超大型冷却塔抗震薄弱部分分析及加强措施

Seismic Analysis and Strengthening Methods for Weak Parts of a Supersized Cooling Tower

对于大型复杂结构,为节省计算工作量,通常采用宏观有限元单元对构件进行模拟,这样虽然可以把握结构的整体受力性能,却不能清楚地了解薄弱部位的局部受力情况。在对某超大型冷却塔进行整体有限元分析的基础上,将结构的薄弱部位取出,对其进行精细的子结构有限元分析。根据整体结构弹性和弹塑性时程分析结果,发现该超大型冷却塔的变形集中在人字形支柱,且其变形值接近其变形能力限值;通过子结构细部分析,发现人字形支柱两端是最为薄弱的部位,因此提出采用外包钢管法对柱两端进行加固。外包钢管加固可以较大程度地提高混凝土柱的承载能力和延性。在相同受力情况下,加固柱的混凝土受压损伤、箍筋应力和应变等较未加固柱大幅减小。

In order to save workload,finite element method is adopted to do macroscopic force analysis on large-scale and complex structure,but it is unable to clarify the force situation of local weak parts of structure.This paper using finite element method conducted delicate analysis on weak parts of a supersized cooling tower based on results of global analysis of whole structure.According to the result of elastic analysis and elastic-plastic time history analysis,deformations of this cooling tower are concentrated at Y-shaped pillars,and close to allowable deformation limit.It is revealed that both ends of Y-shaped pillars are the weakest parts of whole structure.Steel tube encasement is adopted to reinforce ends of columns,which significantly raises capacity and ductility of concrete columns.Under the same load condition,the compressive damage,stress and strain of stirrups are considerably reduced compared with the unreinforced columns.