预应力FRP增强胶合木的预应力损失研究
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摘要
研究了预应力FRP增强胶合木梁的预应力损失,其中:FRP采用先张法施加预应力,并采用胶合与机械相结合的方式锚固于胶合木梁。分析表明:先张法FRP板的预应力损失主要包括垫块变形和木材弹性变形,FRP应力松弛、季节温差引起的预应力损失和木材蠕变引起的预应力损失。该研究基于平截面假定,通过胶合木梁的受力平衡与变形协调及材料本构模型,建立了每项预应力损失的计算公式,以及预应力损失后的胶合木梁反拱挠曲线方程,确定初始预应力限值范围;计算并分析了3组预应力CFRP增强胶合木梁的预应力损失值,应用反拱挠度实测值验证该研究计算理论。研究成果可为预应力FRP增强胶合木的设计与安全性评估提供理论参考。
This study analyzes the prestress loss of the pre-tensioned prestressed glulam beam reinforced with Fiber Reinforced Polymer(FRP), in which the prestressing FRP is fixed with both bonding and mechanical methods. The analysis results show that the prestress loss results from the deformation of the cushion block, elastic deformation of wood, stress relaxation of FRP, temperature difference and wood creep. Assuming that plane sections remain plane, the formulas to estimate each type of the prestress losses as well as the precamber after prestress loss, are put forward according to the force equilibrium and deformation compatibility of the beam and the constitutive model of each material. The prestress limits are further proposed. The prestress losses of three groups of glulam beams reinforced with prestressing CFRP plates were calculated and analyzed. Their computed precamber values were were used to verify the effectiveness of the proposed formulas. The research achievements can provide a theoretical reference for the engineering design and safety evaluation of the prestressed glulam beam.
This study analyzes the prestress loss of the pre-tensioned prestressed glulam beam reinforced with Fiber Reinforced Polymer(FRP), in which the prestressing FRP is fixed with both bonding and mechanical methods. The analysis results show that the prestress loss results from the deformation of the cushion block, elastic deformation of wood, stress relaxation of FRP, temperature difference and wood creep. Assuming that plane sections remain plane, the formulas to estimate each type of the prestress losses as well as the precamber after prestress loss, are put forward according to the force equilibrium and deformation compatibility of the beam and the constitutive model of each material. The prestress limits are further proposed. The prestress losses of three groups of glulam beams reinforced with prestressing CFRP plates were calculated and analyzed. Their computed precamber values were were used to verify the effectiveness of the proposed formulas. The research achievements can provide a theoretical reference for the engineering design and safety evaluation of the prestressed glulam beam.
引文
[1] 周先雁.胶合木梁抗弯承载力分析[J].建筑结构,2015,45(22):91-96.ZHOU Xianyan.Flexural capacity analysis of glulam beams [J].Building Structure,2015,45(22):91-96.(in Chinese)
[2] PLEVIRIS N,TRIANTAFILOU T C.FPR-reinforced wood as structural material [J].Journal of Materials in Civil Enginering,ASCE,1992,4(3):200-317.
[3] RAFTERY GM,WHELAN C.Low-grade glued laminated timber beams reinforced using improved arrangements of bonded-in GFRP rods [J].Construction & Building Materials,2014,52(52):209-220.
[4] LORENZIS LD,SCIALPI V,TEGOLA A L.Analytical and experimental study on bonded-in CFRP bars in glulam timber [J].Composites Part B:Engineering,2005,36(4):279-289.
[5] GLISOVIC I,STEVANOVIC B,PETROVIC M.Bending behavior of glulam beams reinforced with carbon FRP plates [J].Journal of Civil Engineering and Management,2015,21(7):923-932.
[6] RAFTERY G M,HARTE A M.Nonlinear numerical modelling of FRP reinforced glued laminated timber [J].Composites Part B:Engineering,2013,52(52):40-50.
[7] 杨会峰,刘伟庆.FRP增强胶合木梁的受弯性能研究[J].建筑结构学报,2007,28(1):64-71.YANG Huifeng,LIU Weiqing.Study on flexural behavior of FRP reinforced glulam beams [J].Journal of Building Structures,2007,28(1):64-71.(in Chinese)
[8] TRIANTAFILOU T,DESKOVIC N.Prestressed FRP sheets as external reinforcement of wood members [J].Journal of Structural Engineering,1992,18(5):1270-1284.
[9] DAGHER H,GRAY H,DAVIDS W,et al.Variable prestressing of FRP-reinforced glulam beams:methodology and behavior [C] //Proceedings of World Conference on Timber Engineering (SCTE 2010),Riva del Garda,Italy,2010.
[10] GUAN Z W,RODD P D,POPE D J.Study of glulam beams pre-stressed with pultruded GRP [J].Computers and Structures.2005,83(28-30):2476-2487.
[11] BRADY J F,HARTE A M.Flexural reinforcement of glue-laminated timber beams using prestressed FRP plates [C].// Proceedings of 4th International Conference on Advanced Composites in Construction (ACIC),Edinburgh,UK,2008.
[12] RODD P D,POPE D J.Prestressing as a means of better utilizing low quality wood in glued laminated beams [C].// Proceedings of the International Conference on Forest Products,Daejoen,Korea,2003.
