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I want to mount two patio heaters on my terrace in front of a window wall. I cannot attach anything directly to the window wall so I am going to run an aluminium box beam between two brick columns. The beam will be 5000mm long. The beam dimensions are 80mm x 40mm with a 4mm thick wall, 13kg in weight. The heaters weigh 6.5kg each and are 1000mm long. They will be 1000mm from each end and therefore 1000 from each other. I need to drill 8 x 8mm holes for mounting brackets (2 brackets per heater, 2 holes per bracket).

I am sure the beam will deflect a little - any serious risk of collapse? Patio Heater Attachment Points Proposed Positioning

James Cotton
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1 Answers1

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Load equations

Using the 5th equation from the bottom the displacement is:

disp = Wa^3b^3/3EIL^3

We can superimpose it for each of your loads. Essentially your beam is loaded with 3.25kg (~33N) at 4 points (1,2,3,4m along).

I.e. disp(total) = disp(1st load) + disp(2nd load) ... + disp(4rth load)

For all the loads W = 33N

for the first and fourth a = 1 and b = 4 for the second and third a = 2 and b = 3

E = 69 x 10^9 (Elastic Modulus of Aluminium)

I = 7.11x10^-7 (Second moment of Area)

Ends up being:

disp = 0.001m

So at the middle x = 2.5

So displacement = 0.0025m

Sounds like it should be fine.

m4p85r
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