Fractal Characteristics And Fractal Simulation Of Typical Wind And Wind Pressure

With the progress and development of science and technology and the maturity and perfection of basic theories in the related fields of civil engineering,it is possible to build complex and soft architectural,and this kind of building structure usually produces large wind-induced response.Therefore,it is one of the necessary steps to carry out wind resistance analysis to it.The most important factor for wind resistance analysis is the wind speed or wind pressure.The numerical simulation of wind speed and wind tunnel test have become an important way to study the characteristics of wind speed or wind pressure.Fractal theory is used in the related fields of civil engineering.In wind engineering,it is mainly used to analyze the fractal characteristics of wind speed or wind pressure and the prediction of wind speed.In fact,these applications are summarized as two points,one is fractal characteristic mechanism analysis,and two is fractal simulation.In this paper,we will further study and improve the fractal simulation of wind speed and wind pressure.Wind tunnel tests on different wind fields are carried out firstly,and wind speed and wind pressure time histories of different wind fields are chosen as sample.Then it introduces the traditional method of numerical simulation of wind speed,the harmonic superposition method and the fractal simulation method of wind speed,which takes the fractal dimension as one of the parameters into the simulation of wind speed,and also introduces the fractal simulation method of wind pressure on the building surface of different wind fields.Secondly,the harmonic superposition method was used to simulate the wind speed of the three types of wind fields of A,B and C,and the box dimension,turbulence and power spectrum of the simulated wind speed in all kinds of wind fields were calculated,and then compare them with the box dimension,the turbulence and the power spectrum of the wind speed by the fractal simulation method and the wind tunnel test,finding the box dimension of the wind speed simulated by the harmonic superposition method unchanged almost in three kinds of wind fields.This method can not show the fractal characteristics of wind speed in different wind fields.Finally,the power spectrum of wind speed obtained from the three ways is analyzed from the perspective of self similarity,and the reasons for this phenomenon are explained.Then,the rescaled range analysis method is used to verify the fractal characteristics of wind speed in three types of wind fields of A,B and C in wind tunnel test,and the fractal characteristics of wind by fractal simulation method are verified by the rescaled range analysis method.The results show that the wind of fractal simulation method has obvious fractal characteristics,It shows that the fractal simulation method can effectively reflect the fractal characteristics of wind speed.This step further improves the fractal simulation method of wind speed.Finally,the fractal function WM function is taken into the wind pressure simulation of low housing surface in different wind fields,and the box dimension of wind pressure time history of various wind fields and the change law of box dimension in wind tunnel test are compared.The fractal function is also applicable in the simulation of wind pressure,and it can make the wind pressure of building surface in different wind fields have different fractal characteristics.