Too much wind!

I hate the wind code with a passion that is normally reserved for exciting sport, a fine wine or a good woman. Actually, at the risk of being accused of sexism, you could mix all those adjectives up. Fine sport. Good wine. You get the point.

Allow me to explain.

I am obliged to design buildings for the loads to which they can expect to be subjected during their life, including the wind blowing on it. These loads are generally defined by British Standards and BS6399-2:1997 “Loading for buildings. Code of practice for wind loads” is a bloated behemoth of document that has as much connection with the real world as the Chuckle Brothers.

The principle is simple enough. You check the wind loads for a north-south wind, then again for an east-west wind. If the wind blows from any other direction, it is simply a combination of the two so no further check would be required. Or at least, you would think so. The code, rightly, factors in stuff like whether the building is lightweight or heavy, in a town or in the country, or in a valley or on top of a hill. All perfectly laudable and perfectly sensible. Until you open the British Standard that deals with such things.

Within moments you are buried beneath a whole rack of tables, factors and coefficients that are discombobulating at the best of times, but in this document they are in no particular order. It’s as if someone at the BSI got hold of the galley proof and chucked the papers up in the air, collected them off the ground in a random order and sent it to the printers.

Don’t get me wrong. Wind loads can be a real problem and cause damage to buildings resulting in a deterioration of the condition or something worse. And, when it comes to Canary Wharf or the Shard, you need to consider the wind from everyone of the 360 degrees available (Section 3 of BS6399-2 – the Directional Method. Sounds like birth control). But, when one is dealing with the sort of buildings that most of us (people, not necessarily engineers) encounter, all those pages of analysis and checking result in a 5% variation in a load that accounts for a small proportion of the total load on the building. What’s the point?

Does it have to be quite so complicated? Surely there is scope for a small document that says lightweight structures in the centre of town should be designed for Wind Load A, and in the country for Wind Load B. Then, if your average humble engineer has some concerns or is trying to get a particular beam to work , he (or she) can have a delve into the more robust and complicated methods available in the Standard and check in more detail.

Why is it so complicated?