高延性混凝土加固框架柱抗震性能试验研究及其轴压比限值分析
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摘要
混凝土框架柱的轴压比较高时,在水平地震荷载作用下通常发生小偏心受压破坏。为改变高轴压比下混凝土柱的破坏形态并提高其抗震性能,提出采用高延性混凝土(HDC)围套加固混凝土柱。设计6个RC柱,其中4个采用HDC或钢筋网高性能复合砂浆加固。通过低周期反复荷载试验,研究加固层形式和轴压比对试件破坏形态、滞回性能、承载力、变形能力、耗能能力和刚度退化的影响。试验结果表明:采用HDC围套加固可使试件的破坏形态由小偏心受压破坏转变为大偏心受压破坏,试件达到极限位移时仍维持稳定的竖向承载力;通过HDC围套加固后,试件的承载力,延性和耗能能力均得到明显提高,刚度退化速率减缓。采用HDC围套加固,可增加柱截面受压区面积,提高柱截面的相对受压区高度,使加固柱的轴压比限值明显提高,同时柱截面仍具有良好的变形能力。
The reinforced concrete(RC) columns are vulnerable to small eccentric compression failures in severe earthquake when the axial load ratio is at a high level. In order to change the failure modes and improve the seismic performance of the RC columns under high axial load ratio,the high ductile concrete(HDC) jacket was proposed to strengthen the RC columns. Six RC columns were designed and four of them were strengthened with HDC jacket or ferrocement jacket. The influence of strengthening schemes and axial load ratios on the failure modes, hysteresis performance, shear capacity, deformation capacity, energy dissipation capacity and stiffness degradation of the specimens were studied by the low cyclic loading test. The experimental results show that the failure mode of the RC columns was changed from small eccentric compression failure to large eccentric compression failure and the vertical load-carrying capacity were stably maintained when the ultimate displacements were reached. The bearing capacity,ductility and energy dissipation capacity of the RC columns were significantly improved and the stiffness degradation rate was slowed down after strengthening with HDC jackets. The area of the compression zone, the relative compression height and the limitation of the axial load ratio of the columns were obviously increased after strengthening. Besides, the column still exhibited good section deformation capacity.
The reinforced concrete(RC) columns are vulnerable to small eccentric compression failures in severe earthquake when the axial load ratio is at a high level. In order to change the failure modes and improve the seismic performance of the RC columns under high axial load ratio,the high ductile concrete(HDC) jacket was proposed to strengthen the RC columns. Six RC columns were designed and four of them were strengthened with HDC jacket or ferrocement jacket. The influence of strengthening schemes and axial load ratios on the failure modes, hysteresis performance, shear capacity, deformation capacity, energy dissipation capacity and stiffness degradation of the specimens were studied by the low cyclic loading test. The experimental results show that the failure mode of the RC columns was changed from small eccentric compression failure to large eccentric compression failure and the vertical load-carrying capacity were stably maintained when the ultimate displacements were reached. The bearing capacity,ductility and energy dissipation capacity of the RC columns were significantly improved and the stiffness degradation rate was slowed down after strengthening with HDC jackets. The area of the compression zone, the relative compression height and the limitation of the axial load ratio of the columns were obviously increased after strengthening. Besides, the column still exhibited good section deformation capacity.
