Aluminium Framework Bed Design: Load Support Tips

[cabellos]

aluminium framework...

I am designing an aluminium frame bed. I have desided to use aluminium extrusion either square or rectangular shape to form the main 4 bars at the base supported by 4 legs. I will use panels of plywood at the centre holding the mattress.

My question is...suppose the structure needs to support 90kg, should i assume an evenly distributed load of 90kg on each memeber or does it require more thought as to where most of the load is applied to the structure? - (e.g. at the top and bottom ends near the feet and head it would be at its minimum but the main 2 or 3 cross plywood panels in the centre would need to support the bulk of the 90kg)

Tips and ideas would be much appreciated...

 

[Panda]

The matress should distribute the load evenly whilst lying down providing it is thick enough to support you. Also your actual design will probably be much stronger than the requirements unless you are building it to minimise weight.
Something to take into account is instantaneous side loadings from when you sit on the edge of the bed, or when moving the bed frame, this requires the joints to be beefed up to take side loads, this will help with the static top loading.
Have you considered L section bar for the main rails, this will form a natural locating system for the bed base, also using slats rather than board allows the matress to slightly extrude through (Unless it is pocket sprung) giving a lighter bed and slight improvement on comfort.

 

[FredGarvin]

I would suggest you follow a typical design method which is to design to the worst case scenario. Once you have that, you start to make optimizing decisions. In your case, like Panda mentioned, the simple support of a distributed 90kg is probably the easiest load this thing will see. What about a 90 kg person "flopping" onto the mattress? What about someone sitting over just one leg? You need to decide if these scenarios are worth pursuing.