On Breaking Rules

Why codes and standards are not always right

In my page entitled ‘what is structure?’ I began with the following quote attributed to Picasso. 

“Learn the rules like a pro so you can break them like an artist”

I inferred from this that structure does not limit creativity, and went on to argue that structure provides a framework with which to create. From this I deduced that without structure nothing we might seek to create makes sense. In retrospect I realise that I didn’t expand on why engineers, like Picasso, can benefit from breaking the rules that govern structure. I shall try to do that in this post.

This might seem at first to be a tall order, because you might suppose that the rules of engineering are fairly arbitrary and to break them would have unwelcome consequences. To make my case I intend to make a diversion into the subject of racket sports, which I rather enjoy.

After mastering the basic strokes of any racket sport it will soon become clear that there are three possible ways to score points. The first is to hit a shot that your opponent is unable to touch; the clean winner. The second is to hit a shot that stresses their technique and causes them to miss; the forced error. This is normally achieved by making your opponent play his or her shot from an awkward position; perhaps on the run or while stretching. The third way is to hope that your opponent simply makes an unexpected mistake; the unforced error.

While the third case is random, the first two can be induced by clever tactics. Perhaps the simplest, and ultimately most successful, tactic is to maximise the distance your opponent must travel between shots. This will necessitate playing on the run, potentially hitting while stretched and eventually fatigue. 

It follows that if you receive a ball from cross court the rule is to strike back down the line, because your opponent must run the width of the court to play a return shot. Conversely, if you receive a shot from down the line the rule would be to return cross court. Again, your opponent must run the width of the court.

This tactic works really well on a novice player, however it starts to unravel when you find yourself playing another player who knows the same tactical rules that you do. He or she knows that you are going to return cross court from down the line. It follows that as soon as they have hit down the line they will start running to receive your cross court shot. Arriving early on the far side of the court they will quickly turn the tables, by making you run down the other line.

To outmanoeuvre your opponent, and thereby avoid the tables being turned, you must break the rules and hit back down the line from which you received the ball. Your opponent, having set off in the other direction, must turn and run back in the direction from which they came. He or she now finds their technique being stressed again.

Now the rules have changed and you are doing exactly what you learned not to do. This, however, does not negate the rule. If you continue to return in this fashion your opponent will ruthlessly exploit your apparent naivety, as if you did not know the tactical rules to begin with.

The trick is therefore to apply the rules most of the time, but break them just often enough that your opponent cannot take for granted what you will do next and thereby set off early to meet your next shot. 

I accept that this is a rather limited tactical explanation, but it serves as a useful illustration of the cat and mouse game that opposing players must engage in. It also illustrates Picasso’s point that to become an artist you need to know the rules so that you understand how and when to break them.

That is all very well, but how does this principle translate into structural engineering? The structural engineering rule book is provided by the building regulations and by codes of practice. Once a structural arrangement has been selected, a creative process in and of itself, codes and regulations generally provide a fixed methodology for justifying its design, however for several reasons this is not always helpful. You have not mastered structural engineering until you know when and how to depart from their strictures.

In a prior post about pile cap design I demonstrated that a foundation supported by just two piles can be designed in multiple, equally valid, ways. This, however, is not the only reason to think twice about the rule book.

Many current standards have been in use for 20 years or more. It is inconceivable that nothing new has been learned in that time, which could be captured in future standards. It takes time for standards to be revised, however until they are there is no reason why an experienced practitioner cannot take advantage of newer information.

Another reason would be that codes are necessarily general documents intended to cover a broad set of circumstances, however they have evolved to their present form based on what already exists and is common. Consequently, an engineer must know the limits of application for codes of practise and must, when necessary, look to other approaches when something is uncommon.

I think most engineers, though not all, would accept that a design code may not, on some occasions, produce the most efficient design possible, but perhaps fewer would recognise that from time to time codes are habitually applied incorrectly because they are badly written or because they are old and their original meaning has been forgotten. 

Fewer still would recognise that codes can sometimes be plain wrong. While there are some well known examples, identified through catastrophic failure, there are others that are harder to spot, because the circumstances in which they are wrong is rare.

We have learned in this post that a novice tennis player who returns a shot received from down the line back up the same line is not the same as the master who returns up the line to exploit his opponent’s premature movement across the court. 

Similarly, the novice engineer who ignores the requirements of the relevant code or standard through ignorance is not the same as the experienced engineer who sets aside their provisions with good reason.

It is, as Picasso says, necessary to learn the rules so that you can break them.

Postscript

Some may question whether it is legal to ignore codes and standards. It is therefore worth noting what the Building Regulations have to say: 

Approved document A, applicable in England & Wales, says:

‘There is no obligation to adopt any particular solution contained in an approved document if you prefer to meet the relevant requirement some other way’

The technical Handbook, applicable in Scotland, echos similar sentiments when it says:

‘The regulations are mandatory, but……it is quite acceptable to use alternative methods of compliance provided they fully satisfy the regulations’