土-结构动力相互作用及基础形式对超大型冷却塔结构地震反应的影响分析

采用ABAQUS有限元分析软件,分别对基于刚性地基假定的环板基础、考虑土-结构动力相互作用的环板基础和桩基础超大型冷却塔模型进行了模态分析、弹性和弹塑性时程分析,研究了土-结构动力相互作用和基础形式对超大型冷却塔结构动力特性和地震反应的影响。结果表明:当考虑相同阶数的振型时,刚性地基模型的振型参与质量系数最小。地震作用下,刚性地基模型和桩基础模型的加速度响应、支柱内力、塔壳混凝土主应力等一般比考虑土-结构动力相互作用的环板基础模型偏大,但塔顶水平位移偏小。土-结构动力相互作用比基础形式对冷却塔动力特性以及地震反应的影响更大,且二者对冷却塔竖向振动的影响比水平向大。三种模型计算所获得的冷却塔薄弱部位均集中于支柱,且支柱最大侧移角相差不大。

Effect of Soil-structure Interaction and Foundation Type on Seismic Response of Super-large Cooling Tower

Modal analysis,elastic and elastic-plastic time history analysis were carried out by ABAQUS software for three super large cooling tower models,which are the model with rigid foundation assumption,the models with annular plate foundation and pile foundation considering soil-structure interaction,to investigate the effects of soil-structure interaction and foundation type on the dynamic characteristic and seismic response of the super large cooling tower.The results showed that the modal participating mass ratio of the rigid foundation model is the minimum,compared to other modelswith the same amount of modals included.Under earthquake excitation,the acceleration response,internal force in columns,concrete principle stress of the tower shell of the rigid foundation model and pile foundation model is higher than that of the annular plate foundation model considering soil-structure interaction,but the horizontal displacement at the top of the tower is smaller than that of the later.The effects of soil-structure interaction is more significant than that of foundation types on the dynamic characteristic and seismic response of the super-large cooling tower,also the two factors have greater effects on the vertical vibration than the horizontal vibration.The weak parts in the three models all concentrated on the columns,and the maximum drift angles of the columns in the three models are closed.