【作者】 孙熙平；

【导师】 王元战；

【作者基本信息】 天津大学 ， 港口海岸与近海工程， 2008， 硕士

【摘要】 防风网是应环境保护要求而发展起来的一种新的结构型式。防风网结构在国内的应用才刚刚起步,在国内外也未见有关于它的动力响应以及风振疲劳分析的研究工作。虽然我国现已建成的防风网工程不多且规模较小,但是随着港口功能的扩展和人们环保意识的加强,大型、高效能的防风网会得到愈来愈广泛的应用。防风网结构的设计安全是面临的重要课题,特别是在风荷载作用下防风网结构的优化设计、结构动力特性、风振响应以及风振疲劳损伤等,是大型、高效能防风网结构设计需要解决的关键技术问题。本论文以某实际工程为背景,对防风网结构的设计方法,风振响应分析以及风振疲劳特性等进行了研究。本文的主要工作包括以下几个方面:1、防风网结构设计方法研究。给出了防风网结构主要设计内容、方法和步骤。设计内容主要包括:防风网总平面布置、上部钢结构设计、基础结构设计等。结合某防风网的实际工程,进行了防风网结构设计。2、风压力作用时程模拟。由《建筑结构荷载规范》中的Davenport脉动风速谱生成200s的脉动风荷载作用时程。3、防风网结构静力有限元分析。按《建筑结构荷载规范》计算等效静风压,将等效静风压作用在防风网上,利用有限元方法对防风网结构的应力、位移进行静力分析。4、防风网结构的动力特性研究。利用有限元方法计算防风网结构的频率、振型,得到防风网结构的第一阶振动频率为0.460,进一步对不同频率下防风网结构的动力响应特性进行分析。5、防风网结构动力响应研究。将由脉动风速谱生成的脉动风荷载作用时程作为输入,利用有限元方法对防风网动应力、位移响应时程进行计算。结果表明,在风动力作用下防风网结构的应力、位移有较大的放大效应。6、防风网结构风振疲劳分析。利用瞬态动力分析的结果,找出防风网结构应力疲劳最危险的地方。结合疲劳分析的基本理论,把应力时程谱转化成应力峰值谱,应用雨流法统计最危险单元的应力时程,得到应力循环次数及应力幅大小,基于Miner线性累积损伤准则编写Ansys的风振疲劳程序计算得到疲劳寿命。本文计算了设计风速为32.9 m/s、26.8 m/s、20 m/s和12 m/s时防风网结构的疲劳寿命。更多还原

【Abstract】 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.更多还原