Characteristics of wind induced net force and torque on a rectangular sign measured in the field

• Mean and torsion coefficients for a sign are developed using 470 full scale data records.
• Mean force and mean torsion coefficients are at their maximums at different angles of attack.
• Correlation of force and torsion coefficients varies as a function of angle of attack of wind.
• Mean extreme estimates closely match the observed peak values.
• Mean and pseudo steady force coefficients are approximately equal for critical angles of attack.

Full-scale field tests for a billboard sign are conducted at the Wind Science and Engineering (WISE) field site to provide a benchmark for model scale tests performed in the wind tunnel. The field site is located at the Reese Technology Center in Lubbock, Texas. The aspect and clearance ratios for the sign are 2.0 and 0.5, respectively. Wind induced forces and torques on the full scale sign are established using 470 15-min duration records. All the records used are stationary in speed and direction and have mean wind speeds greater than or equal to 15 mph (6.7 m/s). The characteristics of the parent and joint distributions for force and torque acting on the sign are presented herein. The characterization includes empirical functions to describe the mean, standard deviation, skewness, kurtosis, and their correlation in time as a function of angle of attack. Mean extreme force and torsion coefficients are provided along with mode and dispersion parameters for the Fisher–Tippet Type I distribution. Two estimation techniques to compute the mean extreme value are investigated. The performance of each technique is evaluated by comparison of the mean extreme value to measured peak values. Model scale mean force coefficients obtained in the wind tunnel and available in the literature tend to overestimate those from the full scale tests.