现浇楼板对钢筋混凝土框架结构在地震作用下破坏形式的影响
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摘要
"5.12"汶川地震造成一些钢筋混凝土框架结构损坏甚至倒塌。灾后调查发现,框架结构震害特点之一是柱端而非梁端出现塑性铰的"强梁弱柱"破坏形式,这与结构抗震设计概念中的"强柱弱梁"不符。国内外研究表明现浇楼板增大了梁端抗负弯承载力,但其对整个框架结构屈服机制的影响研究依然不足。针对这种现象,应用有限元软件ABAQUS对汶川地震中都江堰市某典型"强梁弱柱"框架进行三维动力弹塑性时程数值模拟,着重从结构角度上分析了现浇楼板对框架结构抗震性能的影响、探讨了负弯矩作用下梁端有效翼缘的取值。经分析,发现按照目前我国规范设计的框架在遭遇大震时较难实现"强柱弱梁"屈服机制。框架设计时宜在柱端弯矩增大系数不变的情况下,负弯矩作用下梁端有效翼缘范围内的板筋参与梁受弯,建议该范围取6倍板宽;大震下框架弹塑性变形验算宜采用考虑现浇楼板的计算模型。
Many reinforced concrete(RC) frame structures were severely damaged or even collapsed during the May 12,2008 great Wenchuan earthquake.Based on survey data collected in Dujiangyan,it was found that plastic hinges appeared at column end,instead of beam end,in many frame structures.This did not coincide with "strong column-weak beam" seismic design criterion.It was believed that one of the main reasons was insufficiently understanding the cast-in-place floor slab effect on frame structures.Applying finite element software ABAQUS,3D elastic-plastic time history simulation of a "strong beam-weak column" RC frame structure in Dujiangyan was analyzed to probe the influence of cast-in-slab on frame seismic performance from structural view.Results showed that RC frame designed according to current codes usually can not achieve "strong column-weak beam" yield mechanism.The numerical results suggested that the rebar in the width of six times of the plate thickness may take part in calculating the bearing capacity of negative moment at the beam end;the model of a frame structure with floor slab is suitable for analyzing the elastic-plastic deflection of frame structures under rare big earthquakes.
Many reinforced concrete(RC) frame structures were severely damaged or even collapsed during the May 12,2008 great Wenchuan earthquake.Based on survey data collected in Dujiangyan,it was found that plastic hinges appeared at column end,instead of beam end,in many frame structures.This did not coincide with "strong column-weak beam" seismic design criterion.It was believed that one of the main reasons was insufficiently understanding the cast-in-place floor slab effect on frame structures.Applying finite element software ABAQUS,3D elastic-plastic time history simulation of a "strong beam-weak column" RC frame structure in Dujiangyan was analyzed to probe the influence of cast-in-slab on frame seismic performance from structural view.Results showed that RC frame designed according to current codes usually can not achieve "strong column-weak beam" yield mechanism.The numerical results suggested that the rebar in the width of six times of the plate thickness may take part in calculating the bearing capacity of negative moment at the beam end;the model of a frame structure with floor slab is suitable for analyzing the elastic-plastic deflection of frame structures under rare big earthquakes.
引文
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[12]马千里,叶列平,陆新征,等.现浇楼板对框架结构柱梁强度比的影响研究[C].汶川地震建筑震害调查与灾后重建分析报告,中国建筑工业出版社,2008:263-271.
[13]杨佑发,梁文广,曹建良.框架结构爆破震动响应的时程预测[J].振动与冲击,2009,28(10):147-149,178.
[14]杨佑发,崔波.框架结构爆破地震的损伤评估[J].振动与冲击,2009,28(10):191-194.
[15]袁勇,禹海涛,陈之毅.软土浅埋框架结构抗震计算方法评价[J].振动与冲击,2009,28(8):50-56.
[16]Yan HX,Yang Q S.Application of damaged plasticity modelin elastic-plastic time-history analysis of RC structures[C].Environmental Vibrations:Prediction,Monitoring,Mitigationand Evaluation(ISEV2009).2009:1433-1439.
[17]阎红霞,杨庆山,张丽英.ABAQUS在超高层结构动力弹塑性分析中的应用[J].震灾防御技术,2010,5(1):108-115.
[18]阎红霞,杨庆山.汶川地震框架柱端弯矩增大系数有效性的研究[J].建筑结构学报,2009,30(SUPPL.2):138-143.
[2]李宏男,肖诗云,霍林生.汶川地震震害调查与启示[J].建筑结构学报,2008,29(4):10-19.
[3]刘国兴,杨庆山,温军.汶川地震都江堰市建筑结构震害详查与分析[J].建筑结构(增刊),2009,39:227-231.
[4]唐九如.钢筋混凝土框架节点抗震研究的新进展[J].工程抗震,1989(4):39-43.
[5]French C W,et al.Effect of floor slab on behavior of s1ab-beam-column connection[C].ACI SP-123,Design of Beam-column Joints for Seismic Resistance,1991.
[6]蒋永生,陈忠范,周绪平,等.整浇梁板的框架节点抗震研究[J].建筑结构学报,1994,15(6):11-16.
[7]郑士举,蒋利学,张伟平,等.现浇混凝土框架梁截面有效翼缘宽度的试验研究与分析[J].结构工程师,2009,25(2):134-140.
[8]French C W,Boroojerdi A.Contribution of RC floor slabs inresisting lateral loads[J].Journal of Structural Engineering,1989,115(1):1-18.
[9]吴勇,雷汲川,杨红,等.板筋参与梁端负弯矩承载力问题的探讨[J].重庆建筑大学学报,2002,24(3):33-37.
[10]管民生,杜宏彪.现浇楼板参与工作后框架结构的pushover分析研究[J].地震工程与工程振动,2005,25(5):117-123.
[11]韦锋,杨红,傅剑平,等.普通钢筋混凝土规则框架的弹塑性地震反应[J].重庆大学学报(自然科学版),2007,30(7):59-65.
[12]马千里,叶列平,陆新征,等.现浇楼板对框架结构柱梁强度比的影响研究[C].汶川地震建筑震害调查与灾后重建分析报告,中国建筑工业出版社,2008:263-271.
[13]杨佑发,梁文广,曹建良.框架结构爆破震动响应的时程预测[J].振动与冲击,2009,28(10):147-149,178.
[14]杨佑发,崔波.框架结构爆破地震的损伤评估[J].振动与冲击,2009,28(10):191-194.
[15]袁勇,禹海涛,陈之毅.软土浅埋框架结构抗震计算方法评价[J].振动与冲击,2009,28(8):50-56.
[16]Yan HX,Yang Q S.Application of damaged plasticity modelin elastic-plastic time-history analysis of RC structures[C].Environmental Vibrations:Prediction,Monitoring,Mitigationand Evaluation(ISEV2009).2009:1433-1439.
[17]阎红霞,杨庆山,张丽英.ABAQUS在超高层结构动力弹塑性分析中的应用[J].震灾防御技术,2010,5(1):108-115.
[18]阎红霞,杨庆山.汶川地震框架柱端弯矩增大系数有效性的研究[J].建筑结构学报,2009,30(SUPPL.2):138-143.
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