Research On Wind Induced Dynamic Responses And Fatigue Characteristic Of Windbreak Structure

The windbreak is a new structure developed for environmental protection. Its application in our country has just begun, and there is few research on its wind-induced dynamic responses and fatigue. Although the windbreaks we have built in our country were few and small-scale, with the expansion of port functions and the strengthening of environmental awareness, the large-scale and high-performance ones will be more widely applied. Thus structural design security of windbreak is an important subject we are facing, especially the structural optimization, wind-induced behavior, response and fatigue are the key issues need to be solved urgently.This work is based on one practical project, including the design method of the project and analysis of the wind-induced responses and fatigue of the windbreak.The main work includes the following aspects:1, Research on the design method of the windbreak. The main content, methods and steps of design were introduced. The design mainly includes the layout of the windbreak, the steel structure design and the infrastructure design. And the structural design for a practical project was performed.2, The simulation of the wind pressure. A fluctuating wind load of 200 seconds was generated by the Davenport spectrum according to the loading code for design of building structures.3, The static FEM analysis of the windbreak. The wind pressure, supposed as invariable force, was calculated according to the loading code for design of building structures, and the displacements and stresses of the windbreak were calculated by the static finite element method.4, The dynamic behaviors analysis of the windbreak. The frequency and vibration modes of the windbreak were calculated by the finite element method. The result shows that the first frequency of the windbreak structure is 0.460. Then the dynamic responses under different frequencies were analyzed.5, The dynamic response analysis of the windbreak. The displacement and stress of the windbreak were calculated by the dynamic finite element method with the fluctuating wind load generated by the Davenport spectrum as input. The result shows that the stress and displacement of the windbreak structure are much larger under the dynamical force.6, The wind-induced fatigue analysis of the windbreak. The most dangerous place of the structural stress was identified by the results of the transient dynamic analysis . According to the basic theory of fatigue, stress spectrum was converted into stress peak spectrum. We got the stress amplitude and the number of circulation by analyzing the process of the most dangerous element stress with the rain flow method and calculated the fatigue life of the windbreak based on the linear cumulative damage Miner theory by compiling the procedure of Ansys wind-induced fatigue. The fatigue life was calculated when the designed wind speed respectively is 32.9 m/s, 26.8 m/s, 20 m/s, and 12 m/s.