A COROTATIONAL FORMULATION FOR GEOMETRICALLY NONLINEAR FINITE-ELEMENTANALYSIS OF SPATIAL BEAMS

co-rotational procedure is presented in this paper for handling arbitr arily large three-dimensional rotations associated with geometrically nonlinear analysis of spatial beam structures. This procedure has been incorporated into two commonly used 3-D beam elements, the 2-node cub ic beam element and the 3-node superparametric beam element, in our in -house general purpose finite element program, VAST. In the present pr ocedure, the element tangent stiffness matrices are generated by using the standard updated Lagrangian formulation, while a co-rotational fo rmulation is employed to update the internal force vectors during the Newton-Raphson iterations. A number of example problems have been anal yzed and the result are in good agreement with analytical or published numerical solutions.