The trade of the structures consultant (III) | Juan Carlos Arroyo

Does how much weigh his building?

La torre Eiffel: la construcción de un coloso, febrero de 1888 | Fuente: National Geographic
The Eiffel Tower: the construction of a Colossus, February, 1888 | Source: National Geographic

We all think that our profession is many responsibility. The consultants of structures also … why not!

The professionals we have a responsibility on the result and therefore we must know what has to give, before doing the work. We have to have this fusible alert in order that if it works out slightly rare, we say be careful!

What would happen if your consultant of structures was confusing the kilonewtons and the tons? Would you award the project of the structure?

Already I postulated that the good professional, in my opinion, consists of three ingredients, recordémoslo clear concepts, order of magnitude and knowledge of the technology. Of the first one, of the concept, already we have spoken previously, because of it in this occasion centre to the second one of them: the order of magnitude.

Can you be possible a good professional without having order of magnitude?

It there can be no good professional if it does not know all the values and coefficients involved in his daily work.

The farmer of an estate of oranges must know how much costs a kilo of oranges and how much they cost hundred (eye let’s remember that the price is in the habit of being a not linear function!) and how much costs the transport up to the store and when it is the best date of withdrawal and how many oranges are gathered from an orange tree and the orange trees that they fit in a hectare and what is a hectare do you imagine that a farmer does not know how many orange trees it has or what surface of plantation it occupies …?

And you, architects, engineers … have you order of magnitude?

In PFC’s courts my pupils know that always they fall these questions:

– CanMr. Fernandez say to me, how much cost his building?

– How many square meters it has?

– What price is he constructing?

Buckminster Fuller, uno de los protagonistas de este post, delante de una de sus cúpulas geodésicas | Fuente: arquine
Buckminster Fuller, is the one of the protogonists of this post, in front of one his geodesic domes | Source: arquine

Many of them they do not know it! Well, they are students … you it yes know it… Or you should not? Your work and ours is of a tremendous responsibility therefore we will have to have in the head all the relevant information.

Remember that there is an effect derived from the authorship that is the responsibility of everything all that is signed. The author must know his work as nobody, at least up to a certain level of detail, that the judge is not going to allow him to be a minimal level.

Other one asks, that also I use very much in the PFC, I her copied Mister

Say me, Norman,  how much weigh your building?…

El oficio del consultor de estructuras (III) Juan Carlos Arroyo Norman Foster
Norman Foster

What good it had remained Foster with his friend Fuller! But it did not know it, and the response is easy well, an empty building weighs half a ton per square and full meter, a ton. So … so many square meters so many tons.

An author has to know how much weighs his work, an engineer of SEAT must know how much weighs his car, does not make a taxi driver lacking him, though there is sure that it knows it. An architect, the author of a building, has to know it to decide what foundation he needs, to value the sustainability of his construction, to criticize it if it weighs very much for aesthetics!

But better, we continue doing inconvinient questions. We all know what is a kilo, but we know what is a newton?

It is worth neither looking in Wikipedia, nor doing accounts of F=mg; it is necessary to know it since you know the name of your son without winking! A kilo we know what is, have born and grown with kilos (actually we say kilo and we should say kilopondio, thousand units of force of the system CGS), but a newton

A newton they are hundred grams, and in order that one does not forget us we must associate it with something known, hundred grams it is the unit of measure of the charcutero, “give me two newtons of salami” it is the new one “give me two hundred grams of salami”.

A pupil, one day, gave to me a much more poetical response:

– Teacher, a newton is an apple (drawing).

– To your feet!

En la charcutería Newton el embutido se pide en newtons | Viñeta de Ed Marks
In the deli the sausage itself asks for Newton in newtons | Ed Marks´s emblem

It can only for clarifying another very interesting matter related to the order of magnitude, that it is the precision. It will be in the next post.

And I leave a few worrying questions you to answer on your current or next project:

– How many shoes it has his building?

-And how many props?

– What length has it? Does he need together?

– How much is m2 of forged?

– How many kilos of acero/m2?

– Why did you choose this structure?

– Has it made something you to relieve the active arrow that fisuró the partitions?

– Has it done something to guarantee the intraslacionalidad?

– How does it resist the horizontal effects of wind?

If you are the author of the structure, you must know it, the judge like that is going to consider it.

He remembers, there is no money to pay a structural failure, at least this humble consultant of structures.

Juan Carlos Arroyo ( and CALTER engineering) doctor civil engineer.
Madrid, August 2017

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