Tracing the fundamental and secondary equilibrium paths of geometrically nonlinear space trusses using the modified Riks/Wempner method

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Virginia Polytechnic Institute and State University


The modified Riks/Wempner method was examined for elastic, geometrically nonlinear space trusses. A computer program, RWCNR, was developed using the Riks/Wempner algorithm. The study includes an examination of three trusses, of which two exhibit bifurcation.

A method of branching onto secondary equilibrium paths was studied, and the computer program incorporates this concept. This method of branching was found to work well provided the intersection of the fundamental and secondary equilibrium paths is good.

The computer program was found to be very useful and reliable. It successfully traced fundamental equilibrium paths, located critical points (load levels), and branched onto secondary equilibrium paths.

The modified Riks/Wempner method was found to be a very reliable method of obtaining equilibrium paths up to, and beyond, limit points, and it could branch onto secondary equilibrium paths.