Searching for a Structural Engineer who specialises in ...

[ToughButterCup]

... louvres.  I have this little problem  

 

In brief: how do I support our louvres?

 

The end in mind is to remain comfortably tucked up in my little wooden bed, sound asleep when the inevitable hooley  breaks.

I can probably cobble something together myself just by looking at how local hit and miss boarding is supported in local barns. But our louvres are set 'on edge' , rather than face on like hit and miss boarding.

 

Yes, @Russell griffiths, I'm probably over-thinking this, but I tell ya wot, I love my sleep - I need to be at least reasonably confident that they won't pop their moorings and smash down-wind windows.

 

So, anyone know of an SE who has worked in this area? Or know someone who might be able to refer us to an appropriately experienced SE?

[Russell griffiths]

What ya mention me for. 

Get a bunch of big nails and you can sleep easy. 

[Jeremy Harris]

Not hard to do some quick calcs to show how strong any fastenings need to be.  The force from wind on a louvre that was in free air (worst case, as in your situation the louvres are going to partially shelter each other) is given by the projected area of the louvre (i.e. the face perpendicular to the wind) and the wind velocity.  The equation is the standard drag equation:

 

F = 0.5·ρ·C_D·A·V²

 

Where:

 

F = force (in Newtons)

ρ  = air density in kg/m³ ( normally about 1.225 kq/m³)

C_D = drag coefficient, assume this is 1 to make the sums simpler

A = projected area (largest face of the louvre) in m²

V = maximum anticipated wind speed, in m/s

 

So, for a 100mm wide louvre, 4m long, facing a wind speed of 100mph (~45/m/s), the force imposed by the wind would be 0.5·1.225·(0.1·4)·45² = ~496 N, or around 50.6 kgf. 

 

Taking an extreme case, where the louvre was fastened with a single 6mm diameter bolt in tension at top and bottom, and ignoring the possibility of bolt break out through the timber, then each bolt has a maximum tensile strength of about 10 kN, so two M6 316 stainless bolts in tension could withstand around 20 kN, or around 40 times the force exerted by a 100mph wind on a  4 metre long louvre.

 

So, the short answer is that pretty much any fastening is going to be an absolutely massive overkill in terms of ultimate strength versus wind loading on these louvres, so don't worry an SE with it, just bolt the things in place.  The more significant issue is really stiffness - if fixed so they don't flex much they will be absolutely rock solid in terms of fixing strength to resist wind loading.

[ToughButterCup]

Thank you very much indeed @JSHarris. That was very kind.

Like the other man said 

31 minutes ago, Russell griffiths said:

[...]Get a bunch of big nails and you can sleep easy. 

 

was as close to bang on correct as you can get. (Typical ? )

 

9 minutes ago, JSHarris said:

[...]

The more significant issue is really stiffness - if fixed so they don't flex much they will be absolutely rock solid in terms of fixing strength to resist wind loading.

 

For stiffness, I think  that simply copying local practice will more than likely suffice: rip cut a piece of 4 by 4 along its diagonal and fasten. If I double this up on the longer 4 meter sections, and stagger the support timber so that each one partly straddles a neighbouring set of verticals  then I will be able to sleep peacefully.

 

[Russell griffiths]

have you thought about an aluminium transom bar, those used for roofing, router out a groove in your timber and insert bar, stainless nuts and bolts, could look a bit special, have you thought about a different finish to the timber on that facade, might make it stand out nicely. 

[Russell griffiths]

Here you go chummy.