【作者】 董煜；

【导师】 韩庆华；

【作者基本信息】 天津大学 ， 结构工程， 2010， 硕士

【摘要】 近年来,立体桁架结构越来越多的被应用在航站楼、火车站及体育场馆等大型公共建筑,悬挑型立体桁架则主要被应用于体育场。稳定性能是影响钢结构承载能力的一个关键因素,而现行规范对立体桁架在平面外的整体稳定性并没有统一的规定,因此,对立体桁架在平面外稳定性能的研究很有意义。本文首先将悬挑立体桁架简化为闭口薄壁悬臂梁模型,采用能量法建立微分方程,求出该结构在平面外稳定临界荷载的近似解析解,并将其与简化模型的强度临界荷载进行对比,以获得悬挑立体桁架极限荷载由强度控制而不发生平面外失稳的条件。随后,采用有限元方法通过大量计算分析立体桁架各截面几何参数对平面外稳定性能的影响,并将其与解析解的结论进行对比。最后,采用有限元方法分析悬挑立体桁架在地震作用下的动力稳定性。研究表明:上、下弦杆截面面积对悬挑立体桁架平面外的稳定性影响不大,随着斜腹杆截面面积的增大,立体桁架面外稳定性增强;当节间长度等于截面高度时,悬挑立体桁架的平面外稳定性最好;对每个选定的高挑比h l,都存在一个临界截面宽高比b h,当h l≥110时,临界截面宽高比可取为b h < 1 2.5,当1 20 < h l< 1 10时,临界截面宽高比可取为b h < 1 2, h l不宜小于1 20;悬挑仰角在工程常用角度范围内对悬挑立体桁架平面外稳定的影响不大。更多还原

【Abstract】 In recent years, the tube-truss structure is applied more and more in large public buildings, e.g. the terminal, the railway station, and the sports stadium etc., and the cantilever tube-truss structure is mainly applied in the sports stadium. Stability is a key factor which could affect the carrying capacity of steel structure, however, there is no provision about the out-plane stability of tube-truss structure, so it is meaningful that the out-plane stability of tube-truss structure is studied in this paper.Firstly, the tube-truss structure is simplified to a model of thin-walled closed cantilever, then the differential equations are established by the energy law, and the approximate analytical solution of out-plane stability ultimate load is obtained. Compared to out-plane stability ultimate load and strength ultimate load, this paper obtain the condition that the cantilever tube-truss structure couldn’t lose the out-plane stability. Secondly, the impact of geometric parameters on the out-plane stability of tube-truss structure is analyzed by the finite element method, and then, it is compared with the conclusions of analytical solution. Finally, the dynamic stability of cantilever tube-truss structure under earthquake is also analyzed by the element method.The study indicates the following conclusions: the top chords and bottom chords have little impact on the out-plane stability of tube-truss structure, although with the increase of belly bar’s section area, the out-plane stability of tube-truss structure increase; when the internode length equals to the section height, the out-plane stability of cantilever tube-truss structure would be best; for each h/l, there is a critical aspect ratio b/h, when h / l 1/10, the critical aspect ratio b / h < 1/ 2.5, when 1/ 20 < h / l< 1/10, the critical aspect ratio b / h < 1/ 2, and h / l< 1/ 20 is inappropriate; within the range commonly used in engineering, the elevation has little impact on the out-plane stability of cantilever tube-truss structure.更多还原