# Lateral compression of rectangular tube

1. Mar 24, 2015

### Colnago

Hi guys,

Bit of a noob engineer here so looking for some guidance.

I'm designing a fixture which will be constructed from stainless steel rectangular tube as shown in the diagram. If I apply a 10,000kg weight over a 100mx100mm area how do I go about calculating the stress and ultimately safe working load?

The tube will be laid flat on the ground. Is this just a case of force/area? I'm struggling to find any textbook examples of loading applied to hollow sections in this way.

2. Mar 24, 2015

### Staff: Mentor

You probably need to do some finite element stress analysis. I can't think of a way of simplifying it. Maybe someone else can.

Chet

3. Mar 25, 2015

### smithson1984

Hi Colnago,

I'm no structural engineering expert but I would start with a shear stress calculation. Check the following link under the heading 'Beam shear' for an equation:

http://en.wikipedia.org/wiki/First_moment_of_area#Statical_moment_of_area

The equation is usually used for simply supported beams, rather than one which is supported throughout it's whole length but I think it is still valid. Maybe someone else could confirm.

4. Mar 25, 2015

### paisiello2

Assuming we are talking about a local failure here and not a larger beam failure.

I see two possible local failures:
1) the horizontal face failing by bending
2) the vertical faces failing by buckling or crippling

You would have to make an assumption about the effective width of each face. You could come up with a less conservative design with FEM but probably not worth the effort practically.