concrete is generally a higher level course, offered/required at the Master's and PhD degree levels. As becomes obvious in many undergraduate disciplines, the typical 120 hour Bachelor's degree curriculum has so many requirements that it can be difficult to delve into the details of all aspects of that subject area (hence the need for continuing education, and the growing need/acceptance/push toward post-baccalaureate studies). In civil engineering, it is typical of an undergraduate curriculum to require a course in reinforced concrete, but to leave "advanced" concrete design to only those interested in that particular subject area.