Dynamic behaviour of pre-stressed concrete transmission poles under synoptic wind loading

Abstract

A numerical model capable of predicting the dynamic response of pre-stressed concrete transmission poles under both the mean and fluctuating components of synoptic wind loads is developed in this study. A full non-linear dynamic analysis is conducted under a time history variation of wind velocity. The peak total responses, such as conductors’ reactions and poles’ base moments, are determined from this analysis. The same analysis is repeated in a quasi-static manner. Dynamic amplification factors (DAF), defined as the ratio between the maximum response based on a non-linear dynamic analysis and the corresponding value based on a quasi-static analysis, are calculated for the poles and the conductors to quantify the dynamic impact of synoptic wind loads. This factor is used to assess the importance of including the resonant component while estimating the response of the transmission poles. In addition, gust response factors (GRF) defined as the ratio between the peak and mean responses are evaluated and compared to GRF recommended by ASCE-74 (2010). A parametric study is conducted on three pre-stressed concrete transmission line systems. The mean value of the incoming wind speed is the main variable included in the parametric study. It is found that the resonant effect is dominant in the conductors at low wind speeds and the poles exhibit high dynamic response at higher wind speeds.