基于时变内力加权指标的大型冷却塔等效静风荷载  

Equivalent static wind loads of large cooling towers based on weighted combinations of time-variant internal forces

作　　者：赵林[1,3,4] 陈旭 展艳艳 葛耀君 ZHAO Lin;CHEN Xu;ZHAN Yan-yan;GE Yao-jun(State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;College of Civil Engineering,Shanghai Normal University,Shanghai 201418,China;Key Laboratory of Transport Industry of Wind Resistant Technology for Bridge Structures,Tongji University,Shanghai 200092,China;State Key Laboratory of Mountain Bridge and Tunnel Engineering,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]同济大学土木工程防灾国家重点实验室,上海200092 [2]上海师范大学建筑工程学院,上海201418 [3]同济大学桥梁结构抗风技术交通运输行业重点实验室,上海200092 [4]重庆交通大学省部共建山区桥梁及隧道工程国家重点实验室,重庆400074

出　　处：《振动工程学报》2021年第5期922-933,共12页Journal of Vibration Engineering

基　　金：国家重点研发计划(2018YFC0809600,2018YFC0809604);国家自然科学基金资助项目(51678451);土木工程防灾国家重点实验室自主课题(SLDRCE19-B-11)。

摘　　要：等效静风荷载是对动态风荷载和结构惯性力的拟静力化等价荷载模式,涵盖结构预期动力响应包络值,属结构设计中的荷载效应简化分析环节。在大跨空间结构抗风设计中,等效准则选取与荷载模式识别是将复杂动力问题转化为拟静力问题的关键步骤。目前等效静风荷载的评价准则众多,不同准则下的等效模式差异明显,缺少统一的共识性标准。为了体现不同风致内力响应对结构安全的综合影响,将评价准则由单一的荷载或内力层面拓展到多种内力加权组合层面。对于钢筋混凝土空间结构,该准则以物理概念清晰的配筋率作为表现形式,并融入结构动力响应时变特征。以某大型冷却塔为例,在脉动风压加载条件下进行时域分析得到风致结构动力响应时程,根据时变内力加权组合计算结构动态配筋率;从单一内力和内力加权两个层面评价现行规范等效静风荷载的抗风安全冗余度;以配筋包络线为等效目标,反演获得了兼顾多种内力加权组合的等效静风荷载分布模式,阐明了相关算法和等效策略的合理性和工程适用性。The equivalent static wind load(ESWL)is a quasi-static equivalent load model for dynamic wind loads and structural inertia forces,covering the envelope values of structural dynamic responses,which belongs to a simplified analysis of load effects in the structural design.In the wind-resistant design of large-span spatial structures,the selection of equivalent criteria and load pattern recognitions are the key steps to transform complicated dynamic loads into quasi-static ones.At present,there are a series of criteria adopted to evaluate this equivalent mode.However,ESWLs based on different criteria generally turns out to be divergent and no universal,reasonable and comprehensive ESWL evaluation standard heretofore has been widely accepted.To reflect the comprehensive influence of different internal force responses on structural safety under the action of wind,a novel evaluation criterion is therefore proposed,which further develops the existing criteria from the load or structural response to weighted combinations of internal forces.For reinforced concrete structures,the weighted internal force combination can be embodied by reinforcement ratio with a clear physical meaning and engineering application feasibility.A large cooling tower was selected to perform case studies.The time-variant wind pressure measured in wind tunnel tests was applied to the FE model.The transient dynamic analysis was conducted to calculate the time histories of wind-induced dynamic responses and to get the corresponding dynamic reinforcement ratios based on the weighted combinations of time-variant internal forces.Furthermore,the safety redundancy of traditional ESWLs defined in the present code could be evaluated on the level of single internal force and reinforcement ratio,respectively.Finally,the ESWLs based on the equivalent target of reinforcement envelope and the weighted combinations of multiple internal forces was derived,revealing rationality and convenience of the proposed algorithm.

关 键 词：大跨空间结构 风荷载 大型冷却塔 时变内力加权组合 动态配筋包络 

分 类 号：TU393.3[建筑科学—结构工程] TU312.1