Field Measurements for wind profiles near ground during typhoon ‘Muifa’

Abstract:

In this paper, wind profiles of typhoon ‘Muifa’ are analyzed based on the long time measured data recorded respectively at 10,20,30 and 40 meters height levels above the ground in Pudong area Shanghai. The height of neutral ABL increases with wind speed. The average height of neutral ABL during typhoon ‘Muifa’ is 2063m by calculation, which greatly exceeds the gradient height(350m) recommended by Chinese National Load Code(GB50009-2001,2002) for open terrain. The stability parameter z/L is almost in [-0.1, 0.1] when the wind speed becomes high, which means near-neutral flow. Measured mean wind speed profile agrees well with the power law, the log law and Deaves-Harris ABL model. Based on expression form in ASCE7-10, the fitting equations of turbulence intensity profiles in longitudinal, lateral and vertical directions are presented. Finally, the formulas for gust factors are also derived using curve-fitting technique, which can provide reference for engineering designing.