纤维模型中的不同因素对钢框架抗连续倒塌非线性静力分析的影响
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摘要
基于纤维模型,使用Opensees有限元软件分别讨论不同类型的单元、构件划分单元数、单元积分点数和截面纤维划分情况等不同因素对平面钢框架进行抗连续倒塌非线性静力分析的影响,并将其计算结果与在Abaqus中建立实体单元模型分析的结果进行对比。以一个2层2跨的平面钢框架为例进行分析,结果表明:利用基于柔度法的梁柱单元(FB单元)和基于柔度法的塑性铰单元(FBP单元)可以得到较好结果,但由于FBP单元需要设置塑性区的长度,同时考虑到使用的方便性,所以选择使用FB单元进行后续分析。对于FB单元,一个构件划分1个单元,每个单元设置6个积分点,且梁柱截面的翼缘和腹板划分为5×1的纤维数,这样既可以提高计算效率,也可满足计算的精度要求。
Based on the fiber model,the impact of different factors such as different types of elements,element number of element divisions,number of element integral points and cross-section fiber division etc. on the nonlinear static analysis for progressive collapse resistance of steel frames is discussed using finite element software Opensees.The results from Opensees are compared with the results from Abaqus after building solid element model. Taking a two-story,two-span plane steel frame as the analysis example,the results show that better results can be obtained with the Force-Based Beam-Column Elements( FB elements) and the Force-Based Plastic hinge elements( FBP elements). However,since the length of the plastic zone is needed in FBP elements,the FB elements are chosen for subsequent analysis in order to achieve convenience by the same token. For the FB elements,one member is divided into 1 element and the number of integration points for each element is set as 6,and the number of fibers of the beam and column cross-section flanges and webs using H-beam is divided into 5 × 1,which can improve the calculation efficiency and also meet the accuracy requirements of the calculation.
Based on the fiber model,the impact of different factors such as different types of elements,element number of element divisions,number of element integral points and cross-section fiber division etc. on the nonlinear static analysis for progressive collapse resistance of steel frames is discussed using finite element software Opensees.The results from Opensees are compared with the results from Abaqus after building solid element model. Taking a two-story,two-span plane steel frame as the analysis example,the results show that better results can be obtained with the Force-Based Beam-Column Elements( FB elements) and the Force-Based Plastic hinge elements( FBP elements). However,since the length of the plastic zone is needed in FBP elements,the FB elements are chosen for subsequent analysis in order to achieve convenience by the same token. For the FB elements,one member is divided into 1 element and the number of integration points for each element is set as 6,and the number of fibers of the beam and column cross-section flanges and webs using H-beam is divided into 5 × 1,which can improve the calculation efficiency and also meet the accuracy requirements of the calculation.
引文
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[2] BS EN 1991-1-7∶2006,Eurocode 1∶actions on structures—Part 1-7∶general actions—accidental actions[S].
[3] CECS 392∶2014.建筑结构抗倒塌设计规范[S].
[4]陆金钰,舒赣平,包永成.基于柔度法单元的钢框架结构连续倒塌分析[J].东南大学学报(自然科学版),2015,45(4)∶763-768.
[5]刘传卿,梅佐云,孙海峰.基于纤维模型的钢框架连续倒塌抗力机制分析[J].防灾减灾工程学报,2013,33(4)∶424-429.
[6] Hyun-Su Kim,Jinkoo Kim,Da-Woon An. Development of integrated system for progressive collapse analysis of building structures considering dynamic effects[J]. Advances in Engineering Software,2008,40(1)∶1-8.
[7]杜轲,孙景江,许卫晓.纤维模型中单元、截面及纤维划分问题研究[J].地震工程与工程振动,2012,32(5)∶39-46.
[8]谢甫哲,舒赣平.钢框架连续倒塌的模拟方法研究[J].工程力学,2011,28(10)∶34-40.
[9] GB 50017—2017.钢结构设计标准[S].
[10] GSA. Progressive collapse analysis and design guidelines for new federal office buildings and major modernization projects[S]. USA∶United States General Services Administration(GSA),2005.
[11]刘观云.多层钢结构住宅结构体系及梁柱节点的研究[D].长沙∶中南大学,2008.
[12]陈学伟,林哲.结构弹塑性分析程序OpenSEES原理与实例[M].中国建筑工业出版社,2014.
[13] Filippou F C,Neuenhofer A. Evaluation of nonlinear frame finite-element models[J]. Journal of Structural Engineering,1997,123(7)∶958-966.
[14] Scott M H,Fenves G L. Plastic Hinge Integration Methods for Force-Based Beam–Column Elements[J]. Journal of Structural Engineering,2006,132(2)∶244-252.
[15]李文杰.考虑分布塑性的纤维模型在框剪结构Pushover分析中的应用[D].广州∶华南农业大学,2004.
[16]姜锐,苏小卒.塑性铰长度经验公式的比较研究[J].工业建筑,2008(S1)∶425-430.