考虑受压屈曲的圆钢管杆单元等效弹塑性滞回模型
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摘要
强震作用下网格结构杆件的破坏形式为受拉屈服和受压屈曲,而常用的理想弹塑性模型却不能考虑杆件受压屈曲的情况。使用LS-DYNA软件对不同长细比圆钢管杆单元的受压极限承载力、屈曲前后平衡路径以及卸载路径进行计算,并分析拉压往复作用下的滞回规律。通过统计这些杆单元的轴力、伸长量与长细比之间的关系,提出了一个能同时考虑受拉屈服和受压屈曲的圆钢管杆单元的等效弹塑性滞回模型。进一步将该等效弹塑性模型应用于一球面网壳结构的罕遇地震作用时程计算,发现杆件的破坏形式和结构薄弱区域与理想弹塑性模型的结果有明显区别,也反映了该等效弹塑性滞回模型的有效性。
Under strong earthquakes,the failure modes of bars in grid structures are yielding in tension and buckling in compression.However,the ideal elasto-plastic model conventionally used in seismic computation is not able to consider buckling of compressive members.By means of LS-DYNA software,the ultimate compressive loads,equilibrium paths before and after buckling,and unloading paths of steel circular-tube bars with different slenderness ratios were calculated,and their hysteretic properties under reverse tension-compression loadings were also analyzed.Based on the analysis of the statistical relationships between axial forces,axial elongations and slenderness ratios of these bar specimens,an equivalent elasto-plastic hysteretic model of steel circular-tube bar elements considering both tensile yielding and compressive buckling simultaneously was put forward.This equivalent elasto-plastic hysteretic model was further used in the time-history response computation of an illustrative lattice spherical shell under seldom occurring earthquake.The results indicated that the failure patterns of the members and the distribution of structural weak regions are obviously different from those obtained with the ideal elasto-plastic model,and the proposed equivalent elasto-plastic hysteretic model is effective.
Under strong earthquakes,the failure modes of bars in grid structures are yielding in tension and buckling in compression.However,the ideal elasto-plastic model conventionally used in seismic computation is not able to consider buckling of compressive members.By means of LS-DYNA software,the ultimate compressive loads,equilibrium paths before and after buckling,and unloading paths of steel circular-tube bars with different slenderness ratios were calculated,and their hysteretic properties under reverse tension-compression loadings were also analyzed.Based on the analysis of the statistical relationships between axial forces,axial elongations and slenderness ratios of these bar specimens,an equivalent elasto-plastic hysteretic model of steel circular-tube bar elements considering both tensile yielding and compressive buckling simultaneously was put forward.This equivalent elasto-plastic hysteretic model was further used in the time-history response computation of an illustrative lattice spherical shell under seldom occurring earthquake.The results indicated that the failure patterns of the members and the distribution of structural weak regions are obviously different from those obtained with the ideal elasto-plastic model,and the proposed equivalent elasto-plastic hysteretic model is effective.
引文
[1]中国建筑科学研究院编.2008年汶川地震建筑震害图片集[M].北京:中国建筑工业出版社,2008.
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[3]薛素铎,王建宁,曹资,等.钢网壳弹塑性地震反应分析[J].北京工业大学学报,2001,27(1):50-53.
[4]沈世钊,支旭东.球面网壳结构在强震下的失效机理[J].土木工程学报,2005,38(1):11-20.
[5]Kala Z.Sensitivity assessment of steel members undercompression[J].Engineering Structures,2009,31:1344-1348.
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[8]PEER Strong motion database[EB OL].http://peer.berkeley.edu/products/strong_ground_motion_db.html.
[2]范峰.空间网壳结构弹塑性地震响应及抗震性能分析[J].哈尔滨建筑大学学报,1999,32(1):132-37.
[3]薛素铎,王建宁,曹资,等.钢网壳弹塑性地震反应分析[J].北京工业大学学报,2001,27(1):50-53.
[4]沈世钊,支旭东.球面网壳结构在强震下的失效机理[J].土木工程学报,2005,38(1):11-20.
[5]Kala Z.Sensitivity assessment of steel members undercompression[J].Engineering Structures,2009,31:1344-1348.
[6]陈骥.钢结构稳定-理论与设计[M].北京:科学出版社,2001.
[7]夏志斌,姚谏.钢结构——原理与设计[M].北京:中国建筑工业出版社,2010.
[8]PEER Strong motion database[EB OL].http://peer.berkeley.edu/products/strong_ground_motion_db.html.
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