A simplified analytical method for lateral dynamic responses of a transmission tower due to rockfall impact

Abstract

Transmission tower structures support high-voltage power lines that carry electricity over long distance and rockfall is one of critical disasters during its safe operation. This paper presented a simplified analytical methodology for lateral dynamic responses of a transmission tower structure due to rockfall impact. At first, the lateral dynamic displacement of a lattice transmission tower structure can be represented by a second-order partial differential equation and half sine wave was used for rockfall impact. Then, the solution can be approximated by a set of specified shape functions multiplied by time-dependent generalized coordinates. And the partial differential equation is discretized into a set of single degree of freedom system. And then the shape function can be determined by solved an eigenvalue function and the fundamental frequency of a transmission tower can was derived based on the energy method and combination synthesis method. Finally, the lateral dynamic displacements can be approximately obtained. A numerical study of a transmission tower was conducted. Parametric study of the effect of impact location height, impact duration, peak impact force, as well as the distribution of cross-arms on dynamic responses were also carried out. And the results show that the discrepancy between the analytical and the computed of fundamental frequency is less than 3%, the error of dynamic displacement is within 10%, and the fundamental frequency of the structure decreases with the increase of the tower top additional mass ratio.

Numerical Simulation of Impact Effect on Stability of Transmission Tower Foundation

“…However, due to the diverse and complex specifications of agricultural equipment and agricultural vehicles and the difficulty of modeling, simplified impactors are adopted to simulate actual agricultural equipment and agricultural vehicles; three different shapes of impactors are used to simulate the different impact surfaces of agricultural equipment and agricultural vehicles. The authors of [24] conducted numerical simulation studies on the direct impact of impactors on a transmission tower structure. The focus of this study is to analyze the deformation and stability of a transmission tower foundation under the impact effect, which means the impactor does not directly impact the transmission tower structure; that is, the influence of the impact effect on the upper transmission tower structure cannot be considered, so the transmission tower structure is not considered in the calculation and analysis process.…”