Evaluation of the Seismic Behaviour of Steel Transmission Towers with Different Boundary Conditions

摘要

This study shows an impact assessment of how different boundary conditions at the bottom of steel towers affect dynamic behaviour which is one of basic examinations of the improvement of seismic performance of a transmission tower which is universally-adopted in Japan. Analysis models of a single steel tower considering simplified effect of transmission lines were established. Assuming 2 cases of boundary condition, one is an ordinary 4 pointed support and the other is a 3 pointed support, the impact of ground differential settlement at the time of earthquake was examined. Then differences between and vibration characteristics and dynamic behaviour of the both models were clarified. This led to the fact that the 3-pointed support structure of steel towers caused by differential settlement greatly affects the seismic performance of steel towers at the time of earthquakes.