Design Capacity of T-Strut Subject to Compressive Force
T-struts subject to centroid compression buckle flexural-torsionally about their axis of symmetry. When the force is applied at the shear center of the section, T-struts buckle either flexurally or torsionally without coupling of flexure with twisting. Although the buckling load of shear center loading is greater than that of centroid loading, i.e. T-struts in elastic stage provide larger resistance to buckling about their axis of symmetry when the compression is applied at the shear center in lieu of the centroid of the section, T-struts with defect such as fabrication error, load eccentricity and residual stress always buckles in the elastic-plastic range actually, and the design capacity decrease by shifting the working line of a T-section compression chord to the shear center. That peculiarity is verified by the nonlinear buckling analysis of T-struts models in ANSYS.
X. L. Xiong et al., "Design Capacity of T-Strut Subject to Compressive Force", Advanced Materials Research, Vols. 163-167, pp. 550-556, 2011