Failure mechanism of a Q690 steel tubular transmission Tower: Full-Scale experiment and numerical simulation

Abstract

The failure mechanism of a Q690 steel tubular transmission tower is investigated through full-scale experiment. The tower is mainly subject to the influence of the wind and the loads from the transmission lines. The displacements and the strains of the key positions as well as the ultimate bearing capacity of the tower are thus obtained. The final collapse is induced by the buckling instability of the compressed main member of a tower leg. A finite element model is established, whose validity is verified by the experimental data. Then, the numerical model is used for further analysis on the structural responses of the tower. It is found that once plasticity occurs at a certain point on the main member, its lateral displacement would be much accelerated, thus amplifying the second-order effect thereof. The horizontal auxiliary members, connected to the bottom of the compressed main member, are initially under tension. While the deformation of the main member is aggravated, they gradually undergo the transition from tension to compression, constituting a lateral support to the main member. This support then enforces the plasticity to develop towards the middle section of the main member, resulting in the final failure at the same location as observed in the full-scale experiment. These findings are crucial for a progressive understanding of the failure mechanism of this type of high-strength steel tubular towers, and they have contributed to the optimization of the design method to prevent the collapse of transmission tower under similar circumstances.