Reciprocal force diagram

A simple definition showing the generation of a reciprocal force diagram for a compression only structure. When the forces are in equilibrium (ie the dynamic relaxation part has stopped moving), the vectors in this reciprocal diagram form closed polygons.

Note that here the reciprocal diagram is being generated from the equilibrium model, rather than the other way around, so it is not an essential part of the process as it is with the thrust network analysis approach, but still, I think this alternative way of viewing the forces can be quite revealing.

Also note, that here the masses are being kept constant, rather than updated during the form-finding to reflect the changing areas, but more on that to follow soon.

Attachments:

ReciprocalForce.gh, 67 KB

Replies to This Discussion

Permalink Reply by Dragos Naicu on April 24, 2014 at 10:02am

I think this is great. It is, as you say, revealing. I was recently asked by a lecturer if I think graphic statics should be taught at uni, and I said yes exactly for that reason. Because seeing that there is this alternative way to look at structures (static analysis) would expand the ideas of young engineers, even if they do not end up using it.

Permalink Reply by archz2 on September 28, 2019 at 7:03am