DESIGN OF IMPERFECT CROSS-BRACINGS

In recent years, several analytical studies have been conducted on the behavior of cross-bracing members subjected to out-of-plane buckling. Most of these studies do not consider boundary conditions such as the relative stiffness of the end connections and adjoining members and e ccentricity in loading. In this paper closed-form relationships are ob tained for the direct evaluation of the critical loads of cross-bracin gs with semirigid ends for any value of relative stiffness of the end connections and any ratio of the dimensionless parameters of tension a nd compression members. The criteria are formulated for the general ca se, i.e., tension and compression braces have different section proper ties, lengths, and axial loading. Parametric solutions are graphically displayed to clarify distinct behavior including the boundary separat ing symmetrical and antisymmetrical modes of buckling. Analytical expr essions for eccentrically loaded cross bracings with simple end connec tions are further derived and studied to yield a result that the tensi le force does not contribute substantially to the load-carrying capaci ty of the bracing system.