工程网架结构参数化建模和动力特性分析设计

工程网架结构参数化建模和动力特性分析

摘要

网架结构是较好的大跨度屋盖结构形式，具有空间受力、刚度大、节省钢材、抗振性能好、建筑高度较小、造型美观等。目前，已有大型体育馆、展览厅、影剧院、工业厂房、仓库等千余座工程的屋盖采用网架结构，其广泛的应用前景促使人们对其展开深入研究。本课题就是将体育馆网架结构简化为双层网架结构模型，通过有限元软件ANSYS对其进行分析对计算结果的分析提出结构改进方案，对验证原设计和指导设计修改有重大的意义。

在本课题中通过有限元分析软件自带的APDL语言实现网架的参数化建模，施加约束及加载，可以很有效的缩短网架的建模的时间，简化了网架的建模过程。

通过ANSYS对网架在两种不同的支承情况下的静力分析进行比较，可发现网架的变形规律即网架的变形在X、Y、Z 方向都会交替出现，但在Z方向为主要变形。同时杆件的内力分布得出了不同约束时产生了变号，从而在工程实际施工中应给予考虑。

用模态分析确定了网架结构的十阶模态振型及固有频率，便可以在设计与改进时使网架结构的固有频率避开其在使用过程中的外部激振频率。同时为之后的谱响应分析奠定基础。

通过进一步的随机振动谱分析，采用地震波对网架结构进行计算，找出危险点的响应频率，从而使网架在工程实际情况中避免易产生共振的频率即网架的低阶频率。

[关键词]：双层网架；有限元法；静力分析；模态分析；谱分析

Abstrat

Grid structure is a good large-span roof structure, with space force, stiffness, to save steel and anti-vibration performance and the height of the building smaller and the shape of aesthetics, etc. At present, there are large stadium, exhibition hall, theaters, industrial plants Block, thousands of warehouse roof using the network structure, it is widely used to promote it，s conduct in-depth studies. This subject is about making grid structure of gymnasium simplify to double-layer grids model,using finite element software ANSYS to analysis,then pose the plan of improved structure according to the results .It has great meaning to test originaldesign and guide design modify.

In self simultaneous APDL language realizes the net rack among the problem by the fact that finite element method analyses a software parameterization build a model, Exert constraint and loading , can be effective shortening the process having covered the time building a model as with a net , having simplified covering a rack as with a net to build a model.

Analyse the comparison being in progress by the fact that ANSYS puts up static force under two kinds different supporting condition to the net, Network can be found deformation that the grid deformation in X, Y, Z direction will take turns, But in Z direction as the main deformation. Meanwhile bar distribution of internal forces come to different constraints arising from the change, so the actual construction works should be considered.

Using modal analysis to determine the grid structure of the 10-modal shape and natural frequency, we will be able to design and make improvements to the grid structure to avoid its natural frequency in the course of the external excitation frequency. After the same time as the harmonic response lay the foundation for analysis.

Through further random vibration spectrum analysis, seismic wave of network structure, identify dangerous spots response frequency, so that the network in practical situations to avoid easy resonance frequency that grid of the lower frequency.