Wind loading on vertical panels with different permeabilities

Aerodynamic Testing of Variable Message Signs

“…In general, Quinn's et al (2001) results are consistently lower than Letchford's (2001). Giannoulis et al (2012) attributes this to a difference in the terrain category and the thickness of the model used in each study. The authors point out that Quinn's et al (2001) field measurements at Silsoe corresponded to a rural terrain category and Letchford's (2001) wind tunnel simulation was between rural and suburban terrain categories (higher roughness length).…”

“…The two primary studies by Letchford (2001) and Quinn et al (2001) are compared and discussed in detail by Giannoulis et al (2012). Specific results for these studies were discussed previously and only a comparison of the results is discussed here.…”

“…Quinn et al (2001) attributed the difference to an increase in aerodynamic area due to the addition of the frame. Quinn et al (2001) did not provide the thickness of the frame so a comprehensive evaluation was not made by Giannoulis et al (2012). However, they concluded that this was probably the dominant reason for the discrepancy.…”

“…However, they concluded that this was probably the dominant reason for the discrepancy. Force coefficients for different aspect and clearance ratios as reported by Quinn et al (2001) and Letchford (2001) was provided by Giannoulis et al (2012) and reproduced here in Table 2.3. Table 2.3 also includes the code values from the EN 1991-1-4 and ASCE 7-10 code.…”

“…Table 2.3 also includes the code values from the EN 1991-1-4 and ASCE 7-10 code. Giannoulis et al (2012) points out that Letchford's (2001) results form the basis of the ASCE 7-10 code but the published code values multiply Letchford's (2001) reported results by a factor of 1.18 to make them compatible with the way the gust factor is incorporated into the design process. The published ASCE 7-10 values are shown in parentheses.…”