Seismic performance analysis of DC transmission tower-line system of unequal height

To explore the influence of unequal leg length combinations on the seismic performance of DC transmission towers, transmission tower models with different leg heights were established for seismic response analysis, Based on incremental dynamic analysis (IDA) method and the failure determination criteria, the dynamic stability performance of unequal tower-wire system under seismic action for $0,3,6$, and 9 m height difference was analyzed. Results indicate that the design of long and short legs makes the vibration mode of transmission tower change, and the joint of short leg and tower body with main material stress increase. The vibration phenomenon of shifting the equilibrium position occurs in the near unstable state, the impact of the unbalanced tension in the conductor of the key components damage aggravated leading to instability damage. Finally, As the height gap increases, the modal effect manifests the stress increase is particularly clear, the unequal tower leg design in the direction of the conductor should be avoided as much as possible in the construction of the project.