You can compute deflection with beam tables, but this is generally only if your particular scenario is in the table. You need two properties of the beam and material itself, the modulus of elasticity (E), and the moment of inertia about the axis of bending (I). I can be computed based on the dimensions if not tabulated somewhere, and E is based on the material. A list of deflections equations (Delta x max) is at the available link.http://www.awc.org/pdf/DA6-BeamFormulas.pdf
However, it may be difficult to find your particular configuration, you need to decide if the ends are fixed or pinned, the number of spans, loading conditions etc.
May not produce desired results.
Other alternative methods are double integration, work energy methods, and software. The beam tables are the easiest if you have the correct scenario.
However- if you have a 3-dimensional structure things may be completely different depending on how it is all bolted, welded or connected.
That's probably the only somewhat helpful information I can really provide as I don't really have a structural engineer mindset.
Maybe someone with construction experience with the particular materials and end goal can provide better help.