超大型冷却塔结构风振与地震作用影响比较

柯世堂^1,2, 赵林^1,2, 葛耀君^1,2

1.同济大学土木工程防灾国家重点实验室;2.同济大学土木工程学院



摘要:

超大型冷却塔属于典型风及地震敏感结构,随着塔高的日益增大这两种作用成为设计的控制因素,为了研究这两种作用在不同部位的控制程度,对某超大型冷却塔进行风洞刚体测压和气弹测振试验,通过加载试验获得的塔筒表面风压分布模式和风振系数进行风载作用下结构响应计算,和冷却塔在七度地震作用下的响应进行比较.对比结果表明:环基和塔筒响应完全受风振控制,其在风载作用下的内力数值远大于地震作用下的数值,其中子午向和环向内力从塔底到塔顶逐渐变小,子午向和环向弯矩最大值均出现在塔筒的中部区域.两者对于人字柱的内力影响相差较小,和自重作用共同控制人字柱响应;采用振型分解法计算结构响应需要考虑前300阶的振型影响,而对于风振作用的频域分析只需考虑前30阶模态数即可满足.

关键词:  冷却塔  风洞试验  地震作用  参振模态

DOI：10.11918/j.issn.0367-6234.2010.10.025

分类号:TM753

基金项目:国家自然科学基金委重大研究计划重点研究项目(90715039);科技部重大科技项目(2008ZX06004-001)



Comparison of super-large cooling towers under earthquake excitation and wind load

KE Shi-tang^1,2, ZHAO Lin^1,2, GE Yao-jun^1,2

1.State Key Laboratory for Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;2.College of Civil Engineerin,Tongji University,Shanghai 200092,China)

Abstract:

In order to research the influence of super-large cooling tower under earthquake excitation and wind load,the rigid model and aero-elastic model of a super-large cooling tower in the wind tunnel were employed,the data obtained in the test were loaded to calculate the structural response.By the comparison with the response under earthquake excitation,it is obvious that the responses of annular base and tower shell are completely controlled by wind load,and the value under wind load is much greater than that under earthquake excitation.Vertical and hoop forces of tower shell are diminished from the bottom to the top,and the maximums are found at the middle of the tower shell.Their influence on supporting columns is not obvious.300 modes should be considered in mode analysis method,while 30 modes are only considered when the structural response is calculated under wind load.

Key words:  cooling tower  wind tunnel test  earthquake excitation  modes of vibration