We are designing one vessel as per Wind Design Code BS-6399 Part 2, 1997.

This is vertical equipment supported on lug with its bottom TL elevation as 7.2m from ground.

When we designed this equipment in PVElite using BS-6399 Part 2, 1997 in wind analysis option with input in the cell "Base Elevation" as 7.2m, we got following output.

Compute the Wind Pressure [qs]:
= 0.06251 * Ve²
= 0.06251 * 37.788²
= 89.266 kgf/m²

The Final Adjusted Wind Pressure [P]:
= Cf * q * (1 + Cr)
= 0.800 * 90.192 * (1 + 0.210 )
= 87.339 kgf/m²

We wanted to know formula for calculating the value of "q" i.e. 90.192 in "The Final Adjusted Wind Pressure [P]", as this value is not matching with term "qs" calculated in "Compute the Wind Pressure [qs]", i.e. 89.266?

We also observed that as per BS-6399 Part 2, 1997 clause no. 2.1.3.6 Overall loads, formula for calculation of "P" is given as follows:

P = 0.85( P-front – P-rear) (1 + Cr)

We wish to know why this factor 0.85 is not apearing in formula for calculation for "The Final Adjusted Wind Pressure [P]"?

Also have a note that when we changed the input for "Base Elevation" to 0.0m, we found that the values of "q" & "qs" both matched to 66.273.

We wish to know why values of "q" & "qs" both matched when we considered "Base Elevation" as 0.0m?

We have attached PVElite files with both option of Base Elevation as 7.2m & 0.0m for your ready reference.

Thanks.

Have A Nice Day!!