【作者】 李丽；

【导师】 周绪红；

【作者基本信息】 长安大学 ， 结构工程， 2008， 硕士

【摘要】 本文在查阅相关文献的基础上,采用试验和非线性有限元分析两种方法,对低层冷弯薄壁型钢结构屋架的受力性能以及设计方法进行了研究。文中对两种不同布置形式的屋架进行了试验研究,详细介绍了试验装置、试验方法、试件的破坏过程以及对试验数据的分析处理。通过分析发现,桁架的破坏主要是支座处的破坏,杆件并未发生屈曲,说明桁架的破坏不是强度破坏,而是节点连接起控制作用。有限元分析部分对两个试件进行了模拟,同时考虑了材料非线性和几何非线性问题。采用塑性壳单元模拟桁架的弦杆和腹杆,桁架的弦杆与腹杆的自攻螺钉连接处采用耦合的方法处理,方程组求解方法由ANSYS程序自动选择。有限元分析结果与试验值吻合良好,从而证明了有限元分析方法的正确性和可行性。在此基础上,对钢材强度、截面形式,以及钢材厚度等影响桁架承载力的因素进行了参数分析,结果表明:钢材强度、截面形式,以及钢材厚度对桁架承载力都有较大的影响。本文通过柱挠度曲线法(CDC法)的计算,分析节点连接半刚性对冷弯薄壁C形钢桁架压杆计算长度的影响。通过计算分析可知,冷弯薄壁C型钢桁架压杆半刚性连接的计算长度与节点转动刚度、构件自身刚度及有效截面有关。计算了不同M ?θ曲线时柱子曲线的变化,通过对柱子曲线的对比分析,给出冷弯薄壁型钢受压杆件在平面内计算长度系数μ的建议取值。对于受压弦杆建议其计算长度系数μ= 1.0,对于受压腹杆建议计算长度系数μ= 0.9,对于端斜腹杆和端腹杆,建议其计算长度系数μ= 1.0。最后,结合已有的理论研究成果,参考国外相关的科研成果和国内结构设计方面的规范(程),对屋架进行了设计。更多还原

【Abstract】 This paper mainly presents detailed results on mechanical behavior and design method of cold-formed steel roof turss in low-rise residential structures by tests and nonlinear finite element analysis based on consulting a lot of documents.The bearing capacity of cold-formed steel roof turss about two different styles is tested in this paper. The trial device, test method and full test course as well as the analysis of test data are introduced in detail in this paper. Test results show that: the damage of test coupons happened on the supports, and the elements don’t buckling, this illustrate that test coupous don’t belong to the damage of strength, and the connection plays an important role.Nonlinear finite element analysis involving geometric large deformation and materials nonlinear is used to simulate test roof truss in this paper. Members are modeled as shell elements. The steel members are simply connected. The screws connecting of the chord to the web member are modeled through coupling methods. The equation resolution method is selected by ANSYS program automatically. The finite element analysis results are close to that of tests, so the finite element analysis method is correct. There are followed by a detailed parametric study using nonlinear finite element analyse, such as steel strength, section styles and steel thickness. The results of finite element analyse show that teel strength, section styles and steel thickness have great effect on bearing capacity of cold-formed roof truss.Based on the column deflection curve method (CDC method), the paper analysed the effect of semi-rigid connection to the effective length of compressed members in the cold-formed thin-walled steel truss. The results of CDC method show that:the influence factors of semi-rigid connection to the effective length of compressed members in the cold-formed steel truss are connection rotational stiffness, member rigidity and effective section. And the paper calculated the variety of column curve under the different M ?θcurve, at last, the suggestion value of effective length of compressed web members in cold-formed thin-walled steel truss were presented. The suggestion value of effective length of chord isμ= 1.0, The suggestion value of effective length of web member isμ= 0.9, The suggestion value of effective length of end strut and end web member isμ= 1.0.Finally, referencing above research achievements, current design codes or documents, simplified design method of cold-formed steel roof truss is done.更多还原