Analytical method for the lateral buckling of the struts in beam string structures

In the beam string structure (BSS), the moment in the beam is effectively reduced by means of the strings and the struts. As a result, the beam is very slender and the BSS is suitable to cross a long span. In the BSS, the struts can be considered as supports for the beam through the strings. Usually, the struts are in compression, they should be designed to avoid buckling, but few researches can be found about the lateral buckling of the struts in the BSS. Because one end of the struts is jointed to the beam while the other end is connected to the strings, the buckling of the struts not only depends on the length of the struts and the rotational stiffness of the joints, but also depends on the rise and the lateral stiffness of the beam, the layout of the strings and the number of the struts. In this paper, the lateral buckling of the struts in the BSS is investigated according to the following items: (1) analytical method to formulate the lateral buckling load of the strut for one-strut BSS and multi-strut BSS; (2) parameter studies of the lateral buckling load of the strut for one-strut BSS; (3) numerical analysis of a 3-strut BSS by means of the suggested analytical method and the geometrically nonlinear finite element method.