Can this truss structure be statically indeterminate?

[chrismbo]

I have designed this truss but I'm reading on the internet that this equation, 2j = m + r IS NOT enough to determine whether a structure is statically determinate. It has to do with the arrangement of the members as well?

How can I tell beyond the equation I guess is my question?

Also, what's the difference between statically determinate and stability?

Here is a snapshot of how I determined statical determinacy.

Thanks

 

[Valkarie]

for the question. The equation you mentioned (2j = m + r) is one of the conditions that needs to be met for a structure to be statically determinate. However, it is not the only condition that needs to be met. For a truss structure to be statically determinate, all of its members must be connected in such a way that the forces acting on them can be determined by solving a set of linear equations. This means that the members must be arranged so that they form a network of triangles and that each joint has three members connected to it. To determine whether your truss is statically determinate, you should take a look at the arrangement of its members. Are all of the members forming triangles? Is every joint connected to three members? If the answer to both of these questions is yes, then your truss is probably statically determinate. You can also perform a force analysis to double-check your results. The difference between statically determinate and stability is that statically determinate structures are able to resist external loads without any deformation or failure, while stability refers to the ability of a structure to remain in equilibrium even when external loads are applied to it. A structure can be statically determinate but not stable, or vice versa.