摘要
钢筋混凝土双曲线冷却塔由于施工误差、混凝土长期徐变或收缩将产生不同程度的几何缺陷.为了解子午向几何缺陷对双曲线冷却塔结构性能的影响,采用有限元分析软件ANSYS对产生缺陷前、后2种模型进行各种工况下的计算对比,分析该缺陷对结构动力特性、静力特性及稳定性的影响.计算结果表明,子午向的几何缺陷提高了结构的水平抗侧刚度,提高了一阶振动频率,减小了结构在水平荷载下的变形;在风荷载或自重作用下,缺陷部位均发生应力集中现象.荷载组合后的计算结果表明,环向轴力和子午向弯矩增大,而环向弯矩和子午向轴力变化较小;缺陷对温度作用下结构的性能几乎没有影响.按规范进行的稳定分析表明,缺陷极大地降低了塔筒的局部稳定安全系数.但是特征值屈曲分析表明,在塔筒喉部半径缩小后,在水平荷载作用下的屈曲系数有所提高,而在竖向荷载下的屈曲系数有所降低,双曲线形状的改变对塔筒在不同方向荷载下的屈曲具有不同的影响效果.
The reinforced concrete hyperbolic cooling tower may have geometric imperfections,which stem from construction errors,the effect of creep/shrinkage of concrete,service loads,and so on.In order to investigate the influence of meridional geometric imperfections on hyperbolic cooling towers,two models,the perfect model and the constructed model,were analyzed by software ANSYS under various load cases to illustrate the structural performance,such as dynamic characteristics,static behaviors and stability.The results reveal that,the meridional geometric imperfections increase the lateral stiffness,enlarge the primary natural frequency and reduce the displacement under horizontal loads.In the vicinity of imperfections,stress concentration phenomenon is found under wind load or self-weight.In addition,according to the results of load combination,both hoop forces and meridional bending moments are augmented while hoop bending moments and meridional forces vary slightly.And temperature-induced structural performance is not sensitive to the imperfections.From the formulation in the national code,the local elastic buckling factor of the shell is reduced remarkably.Meanwhile,eigenvalue buckling analysis reflects that the buckling factor is increased under wind load while reduced under self-weight,i.e.,the deviation of hyperbolic curve produces different buckling features due to different kinds of loads.
出处
《浙江大学学报（工学版）》
EI
CAS
CSCD
北大核心
2010年第4期819-825,共7页
Journal of Zhejiang University：Engineering Science
关键词
双曲线冷却塔
几何缺陷
静力特性
动力特性
稳定性
hyperbolic cooling tower
geometric imperfection
static behaviors
dynamic characteristics
stability
