AN ECCENTRICALLY STIFFENED SHELL ELEMENT MODEL WITH GEOMETRICALLY NONLINEAR CAPABILITY

A stiffened shell element is presented for geometrically non-linear an alysis of eccentrically stiffened shell structures. Modelling with thi s element is more accurate than with the traditional equivalent orthot ropic plate element or with lumping stiffeners. In addition, mesh gene ration is easier than with the conventional finite element approach wh ere the shell and beam elements are combined explicitly to represent s tiffened structures. In the present non-linear finite element procedur e, the tangent stiffness matrix is derived using the updated Lagrangia n formulation and the element strains, stresses, and internal force ve ctors are updated employing a corotational approach. The non-vectorial characteristic of large rotations is taken into account. This stiffen ed shell element formulation is ideally suited for implementation into existing linear finite element programs and its accuracy and effectiv eness have been demonstrated in several numerical examples.