【作者】 白那；

【导师】 张文福；

【作者基本信息】 大庆石油学院 ， 防灾减灾工程及防护工程， 2004， 硕士

【摘要】 网架结构是一种较好的大跨度屋盖结构形式。它具有空间受力、节省钢材、空间刚度大、建筑高度小、便于工业化、定型化、建筑造型美观等优点，在国内外的人型体育馆、停机场、中型练习馆、展览馆、俱乐部、剧院、食堂以及工业厂房等工程的屋盖结构中以得到广泛应用。然而，随着地震等自然灾害的逐年频繁发生，如何进行网架结构的抗震设计仍是为人们所关心的重要问题。 本文主要研究平板型周边支承正放四角锥网架的固有振动规律和竖向地震作用。 主要研究工作为： 第1部分．本部分对有限元理论一般原理及有限元分析软件ANSYS的功能、典型分析问题的过程进行了简要的介绍。给出了确定网架有限元模型几何参数应遵循的一般原则，并依据《网架结构设计与施工规程》中网架内力计算算法编制了计算周边简支条件下正放四角锥网架内力和杆件截面F90程序，从而确定采用ANSYS进行网架计算所需的单元实常数。编制了生成正放四角锥网架节点、单元编号及约束信息的F90程序，实现了用命令流输入的方法生成正放四角锥网架的有限元模型，为后面研究网架自由振动规律及竖向地震响应奠定了基础。通过算例比较《规程》算法与ANSYS计算结果，表明本文采用ANSYS软件建立网架有限元模型的方法是正确的，同时也证明了《规程》网架内力算法在精度方面是比较高的。 第2部分．给出了网架固有振动频率的拟夹层板法算法和ANSYS模态分析算法。阐述了模态分析的实现过程，并对模态分析所采用的子空间迭代法原理进行了简要的介绍。通过对拟夹层板法和ANSYS模态分析的比较，表明了拟夹层板法作为一种简化的计算方法，其精度是比较高的，同时也证明了采用ANSYS软件进行网架自振特性研究的可靠性，在此基础上采用ANSYS模态分析对网架固有振动特性进行了研究。通过对44种网架自由振动频率的分析，得出了网架自由振动的一般规律，确定了网架自由振动频率的影响因素。 第3部分．本部分主要对正放四角锥网架结构的竖向地震作用进行了研究。介绍了网架在地震作用下的几种计算方法，对水平地震反应谱的确定及如何利用水平地震反应谱确定竖向地震反应谱进行了阐述，并对竖向地震反应谱的数值进行了转换，这也是利用ANSYS软件进行竖向地震反应谱分析的关键。该部分还简要的阐述了利用ANSYS软件进行谱分析的步骤，并结合具体实例给出了利用ANSYS软什进行谱分析的命令流语句。在此基础上本文对Ⅱ类场地上的正放四角锥网架进行的地震作用分析，得出了正放四角锥网架的竖向地震内力分布规律。 第4部分．在前面工作的基础上，通过对15种正放四角锥网架竖向地震内力系数的研究，找出最大竖向地震内力系数与第一阶竖向振型频率的内在联系，从而建立了计算正放四角锥网架竖向地震内力的实用计算方法，并进行了验证。本文研究为《抗震规范》、《网架结构设计与施工规程》的修订提供理论依据。更多还原

【Abstract】 Space grid is a sort of preferable roof type for long span buildings. It has many advantages, for example forces are transferred in a 3D manner, save steel material, large rigidity, small building highness, industrialized, beauty sculpt ect. There are tremendous buildings adopt space grid structure as roof domestic and abroad, including big gymnasium, airdrome, middle training house, exhibition hall, club , showplace, dinning hall and industry workshop. However, how to perform seismic design of space grids is still an important problem concerned, because disaster as earthquake happen very frequently in recent years.The rule of free vibration and vertical seismic action of pyrimid space grid(PSG) roof structures are studied in this paper.Part 1. Finite element theory, functions of ANSYS software and typical analysis process are introduce in this part. Principals of how to ensure geometry parameter of space grids finite element model are given and F90 program to calculate member force and chord section is developed according <<Space Grid design and construction code>> (SGDC code) so as to determine the real constant ANSYS needed. To create finite element model of PSGs, program to create node, element number and restriction information is compiled also. Comparison between <<SGDC code>> method and ANSYS is carried out, and results show that the method to create PSG finite element model by ANSYS is correct and the simplified method given by <<SGDC code>> to calculate chord force is of high accuracy in precision.Part 2. Equivalent sandwich plate and ANSYS modal analysis are used in the calculation of free vibration. The process of modal analysis and the subspace alternate theory are introduced. Comparison results show that as a simplified method equivalent sandwich plate method is accurate in precision. It also proved the study of free vibration property of space grids adopt ANSYS software is reliable. The dynamic property of PSG is studied through free vibration analysis. Through free vibration frequencies analysis of 44 PSGs, the general rule of PSGs is achieved and influence factors for PSGs are determined.Part 3. Vertical seismic action of PSG is studied in this part and calculation method of seismic action are introduced. The method of how to determine vertical seismic spectrum by horizontal seismic spectrum is introduced also in this part. Vertical seismic spectrum curve values are transformed so that it can be adopted by ANSYS spectrum analysis. The procedures of spectrum analysis are given. Through the seismic action analysis of PSGs on II ground, we achieve the distribution rule of seismic internal force coefficients. Part 4 . The inherent relationship between vertical seismic internal force coefficient max and the first vertical frequency is found by researching seismicinternal force coefficients of 15 kinds of PSGs, then practical calculation methods for pyramid space grids is determined, and testifying is also carried out.更多还原