网架结构在地震下的失效模式及其数值表述
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摘要
通过对地震作用下不同形式的网架结构进行大规模数值计算,以最大节点位移超过结构跨度的1/50为失效准则,分析了其动力失效模式及特征,将决定网架结构动力失效模式的因素提炼为四个方面:结构8P杆件比例、全时程的最大位移、平均单杆塑性应变能以及临失效前平均位移与最大位移的比值。由于网架结构各失效模式之间存在模糊性,利用模糊C-均值方法分析以上四个因素,进而将网架动力失效模式归为三类:失稳型局部失效、强度型整体失效和强度型局部失效。结果表明,模糊C-均值方法可以有效地划分网架结构的失效模式,并将自然语言描述的失效模式转变为数字语言的表述,得到各失效模式的典型数字特征,可用于识别其他网架结构,为结构的性能化设计打下基础。
Based on large-scale numerical calculations for different forms of grid structures subjected to earthquake,dynamic failure modes and characteristics were analyzed,assuming the failure criterion is that the maximum displacement exceeds 1/50 of the span.Dynamic failure modes of grid structures are determined by four factors: the proportion of 8P bar,the maximum displacement during full-time history,the average plastic strain energy,and the ratio of the average to maximum displacement before expiration.As the failure mode is fuzzy,the four factors were analyzed using fuzzy C-means method,and the failure modes were classified into three categories: instability-based progressive collapse,strength-based overall collapse and strength-based progressive collapse,which are described by natural and numerical language respectively.The results show that fuzzy C-means method can effectively classify the failure modes of grid structures,and transform the description from natural to numerical.The numerical prototypes of failure modes were obtained,which can be used to recognize other unknown types of grids,and lay the foundation for performance-based design.
Based on large-scale numerical calculations for different forms of grid structures subjected to earthquake,dynamic failure modes and characteristics were analyzed,assuming the failure criterion is that the maximum displacement exceeds 1/50 of the span.Dynamic failure modes of grid structures are determined by four factors: the proportion of 8P bar,the maximum displacement during full-time history,the average plastic strain energy,and the ratio of the average to maximum displacement before expiration.As the failure mode is fuzzy,the four factors were analyzed using fuzzy C-means method,and the failure modes were classified into three categories: instability-based progressive collapse,strength-based overall collapse and strength-based progressive collapse,which are described by natural and numerical language respectively.The results show that fuzzy C-means method can effectively classify the failure modes of grid structures,and transform the description from natural to numerical.The numerical prototypes of failure modes were obtained,which can be used to recognize other unknown types of grids,and lay the foundation for performance-based design.
引文
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[11]Mingoti S A,Lima J O.Comparing SOM neural network withFuzzy c-means,K-means and traditional hierarchicalclustering algorithms[J].European Journal of OperationalResearch,2006,(174):1742-1759.
[12]Bezdek J C.Pattern recognition with fuzzy objective functionalgorithms[M].Plenum Press,New York,1981.
[2]王晓可,范峰,支旭东,等.单层柱面网壳在强震下的破坏机理研究[J].土木工程学报,2006,39(11):26-32.
[3]杜文风,高博青,董石麟,等.一种判定杆系结构动力稳定的新方法——应力变化率法[J].浙江大学学报(工学版),2006,40(3):506-510.
[4]杜文风,高博青,董石麟.单层网壳动力失效的形式与特征研究[J].工程力学,2009,26(7):39-46.
[5]沈斌.网架结构倒塌破坏机理研究[D].天津:天津大学,2007:25-43.
[6]丁阳,郭峰,李忠献.地震作用下空间网架结构考虑损伤累积效应的弹塑性分析[J].工程力学,2005,22(1):54-58.
[7]钱稼茹,张微敬,朱丹,等.北京A380机库结构地震反应分析[J].土木工程学报,2008,41(2):9-16.
[8]周玉新,周志芳,孙其国.岩体结构面产状的综合模糊聚类分析[J].岩石力学与工程学报,2005,24(13):2283-2287.
[9]樊哲超,陈建生,董海洲,等.模糊聚类方法研究堤坝渗漏[J].岩土力学,2006,27(7):1214-1218.
[10]Toprak S,Nacaroglu E,Cetin O A,et al.Pipeline damageassessment using cluster analysis[J].TCLEE 2009:LifelineEarthquake Engineering in a Multihazard Environment,2009ASCE.
[11]Mingoti S A,Lima J O.Comparing SOM neural network withFuzzy c-means,K-means and traditional hierarchicalclustering algorithms[J].European Journal of OperationalResearch,2006,(174):1742-1759.
[12]Bezdek J C.Pattern recognition with fuzzy objective functionalgorithms[M].Plenum Press,New York,1981.
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