中文摘要：

为提高冷却塔的自振频率和抗风性能，以某大型冷却塔为例，通过增设环向加劲环或子午向加劲肋，分析了各自的尺寸、位置、数量等参数对动力特性的影响．冷却塔的动力特性主要受环向刚度控制，在适当的位置布置加劲环可以有效提高结构的频率，而子午向加劲肋则无此效果．加劲环对结构频率的提高源自结构整体振型所激发的加劲环刚度参与程度，加劲环的模态变形幅值越大，环向谐波越多，其参与度就越高，对结构频率的提高效果也越明显．实际应用中，可在塔筒中部等间距布置3—5道加劲环，这样就可以使结构频率有显著提高．

英文摘要：

To increase the frequency and improve the wind resistance properties of cooling towers, stiffening rings and ribs are added on a cooling tower, and the influences of their dimensions, locations and amounts are analyzed. The stiffening rings at an appropriate location will increase the frequency significantly, but the stiffening ribs have no such effect. The contributions of the stiffening rings to the frequency are decided by their participation degree, so the stiffening rings will have more significant effects if they are located where the mode displacement is large or the modes have more circumferential wave numbers. In practical applications, the frequency will be increased notably if there are 3-5 stiffening rings scattered along the shells with a uniform distance.