A CONSISTENT MASS MATRIX FOR 3-DIMENSIONAL BEAM-COLUMNS

This paper presents the development of a consistent mass matrix for a three-dimensional beam-column element via the concept of stability functions. The consistent mass matrix is developed via the assumed-modes method with shape functions being derived from the Euler equations of axial flexural interaction. The consistent mass matrix is compared with other mass matrices (lumped and consistent formulations) which disregard the effect of axial-flexural interaction. The consistent mass matrix with axial-flexural interaction has proved reliable, but its use is questionable for typical structures, in that the level of axial-flexural interaction only minimally alters the inertial forces. Curiously, as the level of axial-flexural interactions increases, the total amount of element rotary inertia also increases.