Study On Static Stability And Windinduced Response Of Steel Cooling Tower Considering Stressed-skin Effect

Cooling towers play a very important role in thermal power generation.With the advancement of society and the development of industry,the size of cooling towers has become larger and larger,and the structural forms have become more and more complex.The defects of concrete materials have become increasingly prominent.Steel structure cooling towers have the advantages of light weight,convenient construction,high cooling efficiency and flexible structural system layout,and are gradually replacing traditional materials.The cooling tower is a high-rise structure,and wind load has a great impact on the structural performance.The steel structure cooling tower surface is covered with panels,which will produce a skin effect when stressed,which has a certain impact on the overall mechanical performance and stability of the structure.For the research of steel structure cooling towers,the skin effect has not been considered.Therefore,this topic mainly considers the effect of steel structure cooling tower skin effect on the overall structural stability,and establishes a finite element modeling and analysis method of structure considering skin panels.Considering the static stability analysis of the skin structure cooling tower,and based on the overall structure wind tunnel test,the wind vibration response and wind coefficient analysis of the structure are performed.The main work is as follows:1.Consider the different connection methods of the skin panel and the member,The finite element analysis model of cooling tower structure considering skin effect was established in ANSYS.Based on the principle of three-way stiffness equivalent,the modeled aluminum plate was equivalent to an anisotropic flat plate,and the finite element verification was performed.By comparing the calculation results of different models,it is finally determined to use spring elements to simulate the self-tapping screw connection between the connection panel and the rod.In order to obtain the self-tapping screw stiffness curve,a series of self-tapping screw shear performance tests were designed and carried out.The load-displacement curves under different connection plate thicknesses and screw diameters were obtained.The simplified structure was used as the spring stiffness curve to enter the overall structure calculation model.2.Carry out pressure tunnel wind tunnel test of rigid model of steel structure cooling tower,simulate the Reynolds number effect by increasing the outer surface roughness,and simulate the internal members of the structure by sticking strips on the internal surface to obtain the inside and outside of the structure,respectively.The wind pressure coefficient distribution on the surface is compared with the specifications.Then,the wind pressure points obtained from the wind tunnel test are interpolated and encrypted.Based on the time history analysis method in the finite element software ANSYS,the wind vibration response analysis is performed on the structure to obtain the displacement response time history of each position of the structure,and the displacement wind vibration coefficient is calculated.It is found that the displacement wind vibration coefficient is smaller on the windward side and larger on the leeward side,and it decreases first and then increases along the height.3.The nonlinear stability analysis of the steel structure cooling tower considering the skin panel is performed.The parameters of height,grid size,panel thickness and spring stiffness are considered to analyze the nonlinear stability parameters of the steel structure cooling tower.The influence of parameters on the stability performance of the structure,and a detailed analysis of typical examples,extracting the stress state of the spring,summing the distribution of node stiffness and the failure modes of different grid structures,and obtaining different failure modes and grid sizes Depending on the size,when the grid size is small,in addition to the throat depression,local instability also occurs in the wind suction area,which eventually leads to overall instability.