On-Site Measured Gust Response Factors of Transmission Towers Based on SHM System

Abstract

Many transmission towers have collapsed during typhoon events, and the design wind loads in most current standards consider only the turbulence characteristics of monsoons. The gust response factor (GRF) is a parameter that is directly related to the wind field characteristics, and thus, it is necessary to address GRFs under typhoons to improve the calculation methods of design wind loads. First, the calculation methods of the GRF for transmission towers in various standards are introduced and compared. Then, two operational transmission towers are selected to carry out full-scale measurements, followed by detailed descriptions of a structural health monitoring (SHM) system. Finally, the GRFs are calculated based on on-site measurements during monsoon and three observed typhoon events. The measured results show that a higher turbulence intensity leads to a greater GRF. At low wind speeds, the larger the wind speed, the smaller the GRF; inversely, at high wind speeds, a larger wind speed leads to a greater GRF with a critical wind speed of approximately 9 m/s. Most of the measured GRFs are larger than the standard values, indicating that the current standards underestimate the GRFs of transmission towers. In typhoon-prone areas, the GRF of a transmission tower is recommended to be at least 3.0 to ensure structural safety.