地震作用下无筋砌体墙的抗剪可靠度分析
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摘要
无筋砌体墙主要用来承受重力荷载,同时当受到风荷载和地震作用时又需要承受横向荷载。横向荷载和竖向荷载同时作用使砌体墙处于受拉、受压和受剪状态,砌体受拉和受剪破坏会导致砌体垮塌、人员伤亡以及经济损失。目前关于无筋砌体墙受压或受弯性能已有大量的研究,但对于无筋砌体墙在受竖向荷载和横向荷载同时作用时抗剪能力研究甚少。本文采用概率模型来分析无筋砌体墙在地震作用下的抗剪承载力可靠度。无筋砌体墙受剪极限状态是基于已有的试验结果和有关文献评论来定义的,抗剪切能力考虑了砌体墙在受压和受剪下的不确定因素以及活荷载/雪荷载与恒荷载的比率和砌体墙高宽比。利用蒙特卡罗方法来进行砌体墙可靠度的分析,其中还考虑到计算模型的影响。最后,影响无筋砌体墙在地震作用下抗剪能力各因素的敏感度分析,分析结果为确定其是影响抗剪性能的主要因素还是次要因素提供了理论依据。
Unreinforced masonry shear walls are mainly used to support gravity loads.In the meantime,the walls may need to carry the lateral loads when subjected to winds and earthquakes.The lateral and gravity loads result in tension and shear combined with compression in the masonry wall.The shear or tension failure of the shear wall may lead to the collapse of the building and result in casualties and economic losses.Although the reliability of unreinforced masonry shear walls under compression and/or bending moment has been studied,very little work has been done to investigate the reliability of unreinforced masonry wall under combined gravity and lateral loads.This paper presents a probabilistic model to determine the structural reliability of typical unreinforced masonry walls under combined gravity and lateral loads.A performance limit state is defined for the walls under the combined loads,based on experimental test results and literature review.Shear capacity is established incorporating the uncertainty in compression and shear strength of masonry,ratio of snow/live load to dead load,and ratio of wall height to thickness.Monte Carlo Simulation is used to perform the reliability analysis.Model error is considered in the analysis.Lastly,a sensitivity analysis is performed to identify the key contributors to the reliability of the unreinforced masonry wall under the lateral loads.The results provide a base to evaluate whether consistent safety is achieved for unreinforced masonry walls that are subjected to different load combinations.
Unreinforced masonry shear walls are mainly used to support gravity loads.In the meantime,the walls may need to carry the lateral loads when subjected to winds and earthquakes.The lateral and gravity loads result in tension and shear combined with compression in the masonry wall.The shear or tension failure of the shear wall may lead to the collapse of the building and result in casualties and economic losses.Although the reliability of unreinforced masonry shear walls under compression and/or bending moment has been studied,very little work has been done to investigate the reliability of unreinforced masonry wall under combined gravity and lateral loads.This paper presents a probabilistic model to determine the structural reliability of typical unreinforced masonry walls under combined gravity and lateral loads.A performance limit state is defined for the walls under the combined loads,based on experimental test results and literature review.Shear capacity is established incorporating the uncertainty in compression and shear strength of masonry,ratio of snow/live load to dead load,and ratio of wall height to thickness.Monte Carlo Simulation is used to perform the reliability analysis.Model error is considered in the analysis.Lastly,a sensitivity analysis is performed to identify the key contributors to the reliability of the unreinforced masonry wall under the lateral loads.The results provide a base to evaluate whether consistent safety is achieved for unreinforced masonry walls that are subjected to different load combinations.
