UHTCC/RC复合梁剪切性能试验研究
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摘要
超高韧性水泥基复合材料(UHTCC)以其多重细密稳态开裂模式在宏观上展现出拉应变硬化特征,具有优异的裂缝控制能力,可用作修补材料。采用UHTCC替代部分受拉区混凝土对有腹筋UHTCC/RC复合梁进行了剪切性能研究。试验变量为UHTCC层厚度。结果表明:不同UHTCC层厚度的UHTCC/RC复合梁,其抗剪承载力均明显高于RC对比梁;即便配置较密集的箍筋,仍然无法阻止界面剥离,但可以避免界面剥离产生的荷载抖降;UHTCC能够限制和分散上层混凝土中的裂缝。最后,给出了UHTCC/RC复合梁在实际应用中的建议。
Ultra high toughness cementitious composites( UHTCC) macroscopically presents tensile strain hardening characteristic because of its multiple fine steady cracking,which has excellent crack control capacity,and is suitable to be used as repair materials. The shear behavior of UHTCC/RC composite beams with web reinforcement is investigated by using UHTCC replacing partial concrete in tension region. The test variable is the thickness of UHTCC layer. The test results show that the shear bearing capacity of UHTCC/RC composite beams with different thickness of UHTCC layer is obviously higher than that of RC beam. And although the use of stirrups is still impossible to completely prevent the interface from debonding,and load drops caused by interface debonding can be effectively avoided. It is also observed that UHTCC can restrict and disperse the cracks in upper concrete. Finally,some suggestions on the practical application of UHTCC/RC composite beams are provided.
Ultra high toughness cementitious composites( UHTCC) macroscopically presents tensile strain hardening characteristic because of its multiple fine steady cracking,which has excellent crack control capacity,and is suitable to be used as repair materials. The shear behavior of UHTCC/RC composite beams with web reinforcement is investigated by using UHTCC replacing partial concrete in tension region. The test variable is the thickness of UHTCC layer. The test results show that the shear bearing capacity of UHTCC/RC composite beams with different thickness of UHTCC layer is obviously higher than that of RC beam. And although the use of stirrups is still impossible to completely prevent the interface from debonding,and load drops caused by interface debonding can be effectively avoided. It is also observed that UHTCC can restrict and disperse the cracks in upper concrete. Finally,some suggestions on the practical application of UHTCC/RC composite beams are provided.
引文
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[2]建功.旧混凝土防渗渠道破坏的原因及修补改建措施[J].水利与建筑工程学报,2001,7(2):1-7.
[3]赵承明.混凝土结构损伤劣化机理及加固维护技术研究[J].水利与建筑工程学报,2014,12(4):103-106.
[4]徐世火良,李贺东.超高韧性水泥基复合材料研究进展及其工程应用[J].土木工程学报,2008,41(6):45-60.
[5]Leung C K Y,Li V C.Strength-based and fracture-based approaches in the analysis of fibre debonding[J].Journal of Materials Science Letters,1990,9(10):1140-1142.
[6]Li V C,Mishra D K,Wu H C.Matrix design for pseudostrain-hardening fibre reinforced cementitious composites[J].Materials and Structures,1995,28(10):586-595.
[7]郭平功,田砾,李晓东,等.PVA-ECC在工程维修中的应用[J].国外建材科技,2006,27(4):82-84.
[8]丁一,陈小兵,李荣.ECC材料的研究进展与应用[J].建筑结构,2007,37(S1):378-382.
[9]Maalej M,Li V C.Introduction of strain hardening engineered cementitious composites in design of reinforced concrete flexural members for improved durability[J].Aci Structural Journal,1995,92(2):167-176.
[10]Wang N,Xu S L.Flexural response of reinforced concrete beams strengthened with post-poured ultra high toughness cementitious composites layer[J].Journal of Central South University of Technology,2011,18(3):932-939.
[11]徐世火良,王楠,尹世平.超高韧性水泥基复合材料加固钢筋混凝土梁弯曲控裂试验研究[J].建筑结构学报,2011,32(9):115-122.
[12]徐世火良,王楠,李庆华.超高韧性水泥基复合材料增强普通混凝土复合梁弯曲性能试验研究[J].土木工程学报,2010,41(5):17-22.
[13]侯利军,陈达,孙晋永,等.RC/UHTCC复合梁的弯曲与界面性能试验研究[J].水利学报,2014,45(S1):100-107.
[14]Hou L J,Xu S L,Liu H,et al.Flexural and interface behaviors of reinforced concrete/ultra-high toughness cementitious composite(RC/UHTCC)beams J[J].Journal of Advanced Concrete Technology,2015,13(2):82-93.
[15]Kim J H J,Yun M L,Won J P,et al.Shear capacity and failure behavior of DFRCC repaired RC beams at tensile region[J].Engineering Structures,2007,29(1):121-131.
[16]Zhang Y,Bai S,Zhang Q B,et al.Failure behavior of strain hardening cementitious composites for shear strengthening RC member[J].Construction&Building Materials,2015,78:470-473.
[17]中华人民共和国住房和城乡建设部.混凝土结构设计规范:GB50010—2010[S].北京:中国建筑工业出版社,2010.