超大型冷却塔钢管混凝土交叉支柱截面选型研究

Study on selection of concrete-filled steel tubular X-column in large-scale cooling tower

为解决目前超大型冷却塔工程中的钢筋混凝土交叉支柱截面尺寸大,施工周期长,施工过程中脚手架使用量大等问题,提出将钢管混凝土应用于超大型冷却塔的交叉支柱(X支柱)中。根据某实际冷却塔项目的工程特点,按照与原采用矩形钢筋混凝土X支柱方案承载力相等的原则,设计分别采用圆形钢管混凝土X支柱、长圆形钢管混凝土X支柱的结构方案;采用有限元软件ABAQUS建立采用上述3种不同截面形式(矩形钢筋混凝土、圆形和长圆形钢管混凝土)X支柱的冷却塔结构模型,并通过与实际工程自振频率实测值进行对比验证有限元模型的准确性,分析重力荷载、风荷载和地震作用下的结构响应,研究不同X支柱截面形式(截面形状和组成材料不同)对冷却塔结构性能的影响;基于纤维模型法,计算得到采用3种不同截面形式X支柱交叉区域中截面的轴力-弯矩曲线。研究结果表明:在不同的荷载作用下,圆形和长圆形钢管混凝土X支柱方案的塔筒位移均小于矩形钢筋混凝土X支柱方案的,采用钢管混凝土X支柱有利于提高冷却塔结构刚度;在承受相同轴力情况下,圆形和长圆形钢管混凝土X支柱的受弯性能均比矩形钢筋混凝土X支柱的好。根据上述分析结果,推荐采用圆形钢管混凝土X支柱。

To solve the problems of current reinforced concrete X-columns such as large cross-section size,long construction period and considerable usage of the scaffold during the construction process,it is proposed that concrete-filled steel tube(CFST)can be effectively used as the X-column in the ultra-large cooling tower project.Two types of CFST X-columns with different sections(circular section and the long-circular section)were designed and both of them had the same bearing capacity as the rectangular reinforced concrete X-column in the original scheme of prototype cooling tower project.The finite element models of the cooling tower with the aforementioned three types of X-column(i.e.,the rectangular reinforced concrete X-column,the circular and the long-circular CFST X-column),were established using ABAQUS.The accuracy of the finite element models were verified by comparing with the tested natural frequency of a practical project.The responses of structures under gravity load,wind load and earthquake action were obtained,and the influence of different cross sections of X-columns,including different cross-section shapes and material components,on the structural performance of cooling towers was studied.Finally,the axial force-moment capacity interaction curves of the aforementioned three types of X-column were obtained based on the fiber model method.The results show that the displacement of tower using circular and long-circular CFST X-column are both less than that using rectangular RC X-column under different loads,which indicates that using CFST X-column can improve the structural stiffness of the cooling tower.Under the same axial load,the bending performance of circular and long-circular CFST X-column is better than rectangular RC X-column.Based on the simulation results,the circular CFST X-column is recommended to be adopted.