混凝土连续梁板中无黏结CFRP筋应力增长规律
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摘要
使用CFRP(Carbon Fiber Reinforced Polymer)筋代替高强钢筋作为预应力筋,环氧涂层钢筋作为非预应力筋,可避免因预应力筋锈蚀而引起的结构物承载力下降和耐久性降低。把握无黏结CFRP筋应力增长规律是准确计算无黏结CFRP筋预应力混凝土梁(板)刚度、裂缝开展宽度及抗弯承载力的基础。针对无黏结预应力混凝土梁板在承载过程中无黏结CFRP筋不符合变形平截面假定的特点,应用等刚度法及弯矩-曲率非线性分析法,编制可用于分别考察正常使用极限状态和承载能力极限状态无黏结CFRP筋应力增长规律的计算程序。基于大量电算分析结果,得到受拉区非预应力筋配筋指标、预应力筋配筋指标、CFRP筋弹性模量、加载形式、跨高比、预应力筋合力点至受压区边缘的距离、受压区非预应力筋及受压翼缘等参数对正常使用阶段及正截面承载能力极限状态下连续梁板中无黏结CFRP筋应力增长的影响规律;建立部分预应力混凝土连续梁板中无黏结CFRP筋在正常使用阶段和正截面承载能力极限状态下应力增量的计算公式。
The bearing capacity and durability decline in structures caused by corrosion of prestressing tendons can be effectively avoided with CFRP(Carbon Fiber Reinforced Polymer) tendons used as prestressing tendons instead of high strength steel bars and with epoxy coated steel bars as non-prestressed reinforcements.Comprehension of the law of the stress increment of unbonded CFRP tendons is the basis to exactly calculate the stiffness,crack width and flexural load bearing capacity of the unbonded prestressed concrete beam and slab prestressed with CFRP tendons.Because the plane-section assumption is not applicable to unbonded tendons in loading of unbonded prestressed concrete beams and slabs,the constant stiffness method and moment-curvature nonlinear analysis method were used to compile the calculation programs of the law of the stress increment of unbonded CFRP tendons in serviceability limit states and ultimate limit states.On the basis of a large number of calculated results,the basic factors such as the tension zone indices,the non-prestressed reinforcement ratio,prestressing reinforcement ratio,modulus of elasticity of CFRP tendons,loading types,ratio of span to height and height from the concrete extreme fiber to the centroid of the prestressing tendons,and the parameters of the non-prestressed reinforcement of the compression zone and compression flange affecting the stress increment of unbonded CFRP tendons in continuous beams and slabs in serviceability limit states and normal-section ultimate limit states were presented.The calculation formulas of the stress increment of unbonded CFRP tendons in partially prestressed concrete continuous beams and slabs in serviceability limit states and normal-section ultimate limit states were proposed.
The bearing capacity and durability decline in structures caused by corrosion of prestressing tendons can be effectively avoided with CFRP(Carbon Fiber Reinforced Polymer) tendons used as prestressing tendons instead of high strength steel bars and with epoxy coated steel bars as non-prestressed reinforcements.Comprehension of the law of the stress increment of unbonded CFRP tendons is the basis to exactly calculate the stiffness,crack width and flexural load bearing capacity of the unbonded prestressed concrete beam and slab prestressed with CFRP tendons.Because the plane-section assumption is not applicable to unbonded tendons in loading of unbonded prestressed concrete beams and slabs,the constant stiffness method and moment-curvature nonlinear analysis method were used to compile the calculation programs of the law of the stress increment of unbonded CFRP tendons in serviceability limit states and ultimate limit states.On the basis of a large number of calculated results,the basic factors such as the tension zone indices,the non-prestressed reinforcement ratio,prestressing reinforcement ratio,modulus of elasticity of CFRP tendons,loading types,ratio of span to height and height from the concrete extreme fiber to the centroid of the prestressing tendons,and the parameters of the non-prestressed reinforcement of the compression zone and compression flange affecting the stress increment of unbonded CFRP tendons in continuous beams and slabs in serviceability limit states and normal-section ultimate limit states were presented.The calculation formulas of the stress increment of unbonded CFRP tendons in partially prestressed concrete continuous beams and slabs in serviceability limit states and normal-section ultimate limit states were proposed.
引文
[1]ZHENG W Z,BAI C X,Cheng D H.Experimental Studyon Behaviors of Unbonded Prestressed Concrete Beams Re-inforced with CFRP Tendons[J].Key Engineering Mate-rials,2009,400-402:567-573.
[2]Erki M A,Rizkalla S H.FRP Reinforcement for ConcreteStructures[J].ACI Concrete International,1993,15(6):48-53.
[3]American Concrete Institute.ACI 440.4R-04 PrestressingConcrete Structures with FRP Tendons[S].FarmingtonHills,Michigan:American Concrete Institute,2004.
[4]Naaman A E,Burns N,French C,Gamble W L,MattockA H.Stresses in Unbonded Prestressing Tendons at Ulti-mate:Recommendation[J].ACI Structural Journal,2002,99(4):518-529.
[5]张建伟,邓宗才,杜修力,汤惠工.预应力FRP在混凝土结构中的应用研究与发展[J].世界地震工程,2006,22(1):133-139.ZHANG Jian-wei,DENG Zong-cai,DU Xiu-li,TANGHui-gong.Studies on Application of Prestressed FRP inConcrete Structures[J].World Earthquake Engineering,2006,22(1):133-139.
