Stability of Baker Trusses

L.W. Bleker

Delft University of Technology, the Netherlands
Skidmore, Owings & Merrill, Chicago, USA

Baker Trusses have the ability to be more efficient in material usage than conventional truss types and are thus of interest to be considered by engineers. It is known that under certain parameters and load conditions the web-nodes of a Baker Truss can become unstable in the out-of-plane direction. Up to now the way in which for this failure mechanism is checked in practice, is by calculating the member forces and the geometric stiffness of each web-node. In this paper, two equations are given; one for a top-loaded and one for a bottom-loaded Baker Truss, allowing for direct calculation of the web-nodal geometric stiffness without the need to calculate the member forces. These equations show that most web-nodes for the top-loaded condition are unstable and that most web-nodes for the bottom-loaded condition are stable.

Key words: Baker Truss, geometric stiffness, stability