Spatial and temporal statistical characteristics of air density and its influence on basic wind pressure: a case study of Shandong Province, eastern China

  Objective  The determination of basic wind pressure is particularly important for evaluating the design value of wind load of resistance structures. Air density is one of the basic parameters for calculating basic wind pressure, and its value is affected by geomorphology and climate type. Therefore, it is of great significance for wind load assessment to study the spatio-temporal statistical characteristics of air density and its influence on basic wind pressure.

  Method  In this paper, based on the air temperature, air pressure and wind speed data of 123 meteorological stations in Shandong Province of eastern China from 2005 to 2017, the probability distribution characteristics of air density and its variation with cold and warm season and spatial distribution were calculated and analyzed. Combined with the design wind speed obtained from the statistical analysis of Gumbel distribution, the influence of air density on the basic wind pressure was discussed.

  Result  (1) The probability density function of air density in the whole season was bimodal. After distinguishing the cold and warm seasons, the fitting accuracy of the probability density function was improved with the probability density functions of Gamma, Weibull, Burr and GEV. The air density distribution functions of cold and warm seasons fit well with Weibull and Burr functions, respectively. (2) The air density decreasesd from the coast to the inland, and decreased with the increase of altitude. (3) In the low altitude plain areas, the wind pressure calculated by the average air density in the cold season was almost the same as that calculated by the fixed air density 1.25 kg/m³ and considering the effect of altitude on the air density, while in the high altitude area, the wind pressure calculated by the fixed air density of 1.25 kg/m³ was on the high side. (4) For the low altitude plain area of Shandong Province, the basic wind pressure calculated by selecting the extreme air density was about 10%−14% higher than that calculated by the fixed air density of 1.25 kg/m³ and considering the effect of altitude on the air density.

  Conclusion  In this study, through the statistics of space-time characteristics of air density and combined with the extreme wind speed, the influence of different air density on the basic wind pressure was discussed, which provides an important reference for the selection of air density in structural design.