A co-rotational framework for quadrilateral shell elements based on the pure deformational method

In this paper, a novel co-rotational framework for quadrilateral shell element allowing for the warping effect based on the pure deformational method is proposed for geometrically nonlinear analysis. This new co-rotational framework is essentially an element-independent algorithm which can be combined with any type of quadrilateral shell element. As the pure deformational method is adopted, the quantities of the shell element can be reduced, such that it needs less computer storage and therefore enhances the computational efficiency. In the proposed framework, the geometrical stiffness is derived with a clear physical meaning and regarded as the variations of the nodal internal forces due to the motions and deformations of shell element. Furthermore, the warping effect of quadrilateral shell element is considered, and for this reason, the structures undergoing significant warping can be efficiently solved by the proposed formulation. Finally, several benchmark examples are used to verify the validation and accuracy of the proposed method for geometrically nonlinear analysis.