[6]Harajli M H,Hijazi S A.Evaluation of the Ultimate SteelStress in Partially Prestressed Concrete Members[J].PCIJournal,1991,36(1):62-82.
[7]Naaman A E,Alkhairi F M.Stress at Ultimate in Un-bonded Post-tensioning Tendons:Part 2-proposed Meth-odology[J].ACI Structural Journal,1991,88(5):683-692.
[8]陶学康.无黏结预应力混凝土设计与施工[M].北京:地震出版社,1993.
[9]郑文忠,郑弦,王英.两跨预应力混凝土连续梁中无黏结筋极限应力计算方法[J].建筑结构,2005,35(7):67-71.ZHENG Wen-zhong,ZHENG Xian,WANG Ying.Calcu-lation of Ultimate Stress of Unbonded Tendons in Continu-ous Prestressed Concrete Beam[J].Building Structure,2005,35(7):67-71.
[10]程东辉,郑文忠.无黏结CFRP筋部分预应力混凝土连续梁试验与分析[J].复合材料学报,2008,25(5):104-113.CHENG Dong-hui,ZHENG Wen-zhong.Experiment andAnalysis on Partial Prestressed Concrete ContinuousBeams with Unbonded CFRP Tendon[J].Acta MateriaeCompositae Sinica,2008,25(5):104-113.
[11]郑文忠,解恒燕.与有黏结相协调的无黏结预应力混凝土梁刚度及裂缝宽度计算方法[J].建筑结构学报,2005,26(3):65-69.ZHENG Wen-zhong,XIE Heng-yan.Calculation Methodsof Stiffness and Crack Width of UPC Beam in Accordancewith Bonded PC Beam[J].Journal of Building Structures,2005,26(3):65-69.
[12]American Concrete Institute.ACI 440.1R-03 Guide forthe Design and Construction of Concrete Reinforced withFRP Bars[S].Farmington Hills,Michigan:AmericanConcrete Institute,2003.
[13]中国建筑科学研究院.JGJ92—2004无黏结预应力混凝土结构技术规程[S].北京:中国建筑工业出版社,2005.
[2]Erki M A,Rizkalla S H.FRP Reinforcement for ConcreteStructures[J].ACI Concrete International,1993,15(6):48-53.
[3]American Concrete Institute.ACI 440.4R-04 PrestressingConcrete Structures with FRP Tendons[S].FarmingtonHills,Michigan:American Concrete Institute,2004.
[4]Naaman A E,Burns N,French C,Gamble W L,MattockA H.Stresses in Unbonded Prestressing Tendons at Ulti-mate:Recommendation[J].ACI Structural Journal,2002,99(4):518-529.
[5]张建伟,邓宗才,杜修力,汤惠工.预应力FRP在混凝土结构中的应用研究与发展[J].世界地震工程,2006,22(1):133-139.ZHANG Jian-wei,DENG Zong-cai,DU Xiu-li,TANGHui-gong.Studies on Application of Prestressed FRP inConcrete Structures[J].World Earthquake Engineering,2006,22(1):133-139.
[6]Harajli M H,Hijazi S A.Evaluation of the Ultimate SteelStress in Partially Prestressed Concrete Members[J].PCIJournal,1991,36(1):62-82.
[7]Naaman A E,Alkhairi F M.Stress at Ultimate in Un-bonded Post-tensioning Tendons:Part 2-proposed Meth-odology[J].ACI Structural Journal,1991,88(5):683-692.
[8]陶学康.无黏结预应力混凝土设计与施工[M].北京:地震出版社,1993.
[9]郑文忠,郑弦,王英.两跨预应力混凝土连续梁中无黏结筋极限应力计算方法[J].建筑结构,2005,35(7):67-71.ZHENG Wen-zhong,ZHENG Xian,WANG Ying.Calcu-lation of Ultimate Stress of Unbonded Tendons in Continu-ous Prestressed Concrete Beam[J].Building Structure,2005,35(7):67-71.
[10]程东辉,郑文忠.无黏结CFRP筋部分预应力混凝土连续梁试验与分析[J].复合材料学报,2008,25(5):104-113.CHENG Dong-hui,ZHENG Wen-zhong.Experiment andAnalysis on Partial Prestressed Concrete ContinuousBeams with Unbonded CFRP Tendon[J].Acta MateriaeCompositae Sinica,2008,25(5):104-113.
[11]郑文忠,解恒燕.与有黏结相协调的无黏结预应力混凝土梁刚度及裂缝宽度计算方法[J].建筑结构学报,2005,26(3):65-69.ZHENG Wen-zhong,XIE Heng-yan.Calculation Methodsof Stiffness and Crack Width of UPC Beam in Accordancewith Bonded PC Beam[J].Journal of Building Structures,2005,26(3):65-69.
[12]American Concrete Institute.ACI 440.1R-03 Guide forthe Design and Construction of Concrete Reinforced withFRP Bars[S].Farmington Hills,Michigan:AmericanConcrete Institute,2003.
[13]中国建筑科学研究院.JGJ92—2004无黏结预应力混凝土结构技术规程[S].北京:中国建筑工业出版社,2005.
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