Mixed finite element method for analysis of coupled shear/core walls

Abstract

Theoretically, the finite element method can be applied to any type of building structure. However, not all elements are suitable for coupled wall analysis. Basically, the plane stress elements that model the walls should: (1) Have in-plane rotations defined as vertical fiber rotations in order to allow direct connection and ensure compatibility with the beam elements; (2) be able to represent the strain rate of pure bending so as to avoid parasitic shears; and (3) span at most only one story so that stress discontinuities at floor levels can be allowed. In this paper, two existing elements, namely Cheung's beam-type element and Kwan's strain-based element, which satisfy these criteria, are combined together to model shear/core wall structures so as to make the best use of these two elements. Two transition elements that behave like Cheung's element at one vertical edge and like Kwan's element at the other vertical edge are developed. The two existing elements and the two newly developed elements together form a family of wall elements with same degrees of freedom. Examples are given to illustrate the versatility and accuracy of such a mixed finite element method.