Revisit of underestimated wind drag coefficients and gust response factors of lattice transmission towers based on aeroelastic wind tunnel testing and multi-sensor data fusion

Abstract

Accurate estimation of extreme wind-induced loads is key to the cost-effective and reliable performance-based design of overhead lattice transmission towers. Particularly, drag coefficient and gust response factors are among the main aerodynamic properties of these structures for the estimation of equivalent static wind loads. Wind design standards recommend values for these key properties for generic lattice frames based on the solidity ratio and height of the frames. However, the geometric properties of lattice transmission towers often vary along the height of the structure. Therefore, local drag coefficients and gust response factors of transmission towers must be assessed to reliably analyze the extreme wind performance of towers. This study estimates the drag coefficients and gust response factors of a double-circuit lattice transmission tower using an approach based on Kalman filtering. Multiple along-wind and crosswind responses of the tower were obtained from a series of aeroelastic wind tunnel tests that were conducted at the National Science Foundation (NSF) Natural Hazard Engineering Research Infrastructure (NHERI) Wall of Wind Experimental Facility (WOW EF) at Florida International University (FIU). The developed Kalman filtering model facilitates the fusion of noisy measurements from multiple sensors of the same and different types that were implemented in the wind tunnel experiments. This approach is integrated with an optimization technique to provide estimates of wind load parameters of interest with high spatial resolution and accuracy from measured responses. The derived drag coefficients and gust response factors are treated as new evidence along with the ASCE manual recommendations for these properties as priors in a Bayesian regression model to provide new recommendations. The findings of this study indicate larger drag coefficients and gust response factors than those suggested by ASCE No. 7 and No. 74 by up to 12% and 13%, respectively.