带U型箍的FRP板-混凝土搭接接头单剪试验研究
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摘要
大量既有基础设施由于材料性能退化、超负荷使用等原因性能退化,不能满足使用需求,因此需要进行加固、修复和改造。纤维增强复合材料(Fiber Reinforced Polymer/Plastic,简称FRP)是一种新型高性能材料,具有高强、轻质、耐腐及施工便捷等优越的性能,已广泛应用于工程结构的加固。将FRP板粘贴于钢筋混凝土梁/板等受弯构件,提升其抗弯承载能力,是钢筋混凝土结构主流的受弯加固技术之一。FRP加固钢筋混凝土梁/板的极限承载能力通常由中部剥离破坏或混凝土保护层剥离破坏控制,剥离破坏发生时FRP的最大应变仅为其极限抗拉应变的20%～40%,未能有效地利用FRP抗拉强度。FRP-混凝土搭接接头单剪试验常用于研究FRP-混凝土的粘结性能,采用该类试验研究带U型箍的FRP-混凝土的粘结性能,研究U型锚对粘结性能的提升,从而有助于提升配置U型箍的FRP加固钢筋混凝土受弯构件的力学行为。试验包含了6个试件,重点研究U型箍角度的影响。试验结果表明:锐角(如35°和45°)能够显著地提升FRP-混凝土界面粘结性能。
A large number of existing infrastructure suffer from structural deficiency due to degradation of constituent material properties as well as overloading,therefore need to be upgraded or retrofitted. Fiber Reinforced Polymer(FRP) composites are widely used for the strengthening of concrete structures due to their superior properties such as high strength-to-weight ratio,excellent corrosion resistance. Among these applications of FRPs for strengthening RC structures,externally bonding of an FRP plate to the soffit of RC beams is one of major applications to upgrade the flexural strength of the member. The ultimate bearing capacity of FRP-reinforced reinforced concrete beams/boards is usually controlled by the central peeling failure or the peeling failure of the concrete protective layer. The maximum strain of FRP is only 20%～40%of the ultimate tensile strain when the peeling failure occurs. FRP tensile strength was not effectively utilized. FRP-to-concrete bonded joints have been commonly used to investigate the bond behavior of the FRP-to-concrete interface. This kind of test is used to study the bonding performance of FRP-concrete with U-shaped hoop,and the improvement of the bonding performance of U-shaped anchor is studied,which helps to improve the mechanical behavior of FRP-reinforced reinforced concrete flexural members with U-shaped hoop. The test consisted of six test pieces,focusing on the effect of the U-Hoop angle. The test results show that acute angles(such as 35°and 45°) can significantly improve the bonding properties of FRP-concrete interface.
A large number of existing infrastructure suffer from structural deficiency due to degradation of constituent material properties as well as overloading,therefore need to be upgraded or retrofitted. Fiber Reinforced Polymer(FRP) composites are widely used for the strengthening of concrete structures due to their superior properties such as high strength-to-weight ratio,excellent corrosion resistance. Among these applications of FRPs for strengthening RC structures,externally bonding of an FRP plate to the soffit of RC beams is one of major applications to upgrade the flexural strength of the member. The ultimate bearing capacity of FRP-reinforced reinforced concrete beams/boards is usually controlled by the central peeling failure or the peeling failure of the concrete protective layer. The maximum strain of FRP is only 20%～40%of the ultimate tensile strain when the peeling failure occurs. FRP tensile strength was not effectively utilized. FRP-to-concrete bonded joints have been commonly used to investigate the bond behavior of the FRP-to-concrete interface. This kind of test is used to study the bonding performance of FRP-concrete with U-shaped hoop,and the improvement of the bonding performance of U-shaped anchor is studied,which helps to improve the mechanical behavior of FRP-reinforced reinforced concrete flexural members with U-shaped hoop. The test consisted of six test pieces,focusing on the effect of the U-Hoop angle. The test results show that acute angles(such as 35°and 45°) can significantly improve the bonding properties of FRP-concrete interface.
