Seismic responses of transmission tower-line system under multi-component ground motions

Abstract

In this study, shaking table tests, theoretical research, and finite element modeling analysis were conducted on seismic responses of a transmission tower-line system under multi-component ground motions. The rocking component of ground motion was determined from the original seismic record by the wavelet analysis. The shaking table tests for scale models (single tower and tower-line system) that satisfy the similarity ratio of an actual tower-line system, were performed under multiple directions of motion. Dynamic equations under multi-component (horizontal, coupled horizontal, and tilting (CHT), and coupled vertical, horizontal, and tilting (CVHT)) ground motions were first derived in theoretical studies. The finite element model based on the actual transmission tower line system was built, and the response of the system under the identical working condition was calculated. It is found that the rotational component of the ground motion cannot be overlooked and significantly impacts the seismic response of the tower-line system, which is reflected especially as the vertical motion is coupled. The tilting ground motion, the additional second-order effect, and the foundation tilting jointly cause the increase in the response amplitude and significant asymmetric displacement effect. Since this effect of tilting ground motions, the weakening effect of the transmission line to reduce the responses for the displacement and acceleration of the tower-line system is also weakened. It is, therefore, essential to consider the adverse effects of multi-component ground motions on the designing of transmission tower systems in high-intensity areas.