Wind Direction Reduction Factor for Design Wind Speed of High-rise Buildings Under Twisted Wind Field

Abstract:

In this paper， the calculation method of modified wind direction reduction factor of strong wind speed considering the influence of twisted flow in the design wind load estimation of super high-rise buildings is proposed. Wind tunnel tests of a square section high-rise building model under twisted and non-twisted wind fields are conducted. Using the proposed correction method， the wind direction reduction factors of design wind speeds of the Beijing and Nanjing regions are calculated. And the influence of twisted flow on the wind direction reduction effect of the aerodynamic force of the building is analyzed. The results show that there is a shift of wind pressures on the building under the twisted wind field， and the wind direction angles of the most unfavorable wind pressure under the twisted wind field are different from the cases under the non-twisted wind field. In the wind load estimation of the wind direction reduction effect， ignoring the influence of twisted flow may lead to a serious underestimate of the wind load of super high-rise buildings， making the structural design more dangerous. Moreover， the proposed correction method in this paper can effectively solve this problem.

Key words:wind load of super high-rise building;wind direction reduction;Ekman spiral;twisted flow;wind tunnel test