引文
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[11]J.G. Teng,S.T. Smith,J. Yao,et al. Intermediate Crackinduced Debonding in RC Beams and Slabs[J]. Construction and Building Materials,2003,17(6-7):447-462.
[12]纪铭.纤维增强材料补强混凝土结构技术应用研究[J].科技创新月刊,2016,29(2):119-121.
[13]Sharif A,Al-Sulaimani GJ,Basunbul IA,et al. Strengthening of Initially Loaded Reinforced Concrete Beams Using FRP plates[J]. Structural Journa,1994,91(2):160-168.
[14]Yun YC,Wu YF,Tang WC. Performance of FRP Bonding Systems under Fatigue Loading[J]. Engineering Structures,2008,30(11):3129-3140.
[15]Smith ST. FRP Anchors:Recent Advances in Research and Understanding. In:Proceedings,Second Asia-Pacific Conference on FRP in Structures. APFIS,2009:35-44.
[16]Smith S T,Teng J G. Shear-Bending Interaction in Debonding Failures of FRP-Plated RC Beams[J]. Advances in Structural Engineering,2003,6(3):183-199.
[2] Smith ST,Teng JG. FRP-strengthened RC Beams-I:Review of Debonding Strength Models[J]. Engineering Structures,2002,24(4):385-395.
[3] Smith ST,Teng JG. FRP-strengthened RC Beams-Ⅱ:Assessment of Debonding Strength Models[J]. Engineering Structures,2002,24(4):397-417.
[4]Smith ST,Teng JG. Shear-bending Interaction in Debonding Failures of FRP-plated RC Beams[J]. Advances in Structural Engineering,2003,6(3):183-99.
[5]卢亦焱,李晓瑾,张号军,等.集中荷载下井字形CFRP与钢板条带复合加固RC双向板试验研究[J].应用基础与工程科学学报,2013,21(2):287-298.
[6] Bizindavyi L,Neale KW. Transfer Lengths and Bond Strengths for Composites Bonded to Concrete[J]. Journal of Composites for Construction,1999,3(4):153-160.
[7] Chajes MJ,Finch Jr WW,Januszka TF,et al. Bond and Force Transfer of Composites Material Plates Bonded to Concrete[J]. ACI Structural Journal,1996,93(2):208-217.
[8]何夕平,杨波,张运帅.预应力碳纤维布加固RC单向板的非线性有限元分析[J].合肥工业大学学报(自然科学版),2013,36(5):604-609.
[9] TALJSTEN B. Defining Anchor Lengths of Steel and CFRP Plates Bonded to Concrete[J]. International Journal of Adhesion and Adhesives,1997,17(4):319-327.
[10]Brosens K,van Gemert D. Anchoring Stresses between Concrete and Carbon Fibre Reinforced Laminates[J].Composite Construction,1998:181-186.
[11]J.G. Teng,S.T. Smith,J. Yao,et al. Intermediate Crackinduced Debonding in RC Beams and Slabs[J]. Construction and Building Materials,2003,17(6-7):447-462.
[12]纪铭.纤维增强材料补强混凝土结构技术应用研究[J].科技创新月刊,2016,29(2):119-121.
[13]Sharif A,Al-Sulaimani GJ,Basunbul IA,et al. Strengthening of Initially Loaded Reinforced Concrete Beams Using FRP plates[J]. Structural Journa,1994,91(2):160-168.
[14]Yun YC,Wu YF,Tang WC. Performance of FRP Bonding Systems under Fatigue Loading[J]. Engineering Structures,2008,30(11):3129-3140.
[15]Smith ST. FRP Anchors:Recent Advances in Research and Understanding. In:Proceedings,Second Asia-Pacific Conference on FRP in Structures. APFIS,2009:35-44.
[16]Smith S T,Teng J G. Shear-Bending Interaction in Debonding Failures of FRP-Plated RC Beams[J]. Advances in Structural Engineering,2003,6(3):183-199.