Equivalence of finite elements and analogous frame modules for shear/core wall analysis

Abstract

Tall shear/core wall buildings may be analysed by the finite element method or the frame method. However, actual applications of these methods are not straightforward. For the finite element method, many lower order elements are found to be subjected to parasitic shear, which greatly stiffens the elements in their response to bending. On the other hand, the conventional frame method is afflicted by parasitic moment, which causes artificial flexure of the wall elements and thereby softens their response to shear. Various techniques, e.g. reduced integration, addition of bubble function and strain function formulation etc., have been used to eliminate parasitic shear, and several alternative analogous frame modules have been developed to overcome the parasitic moment problem. In this paper, it is shown that the various four-noded rectangular finite elements with parasitic shear removed and the analogous frame modules for dealing with parasitic moment are actually all equivalent to each other, though they look very different. Hence, the two separate methods are unified. Some important points on their applications are also discussed.