L形FRP粘贴法加固混凝土框架梁负弯矩区试验研究
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摘要
提出了一种混凝土框架梁负弯矩区受弯性能加固的L形FRP片材粘贴加固法,该方法利用角钢实现FRP在梁柱阴角处的转向锚固.通过6个足尺框架梁柱边节点试件的单向静力加载和低周反复加载试验,对比了利用L形FRP粘贴加固法和规范建议FRP粘贴加固法加固后梁的破坏形态、受弯承载力、刚度、延性、耗能能力等性能指标.试验结果表明,粘贴L形FRP片材加固后,梁根部FRP与试件相应位置截面在加载过程中变形协调,应变关系基本符合平截面假定.低周反复荷载作用下,梁受弯承载力和刚度的提高幅度与静力荷载作用下几乎相同,表明L形FRP粘贴加固法中的锚固装置完全限制了阴角处FRP片材从被加固体基面上法向剥离的位移趋势,使得加固效果更加稳定.
The L-shaped fiber reinforced polymer(FRP) bonding method for enhancing the flexural performance of negative moment region of RC beams is proposed,in which angle steel is settled to anchor FRP sheet at the frame joint.Six full scale frame joint specimens were tested under static load or lowfrequency cyclic load.Then,the failure mode,flexural capacity,stiffness,ductility and energy dissipation ability were compared between the RC beams strengthened by the proposed L-shaped FRP bonding method and those strengthened by the recommended method in current specification.The experimental results showthat by the L-shaped FRP bonding method,deformation coordination between the FRP at the beam root and the corresponding section of the frame beam are achieved in the process of loading,and thus the stress-strain relationship basically agrees with the plane crosssection assumption.Under lowfrequency cyclic load,the increase of flexural capacity and stiffness of the beam are almost the same as those under the action of static loads.The trend of FRP debonding vertically from the surface of concrete can be completely restricted by the anchor device and thus more stable strengthening effect is achieved.
The L-shaped fiber reinforced polymer(FRP) bonding method for enhancing the flexural performance of negative moment region of RC beams is proposed,in which angle steel is settled to anchor FRP sheet at the frame joint.Six full scale frame joint specimens were tested under static load or lowfrequency cyclic load.Then,the failure mode,flexural capacity,stiffness,ductility and energy dissipation ability were compared between the RC beams strengthened by the proposed L-shaped FRP bonding method and those strengthened by the recommended method in current specification.The experimental results showthat by the L-shaped FRP bonding method,deformation coordination between the FRP at the beam root and the corresponding section of the frame beam are achieved in the process of loading,and thus the stress-strain relationship basically agrees with the plane crosssection assumption.Under lowfrequency cyclic load,the increase of flexural capacity and stiffness of the beam are almost the same as those under the action of static loads.The trend of FRP debonding vertically from the surface of concrete can be completely restricted by the anchor device and thus more stable strengthening effect is achieved.
引文
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[11]Teng J G,Chen G M,Chen J F.Effect of load distri-bution on IC debonding in FRP-plated RC beams[C]//Proceedings of the 5th International Conferenceon FRP Composites in Civil Engineering.Beijing,China,2010:485-489.
[12]施嘉伟,朱虹,吴智深.BFRP/HFRP布-混凝土界面黏结性能试验研究[J].东南大学学报:自然科学版,2010,40(3):554-558.Shi Jiawei,Zhu Hong,Wu Zhishen.Experimentalstudy on bond behavior between basalt/hybrid FRPsheet and concrete substrates[J].Journal of SoutheastUniversity:Natural Science Edition,2010,40(3):554-558.(in Chinese)
[13]Dalfre G M,Barros J A.Flexural strengthening of RCcontinuous slab strips using NSM CFRP laminates[J].Advances in Structural Engineering,2011,14(6):1223-1245.
[14]中华人民共和国国家标准.GB50608—2010纤维增强复合材料建设工程应用技术规范[S].北京:中国建筑工业出版社,2010.
[2]王亚勇.汶川地震建筑震害启示——抗震概念设计[J].建筑结构学报,2008,29(4):20-25.Wang Yayong.Lessons learnt from building damages inthe Wenchuan earthquake—seismic concept design ofbuildings[J].Journal of Building Structures,2008,29(4):20-25.(in Chinese)
[3]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.
[4]Farahbod F,Mostofinejad D.Experimental study ofmoment redistribution in RC frames strengthened withCFRP sheets[J].Composite Structures,2011,93(9):1168-1177.
[5]石铭,屈文俊.粘贴碳纤维布对框架梁端负弯矩区加固的试验探索[J].结构工程师,2006,22(2):73-75,41.Shi Ming,Qu Wenjun.Exploring study on the negativemoment of the frame beam strengthened by CFRP[J].Structural Engineers,2006,22(2):73-75,41.(inChinese)
[6]侯发亮.建筑结构粘结加固的理论与实践[M].武汉:武汉大学出版社,2003.
[7]洪一红.CFRP侧面加固钢筋混凝土梁负弯矩区抗弯性能试验研究[D].杭州:浙江大学建筑工程学院,2007.
[8]Lu X Z,Jiang J J,Teng J G,et al.Finite element sim-ulation of debonding in FRP-to-concrete bonded joints[J].Construction and Building Materials,2006,20(6):412-424.
[9]Niu H D,Wu Z S.Effects of FRP-concrete interfacebond properties on the performance of RIC beamsstrengthened in flexure with externally bonded FRPsheets[J].Journal of Materials in Civil Engineering,2004,18(5):723-731.
[10]Shi J W,Zhu H,Wu Z S,et al.Bond behavior be-tween basalt fiber-reinforced polymer sheet and con-crete substrate under the coupled effects of freeze-thawcycling and sustained load[J].Journal of Compositesfor Construction,2013,17(4):530-542.
[11]Teng J G,Chen G M,Chen J F.Effect of load distri-bution on IC debonding in FRP-plated RC beams[C]//Proceedings of the 5th International Conferenceon FRP Composites in Civil Engineering.Beijing,China,2010:485-489.
[12]施嘉伟,朱虹,吴智深.BFRP/HFRP布-混凝土界面黏结性能试验研究[J].东南大学学报:自然科学版,2010,40(3):554-558.Shi Jiawei,Zhu Hong,Wu Zhishen.Experimentalstudy on bond behavior between basalt/hybrid FRPsheet and concrete substrates[J].Journal of SoutheastUniversity:Natural Science Edition,2010,40(3):554-558.(in Chinese)
[13]Dalfre G M,Barros J A.Flexural strengthening of RCcontinuous slab strips using NSM CFRP laminates[J].Advances in Structural Engineering,2011,14(6):1223-1245.
[14]中华人民共和国国家标准.GB50608—2010纤维增强复合材料建设工程应用技术规范[S].北京:中国建筑工业出版社,2010.
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