On the definition of beam - wall joint rotations in the analysis of coupled wall - frame structures

Abstract

In the analysis of coupled wall-frame structures, several different definitions for the beam - wall joint rotations have been adopted. However, the various definitions used are not equivalent. By formulating the coupling beam element as a Timoshenko beam element with both horizontal and vertical fibre rotations at each end, it is shown that the proper definition for the nodal rotation at a beam - wall joint should be the rotation of the vertical fibre at the beam - wall interface; the use of other definitions may lead to errors in the effective stiffness of the coupling beams. A quantitative assessment of the errors so caused is made and it is found that in cases where the coupling beams are short and stiff, the errors could be quite significant. It is therefore proposed that existing methods which use definitions other than the vertical fibre rotations at the joints should be reviewed and, if necessary, reformulated to have the definition of the beam - wall joint rotations amended. © 1993.