弦支穹顶初始几何缺陷分布及稳定安全系数取值研究

Research on initial geometric imperfection distribution and stability safety factor of suspen-dome

根据河北北方学院体育馆项目建立模型,利用MIDAS有限元软件分析弦支穹顶结构在自重及预拉力作用下的初始受力状态.利用ABAQUS有限元软件对弦支穹顶结构进行全过程分析,研究其考虑几何非线性、材料非线性的稳定性能,提出适用于弦支穹顶的初始几何缺陷施加方法和只进行几何非线性全过程分析时的安全系数取值,量化材料非线性对稳定极限承载力的影响.结果表明,从工程设计角度出发,建议采用N阶特征缺陷模态法(N取20),取其最小值作为稳定承载力;当大跨度扁平弦支穹顶结构由稳定承载力控制时,宜进行弹塑性稳定分析,按弹塑性稳定极限承载力安全系数2.0进行设计优化.

The models are set up according to the project of Hebei North University Gymnasium.By using the finite element software MIDAS,the initial stress state of suspen-dome models under the conditions of dead load and pretension is analyzed.Then based on the finite element software ABAQUS,a whole process analysis is conducted to study the stability performance considering geometric nonlinearity and material nonlinearity.Through the whole process analysis,an initial geometric imperfection method which is suitable for suspen-dome structures and the stability safety factor considering geometric nonlinearity are proposed,and the influence of material nonlinearity on the stability bearing capacity is quantified.It is shown that,from the perspective of engineering design,the N-order eigenvalue imperfection mode method which takes the minimum value of the first 20 orders as the stability bearing capacity is reasonable.When the design of large-span flat suspen-dome is controlled by stability bearing capacity,it is appropriate to optimize the design according to the safety factor of 2.0 for the elasto-plastic stability bearing capacity.