引文
[1]清华大学土木工程结构专家组,西南交通大学土木工程结构专家组,北京交通大学土木工程结构专家组.汶川地震建筑震害分析[J].建筑结构学报,2008,29(4):1-9(Civil and structural groups of Tsinghua University,Civil and structural groups of Xin’an Jiaotong University,Civil and structural groups of Beijing Jiaotong University.Analysis on seismic damage of buildings in Wenchuanearthquake[J].Journal of Building Structures,2008,29(4):1-9(in Chinese))
[2]GB 50003—2001砌体结构设计规范[S].北京:中国建筑工业出版社,2001(GB 50003—2001 Code for designof masonry structure[S].Beijing:China Architecture&Building Press,2003(in Chinese))
[3]吕伟荣,施楚贤,刘桂秋.剪压复合作用下砌体的静力与抗震抗剪强度[J].工程力学,2008,25(4):158-164(Lu Weirong,Shi Chuxian,Liu Guiqiu.Static and seismicshear strength of masonry under shear-compression loading[J].Engineering Mechanics,2008,25(4):158-164(inChinese))
[4]Krit C H,Mario M A.Modeling of unreinforced masonrywalls under shear and compression[J].Engineering Structures,2007,29(9):2056-2068
[5]施楚贤.无筋砌体构件承载力计算[J].建筑结构,2003,33(4):64-66(Shi Chuxian.Shear capacity of unreinforcedMasonry Members[J].Journal of Building Structures,2003,33(4):64-66(in Chinese))
[6]Stewart M G,Lawrence S J.Model error,structure reliabilityand partial safety factors for structural masonry in compression[J].MasonryInternational,2007,20(3):107-16
[7]Ellingwood B.Analysis of reliability of masonry structures[J].Journal of the Structural Division,1981,107(5):757-773
[8]Ellingwood B,Tallin A.Limit states criteria for masonryconstruction[J].Journal of Structural Engineering,1985,111(1):108-122
[9]GB 50068—2001建筑结构可靠度设计统一标准[S].北京:中国建筑工业出版社,2001(GB 50068—2001Unified standard for reliability design of building structures[S].Beijing:China Architecture&Building Press,2001(in Chinese))
[10]Ellingwood B.LRFD:implementing structural reliability inprofessional practic[eJ].Engineering Structures,2000,22(2):106-115
[11]刘桂秋.砌体结构的基本性能分析[D].长沙:湖南大学,2005
[12]GB50011—2001建筑抗震设计规范[S].北京:中国建筑工业出版社,2001(GB 50011—2001 Code for seismicdesign of buildings[S].Beijing:China Architecture&Building Press,2001(in Chinese))
[13]Zhai X M,Stewart M G.Structural reliability analysis ofreinforced grouted concrete block masonry walls incompression[R].New South Wales:The University ofNew Castle,2008
[2]GB 50003—2001砌体结构设计规范[S].北京:中国建筑工业出版社,2001(GB 50003—2001 Code for designof masonry structure[S].Beijing:China Architecture&Building Press,2003(in Chinese))
[3]吕伟荣,施楚贤,刘桂秋.剪压复合作用下砌体的静力与抗震抗剪强度[J].工程力学,2008,25(4):158-164(Lu Weirong,Shi Chuxian,Liu Guiqiu.Static and seismicshear strength of masonry under shear-compression loading[J].Engineering Mechanics,2008,25(4):158-164(inChinese))
[4]Krit C H,Mario M A.Modeling of unreinforced masonrywalls under shear and compression[J].Engineering Structures,2007,29(9):2056-2068
[5]施楚贤.无筋砌体构件承载力计算[J].建筑结构,2003,33(4):64-66(Shi Chuxian.Shear capacity of unreinforcedMasonry Members[J].Journal of Building Structures,2003,33(4):64-66(in Chinese))
[6]Stewart M G,Lawrence S J.Model error,structure reliabilityand partial safety factors for structural masonry in compression[J].MasonryInternational,2007,20(3):107-16
[7]Ellingwood B.Analysis of reliability of masonry structures[J].Journal of the Structural Division,1981,107(5):757-773
[8]Ellingwood B,Tallin A.Limit states criteria for masonryconstruction[J].Journal of Structural Engineering,1985,111(1):108-122
[9]GB 50068—2001建筑结构可靠度设计统一标准[S].北京:中国建筑工业出版社,2001(GB 50068—2001Unified standard for reliability design of building structures[S].Beijing:China Architecture&Building Press,2001(in Chinese))
[10]Ellingwood B.LRFD:implementing structural reliability inprofessional practic[eJ].Engineering Structures,2000,22(2):106-115
[11]刘桂秋.砌体结构的基本性能分析[D].长沙:湖南大学,2005
[12]GB50011—2001建筑抗震设计规范[S].北京:中国建筑工业出版社,2001(GB 50011—2001 Code for seismicdesign of buildings[S].Beijing:China Architecture&Building Press,2001(in Chinese))
[13]Zhai X M,Stewart M G.Structural reliability analysis ofreinforced grouted concrete block masonry walls incompression[R].New South Wales:The University ofNew Castle,2008
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