[Objective]Characteristics of spatial correlation of near-ground typhoon constitute important parameters to calculate wind-induced dynamic response of engineering structures,such as long-span roofs and bridges.Based on wind field measurements with matrix-layout anemometers during the landfall of typhoon"Sudiro",the spatial correlation of typhoon wind fields near coastal areas is investigated.[Methods]Based on the measured wind speed and direction data of typhoon"Sudiro"using array anemometers,288 wind-speed samples from four stable periods were selected to conduct a detailed analysis of the spatial correlation of the typhoon's near-ground wind field.First,the influence of average wind speed and wind direction angle on the vertical and horizontal cross-correlation coefficients of fluctuating wind speed in the clockwise,cross wind,and vertical directions was qualitatively studied.Then,the influence of average wind speed and wind direction angle on vertical and horizontal coherence functions of three types of fluctuating wind speeds was analyzed.Finally,formulae were fitted for the vertical coherence function in the clockwise direction,the horizontal coherence function in the clockwise direction,and the horizontal coherence function in the crosswind direction,and values of relevant parameters were given.[Results]The average wind speed exerts a certain influence on vertical and horizontal cross-correlation coefficients and coherence functions in clockwise and crosswind directions.The higher the average wind speed reaches,the greater the corresponding cross-correlation coefficients and coherence functions become.The wind direction angle exerts little effect on the vertical correlation of three types of fluctuating wind speeds,but executes a greater impact on the horizontal cross-correlation coefficient and coherence function in clockwise and crosswind directions.Values of various coherence functions at zero frequency(f=0 Hz)are mostly less than 1.0,and those at the zero frequency exhibit an exponential decay with the ratio of distance to average wind speed.Attenuation coefficients of the downwind vertical coherence function,downwind horizontal coherence function,and crosswind horizontal coherence function with distance to average wind speed ratio equal 9.3f+0.38,3.1f+0.18,and 3.2f+0.16,respectively.[Conclusions]In this article,we analyze spatial-correlation characteristics of the typhoon wind field as well as vertical and horizontal cross-correlation coefficients and coherence functions.Proposed fitting formulae can be used for the dynamic response analysis and calculation of large-span spatial structures and bridge structures,and can effectively evaluate the wind resistance safety of engineering structures.
typhoon measurementmatrix layoutanemometercross-correlationcoherence function
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