【作者】 张健；

【导师】 姜正荣； 夏绍全；

【作者基本信息】 华南理工大学 ， 建筑与土木工程（专业学位）， 2016， 硕士

【摘要】 单双层网壳是由单层网壳和双层网壳组合而成的空间结构体系,近年来得到了广泛的应用。目前,对单层或双层网壳结构的静、动力性能的研究已取得了丰硕的成果,但对单双层网壳结构的相关研究相对较少。本文以某实际工程双层网壳结构及由之发展而来的六个单双层网壳结构为研究对象,对其进行静、动力分析,主要工作如下:(1)对两类结构进行静力分析,并改变参数,探讨活载的半跨分布、单双层连接处节点形式等因素对单双层网壳结构的影响。研究表明:单双层网壳竖向位移最大对应节点均靠近单双层连接处,且结构刚度随单层区域跨度的增大而减弱;由于单双层连接处刚度突变,节点竖向位移和环向杆轴力均在此处突变,其变化幅度随单层区域跨度增大而增大;活载的半跨分布对节点竖向位移、环向杆轴力起控制作用;改变单双层连接处节点形式对结构静力特性的影响很小。(2)在静力分析的基础上,对两类结构的稳定性能进行研究,分别考察几何和材料非线性对结构稳定承载力的影响程度,进一步探讨参数改变和不同缺陷引入方式对单双层网壳结构的影响,并对特征缺陷模态法的适用性及单双层网壳的缺陷敏感区域进行了研究。分析表明:几何非线性对理想的双层及单双层网壳稳定承载力的影响程度随单层区域跨度的增大而增大,而材料非线性与此相反;综合考虑结构的经济性和稳定性要求,建议单层区域跨度不宜超过结构跨度L的40%;活载的半跨分布对单双层网壳结构的稳定承载力起控制作用,改变单双层连接处节点的形式可有效改善其稳定性能;结构对初始几何缺陷的变化非常敏感,当单层区域跨度占比较小时,初始几何缺陷最大计算值取L/400较合理,当单层区域跨度占比较大时,取L/500较合理;单双层网壳结构的缺陷敏感区域主要位于单层区域(含单双层连接处)。(3)针对不同地震波引入方式及地震波选取对单双层网壳结构动力响应的影响进行了对比研究,此外,对不同初始几何缺陷引入方式进行了探讨。结果表明:支座大质量法能更有效地评估结构位移响应的变化,建议工程实践中,对此类结构的动力响应分析宜采用支座大质量法;相对于常规记录地震波,采用适合特定场地及基本周期频段的最不利地震动所得的动力响应更不利;以随机缺陷模态法为基准,对特征缺陷模态法和自振缺陷模态法进行对比分析,特征缺陷模态法计算结果偏安全,且保证率较高,而以自振模态作为初始几何缺陷的分布模式更合理,但结果偏于不安全。更多还原

【Abstract】 The single-double layer reticulated shell, which has been widely used in recent years, is a spatial structure composed of single layer one and double layer one. Currently, fruitful results have been obtained by many researchers on static and dynamic stability characteristics of single layer reticulated shell or double layer one, however it’s lack of systematical study about stability characteristics of single-double one. This paper will use a double layer reticulated shell based on actual project and six single-double layer ones which are extended from the double layer one as the research projects, compute and analyze the static and dynamic characteristics of single-double layer one. The main contents are summarized as follows:(1) This paper investigates the static behaviors of two kinds of structure respectively, on this basis, the influences of parameter change on single-double layer reticulated shell,which include half-span distribution of live loads and changing form of the joint node of single-double layer, are studied. The results show that the nodes where the maximum vertical displacement happens are close to the joint of single-double layer, and the stiffness of structure declines with the enlargement of single layer region span. Besides, both the node vertical displacement and the axial force of circle members change violently due to the stiffness mutation located in the joint of single-double layer, and the change rate also increases with the augment of single layer region span. Furthermore, both the node vertical displacement and the axial force of circle members are controlled by half-span distribution of live loads, and changing form of the joint node of single-double layer have little effect on the structural static behaviors.(2) On the basis of static analysis, the analysis of impact of geometric nonlinearity and material nonlinearity on two kinds of structure was performed, as well as probing the effects on stability by several parameters and different initial geometric imperfection modes. Besides, the applicability of eigenvalue imperfection mode method is discussed. At last, this paper studied the imperfection sensitive region of single-double layer reticulated shells. The research shows that along with the augment of single layer region span, the impact of geometric nonlinearity on the stability bearing capacity of the perfect double and single-double layer reticulated shell increases, on the contrary, the impact of material nonlinearity declines. It’s suggested that the ratio of single layer region span should not exceed 40 percent of structural span based on the considerations of economy and stability. In addition, the stability bearing capacity of single-double layer reticulated shell is more conservative under the half-span distribution of live loads and can be improved obviously by changing form of the joint node of single-double layer. Furthermore, the structure is sensitive to the variation of initial geometric imperfection, a 1/500 of span as the reasonable maximum value of imperfection is more suitable for large single layer region span ratio, and 1/400 of span for small single layer region span ratio. In the end, the structural imperfection sensitive region locates primarily in single layer region(including the joint of single-double layer).(3) This paper compares the effects of different seismic wave simulation modes and different seismic waves on the structural dynamic response of single-double layer reticulated shell, and also studies initial geometric imperfection modes. The research shows the following three conclusions. Firstly, the variation of structural dynamic response can be measured more effectively by support large mass method, so this method is suggested to be a better method to calculate structural dynamic response. Secondly, compared with the conventional seismic wave records, the dynamic response is more adverse when the severest ground motion which meet certain site and basic period band are adopted. Lastly, when using stochastic imperfection modal method as the baseline reference, although taking structural natural vibration mode as initial geometric imperfection mode is more reasonable, the results of this method are less securable. By contrast, not only it shows a tendency to safety when using eigenvalue imperfection mode method, but the assurance rate of this method is higher.更多还原