Stability Bearing Capacity Evaluation for Cross-Bracings Considering Spatial Torsional Effect in Transmission Towers

As main load-bearing members, the stability of cross-bracings could directly affect the safety of the whole transmission towers. In the accidental case of a ruptured cable on one side, transmission towers will be subjected to torsion loads. In this paper, the stability bearing capacity of cross-bracings considering spatial torsional effect is evaluated. First, the experimental study on a full-scale double-panel spatial subassemblage of transmission towers under a torsion load is investigated. Then, the establishment and validation of its finite element (FE) model are carried out, and the parametric analysis of the stability bearing capacity of cross-bracings considering spatial torsional effect is conducted. Finally, a modified mechanical mode of cross-bracings considering spatial torsional effect is proposed by the theoretical analysis. The results show that the failure mode of cross-bracings is the minor-principal axis flexural buckling, and the spatial torsional effect would reduce the stability bearing capacity of cross-bracings by 10.2%, but not change the buckling mode. Moreover, the increase of all geometrical and material parameters can enhance the stability bearing capacity of cross-bracings. Additionally, the predicted results of proposed modified mechanical model are in good agreement with the experimental and FE results.