引文
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[14]邓明科,潘姣姣,秦萌,等.高延性混凝土单轴受压本构模型研究[J].西安建筑科技大学学报:自然科学版,2016,48(6):826-831(Deng Mingke,Pan Jiaojiao,Qin Meng,et al.Research on the constitutive relation of high ductile fiber reinforced concrete under uniaxial compression[J].Journal of Xi’an University of Architecture&Technology:Natural Science Edition,2016,48(6):826-831(in Chinese))
[2]郭子雄,张杰,李传林.预应力钢板箍加固高轴压比框架柱抗震性能研究[J].土木工程学报,2009,42(12):112-117(Guo Zixiong,Zhang Jie,Li Chuanlin.Seismic strengthening of rectangular RC columns using prestressing steel jacket[J].Journal of Civil Engineering,2009,42(12):112-117(in Chinese))
[3]周长东,田腾,吕西林,等.预应力碳纤维条带加固高轴压比混凝土圆柱抗震性能试验研究[J].建筑结构学报,2012,33(11):115-123(Zhou Changdong,Tian Teng,Lu Xilin,et al.Experimental study on seismic behavior of circular RC columns strengthened with pre-stressed CFRP belts under high axial compression[J].Journal of Building Structures,2012,33(11):115-123(in Chinese))
[4]顾冬生,吴刚,吴智深,等.CFRP加固高轴压比钢筋混凝土短圆柱抗震性能试验研究[J].工程抗震与加固改造,2006,28(6):71-77(Gu Dongsheng,Wu Gang,Wu Zhisheng,et al.Experimental study on seismic performance of RC short circular columns strengthened with CFRP composites under high-level compression[J].Earthquake Resistance Engineering and Retrofitting,2006,28(6):71-77(in Chinese))
[5]Wang Daiyu,Huang Le,Yu Tao,et al.Seismic performance of CFRP-retrofitted large-scale square RCcolumns with high axial compression ratios[J].Composites for Construction,2017,21(5):04017031-1-04017031-12
[6]Li V C,Wang S X,Wu C.Tensile strain-hardening behavior of PVA-ECC[J].ACI Materials Journal,2001,98-M52:483-492
[7]Li V C.On engineered cementitious composites(ECC)a review of the material and its applications[J].Journal of Advanced Concrete Technology,2003,1(3):215-230
[8]Li V C,Leung C K Y.Steady-state and multiple cracking of short random fiber composites[J].Journal of Engineering Mechanics,1992,188(11):2246-2264
[9]寇佳亮,邓明科,梁兴文.延性纤维增强混凝土单轴拉伸性能试验研究[J].建筑结构,2013,43(1):59-64(Kou Jialiang,Deng Mingke,Liang Xingwen.Experimental study of uniaxial tensile properties of ductile fiber reinforced concrete[J].Building Structure,2013,43(1):59-64(in Chinese))
[10]邓明科,刘海勃,秦萌,等.高延性纤维混凝土抗压韧性试验研究[J].西安建筑科技大学学报:自然科学版,2015,47(5):660-667(Deng Mingke,Liu Haibo,Qin Meng,et al.Experimental research on compressive toughness of the high ductile fiber reinforced concrete[J].Journal of Xi’an University of Architecture&Technology:Natural Science Edition,2015,47(5):660-667(in Chinese))
[11]邓明科,张辉,梁兴文,等.高延性纤维混凝土短柱抗震性能试验研究[J].建筑结构学报,2015,36(12):62-69(Deng Mingke,Zhang Hui,Liang Xingwen,et al.Experimental study on seismic behavior of high ductile fiber reinforced concrete short column[J].Journal of Building Structures,2015,36(12):62-69(in Chinese))
[12]邓明科,卢化松,杨开屏,等.型钢高延性混凝土短梁抗剪性能试验研究[J].建筑结构学报,2015,36(10):73-80(Deng Mingke,Lu Huasong,Yang Kaiping,et al.Experimental study on shear behavior of steel reinforced high ductile concrete short beams[J].Journal of Building Structures,2015,36(10):73-80(in Chinese))
[13]肖建庄,朱伯龙.钢筋混凝土框架柱轴压比限值试验研究[J].建筑结构学报,1998,19(5):2-7(Xiao Jianzhuang,Zhu Bolong.Experimental research on limit value of axial compression ratio for reinforced concrete frame columns[J].Journal of Building Structures,1998,19(5):2-7(in Chinese))
[14]邓明科,潘姣姣,秦萌,等.高延性混凝土单轴受压本构模型研究[J].西安建筑科技大学学报:自然科学版,2016,48(6):826-831(Deng Mingke,Pan Jiaojiao,Qin Meng,et al.Research on the constitutive relation of high ductile fiber reinforced concrete under uniaxial compression[J].Journal of Xi’an University of Architecture&Technology:Natural Science Edition,2016,48(6):826-831(in Chinese))