外包钢加固火灾后钢筋混凝土柱的试验研究
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摘要
通过3根外包角钢加固的ISO834标准火灾作用后钢筋混凝土柱的受力性能试验以及3根未加固的ISO834标准火灾作用后钢筋混凝土柱和3根常温下钢筋混凝土柱的对比试验,研究了火灾后钢筋混凝土柱的性能以及外包钢加固火灾后钢筋混凝土柱的有效性。试验结果表明:火灾后试件的刚度退化显著,在该文的试验参数和升温条件下,从开始加载到80%极限荷载的不同加载阶段,轴压柱的轴向刚度只有常温下轴向刚度的0.22~0.37,偏压柱的弯曲刚度只有常温下弯曲刚度的0.13~0.18;外包角钢加固对火灾后试件的刚度修复有一定的效果,不同荷载水平下,加固后轴压试件的轴向刚度与常温下试件刚度的比值在0.41~0.89之间,偏压试件的弯曲刚度与常温下试件刚度的比值在0.33~0.91之间。火灾后试件承载能力退化严重,在该文的试验参数和升温条件下,火灾后试件的承载力水平只有常温下的0.25~0.37;利用外包角钢对火灾后的试件进行加固,能将试件的承载力提高至试件未受火时大致相当的水平,加固后试件的承载力与未受火试件承载力的比值在0.97~1.06之间,外包钢加固对火灾后试件承载能力的修复效果十分显著。
By the tests on three reinforced concrete columns strengthened with external steel clad after exposure to ISO834 standard fire and three reinforced concrete columns without strengthening after exposure to ISO834 standard fire as well as three reinforced concrete columns without exposure to fire,the mechanical properties of reinforced concrete columns after exposure to ISO834 standard fire as well as the strengthening effectiveness of external steel clad are experimentally studied.Test results shows that after exposed to fire,the rigidity and load bearing capacity of specimens are all declined sharply compared with that at normal temperature without exposure to fire.In various loading stages from the initial loading to 80% ultimate strength,the ratio of axial rigidity of concentric columns after exposure to fire and at normal temperature was ranged from 0.22 to 0.37,the ratio of flexural rigidity of eccentric columns after exposure to fire and at normal temperature was ranged from 0.14 to 0.18,and the ratio of the load bearing capacity of specimens after exposure to fire and at normal temperature was ranged from 0.25 to 0.37.But the rigidity and load bearing capacity can be increased to a certain extent when strengthened with external steel clad.The ratio of axial rigidity of concentric columns strengthened with external steel clad and at normal temperature was ranged from 0.41 to 0.89,the ratio of flexural rigidity of eccentric columns strengthened with external steel clad and at normal temperature was ranged from 0.33 to 0.91,and the ratio of the load bearing capacity of specimens strengthened with external steel clad and at normal temperature was ranged from 0.97 to 1.06.The strengthening effect of external steel clad on load bearing capacity of reinforced concrete columns after exposure to fire is remarkable.
By the tests on three reinforced concrete columns strengthened with external steel clad after exposure to ISO834 standard fire and three reinforced concrete columns without strengthening after exposure to ISO834 standard fire as well as three reinforced concrete columns without exposure to fire,the mechanical properties of reinforced concrete columns after exposure to ISO834 standard fire as well as the strengthening effectiveness of external steel clad are experimentally studied.Test results shows that after exposed to fire,the rigidity and load bearing capacity of specimens are all declined sharply compared with that at normal temperature without exposure to fire.In various loading stages from the initial loading to 80% ultimate strength,the ratio of axial rigidity of concentric columns after exposure to fire and at normal temperature was ranged from 0.22 to 0.37,the ratio of flexural rigidity of eccentric columns after exposure to fire and at normal temperature was ranged from 0.14 to 0.18,and the ratio of the load bearing capacity of specimens after exposure to fire and at normal temperature was ranged from 0.25 to 0.37.But the rigidity and load bearing capacity can be increased to a certain extent when strengthened with external steel clad.The ratio of axial rigidity of concentric columns strengthened with external steel clad and at normal temperature was ranged from 0.41 to 0.89,the ratio of flexural rigidity of eccentric columns strengthened with external steel clad and at normal temperature was ranged from 0.33 to 0.91,and the ratio of the load bearing capacity of specimens strengthened with external steel clad and at normal temperature was ranged from 0.97 to 1.06.The strengthening effect of external steel clad on load bearing capacity of reinforced concrete columns after exposure to fire is remarkable.
引文
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[3]卢亦焱,陈少雄,赵国藩.外包钢与碳纤维布复合加固钢筋混凝土柱抗震性能试验研究[J].土木工程学报,2005,38(8):10―17.Lu Yiyan,Chen Shaoxiong,Zhao Guofan.Anexperimental study on the seismic behavior of reinforcedconcrete column strengthened with bonded steel hoopsand carbon fiber reinforced polymer sheet[J].ChinaCivil Engineer Journal,2005,38(8):10―17.(inChinese)
[4]陆洲导,刘长青,张克纯,王焕杰.外包钢套法加固钢筋混凝土框架节点试验研究[J].四川大学学报(工程科学版),2010,42(3):56―62.Lu Zhoudao,Liu Changqing,Zhang Kechun,WangHuanjie.Experimental study on the seismic performanceof enveloped steel strengthened RC frame joint[J].Journal of Sichuan University(Engineering ScienceEdition),2010,42(3):56―62.(in Chinese)
[5]陈金锋,江世永.外包钢加固混凝土时外包钢利用系数的确定[J].四川建筑科学研究,2004,30(1):63―65.Chen Jinfeng,Jiang Shiyong.The defining of outsidesteel utilization coefficient in concrete strengthened bywrapping steel outside[J].Sichuan Building Science,2004,30(1):63―65.(in Chinese)
[6]潘志宏,李爱群.基于纤维模型的外粘型钢加固混凝土柱静力弹塑性分析[J].东南大学学报(自然科学版),2009,39(3):552―556.Pan Zhihong,Li Aiqun.Nonlinear static analysis on RCcolumn strengthened with externally bonded steel framebased on fiber model[J].Journal of Southeast University(Natural Science Edition),2009,39(3):552―556.(inChinese)
[7]Chai Y H,Priestley M J N,Seible F.Analytical mode forsteel jacketed RC circular bridge columns[J].Journal ofStructural Engineering,1994,120(8):2358―2376.
[8]Yan Xiao,Wu Hui.Retrofit of reinforced concretecolumns using partially stiffened steel jackets[J].Journalof Structural Engineering,2003,129(6):725―732.
[9]中华人民共和国国家标准.GB50367-2006混凝土结构加固设计规范[S].北京:中国建筑工业出版社,2006.Standard of P.R.China.GB 50367-2006 Design code forstrengthening concrete structure[S].Beijing:ChinaArchitecture&Building Press,2006.(in Chinese)
[10]刘利先,时旭东,过镇海.增大截面法加固高温损伤混凝土柱的试验研究[J].工程力学,2003,20(5):18―23.Liu Lixian,Shi Xudong,Guo Zhenhai.Experimentalinvestigation of strengthened reinforced concretecolumns after exposure to high temperature[J].Engineering Mechanics,2003,20(5):18―23.(inChinese)
[11]王李果,陆洲导,绳钦柱.采用碳纤维布加固火灾后预应力混凝土框架的试验研究[J].火灾科学,2003,12(4):218―223.Wang Liguo,Lu Zhoudao,Sheng Qinzhu.Experimentalresearch on pre-stressed concrete frame after hightemperature rehabilitated by CFRP[J].Fire SafetyScience,2003,12(4):218―223.(in Chinese)
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