[13] YANG H F,JU DD,LIU WQ,et al.Prestressed glulam beams reinforced with CFRP bars [J].Construction and Building Materials,2016,109:73-83.
[14] 陈爱军,等.BFRP 筋增强胶合木梁受力性能分析[J].中南林业科技大学学报,2019,39(3):107-113.CHEN Aijun,et al.Experimental study on mechanical behaviour of glulam timber beams reinforced with BFRP[J].Journal of Central south University of Forestry & Technology.2019,39(3):107-113.(in Chinese)
[15] BORRI A,CORRADI M,GRAZINI A.A method for flexural reinforcement of old wood beams with CFRP materials[J].Composites Part B Engineering,2005,36(2):143-153.
[16] 张晋,沈浩,高森,et al.体内预应力胶合木梁抗弯承载能力研究[J].湖南大学学报(自然科学版),2018,45(5):134-142.ZHANG Jin,SHEN Hao,GAO Sen,et al.Study pn flexural capacity of internal prestressed glulam beams[J].Journal of Hunan University (Natural sciences).2018,45(5):134-142.(in Chinese)
[17] 樊承谋.木结构基本原理[M].北京:中国建筑工业出版社,2008.FAN Chengmou.Basic Principles of Wood Structure [M].Beijing:China Building Industry Press,2008.(in Chinese)
[18] 谢力生.木结构材料与设计基础[M].北京:科学出版社,2013.XIE Lisheng.Wood Structure Material and Design Foundation [M].Beijing:Science Press,2013.(in Chinese)
[19] 召卓平.植物材料(木,竹)断裂力学[M].北京:科学出版社,2012.ZHAO Zhuoping.Fracture Mechanics of Plant Material Wood,Bamboo) [M].Beijing:Science Press,2012.(in Chinese)
[20] ACI440.4R-04,Prestressing Concrete Structures with FRP Tendons [S].America:ACI440 Committee.
[21] FRIDLEY A J,TANG R C,SOLTIS L A.Creep behavior model for structural lumber [J].Journal of Structural Engineering.1992,118(8):2261-2277.
[22] 杨建江,张雅琴.CFRP 筋预应力损失研究进展[J],四川建筑科学研究,2016,42(4):30-35.YANG Jianjiang,ZHANG Yaqin.Research progress of prestress loss of CFRP bars [J].Sichuan Building Science,2016,42(4):30-35.(in Chinese)
[23] GOWDA C,KORTESMAA M,RANTA MAUNUS A.Long term creep tests on timber beams in heated and non-heated environments [J].VTT Publications,1996,278:3-35.
[24] RANTA-MANUNUS A.Collection of creep data of timber [C].Proceedings of the International Council for Building Research Studies and Documentation 1991,Working Commission W 18A – Timber Structures CIB-W 18A/24-9-2.Oxford,United Kindom,1991.
[25] HOFFMEYER P,DENMARK R W.Mechano-sorptive creep mechanism of wood in compression and bending [J].Wood Science and Technology,1989,23(3):215-227.
[26] DUBOIS F,HUSSON J M,SAUVAT N,et al.Modeling of the viscoelastic mechano-sorptive behavior in wood [J].Mechanics of Time-Dependent Materials,2012,16(4):439-460.
[27] MARTENSSON A.Mechano-sorptive effects in wooden material [J].Wood Science and Technology.1994,28(6):437-449.
[28] HANHIJARVI H,HUNT D.Experimental indication of interaction between viscoelastic and mechano-sorptive [J].Wood Science and Technology.1998,32(1):57-70.
[29] HUNT D G,SHELTON C F.Progress in the analysis of creep in wood during concurrent moisture changes [J].Journal of Materials Science.1987,22(1):313-320.
[30] RANTA-MAUNUS A.The viscoelasticity of wood at varying moisture content [J].Wood Science and Technology.Springer-Verlag 1975,9:189-205.
[31] DUNOIS F,RANDRIAMBOLOLONA H,PETIT C.Creep in wood under variable climate conditions:numerical modeling and experimental validation [J].Mechanics of Time-Dependent Materials.2005,9(2):173-202.
[32] 孙训芳,方孝淑,关来泰.材料力学(I)[M].北京:高等教育出版社,2015.SUN Xunfang,FANG Xiaoshu,GUAN Laitai.Mechanics of materials [M].Beijing:Higher Education Press,2015.(in Chinese)
[2] PLEVIRIS N,TRIANTAFILOU T C.FPR-reinforced wood as structural material [J].Journal of Materials in Civil Enginering,ASCE,1992,4(3):200-317.
[3] RAFTERY GM,WHELAN C.Low-grade glued laminated timber beams reinforced using improved arrangements of bonded-in GFRP rods [J].Construction & Building Materials,2014,52(52):209-220.
[4] LORENZIS LD,SCIALPI V,TEGOLA A L.Analytical and experimental study on bonded-in CFRP bars in glulam timber [J].Composites Part B:Engineering,2005,36(4):279-289.
[5] GLISOVIC I,STEVANOVIC B,PETROVIC M.Bending behavior of glulam beams reinforced with carbon FRP plates [J].Journal of Civil Engineering and Management,2015,21(7):923-932.
[6] RAFTERY G M,HARTE A M.Nonlinear numerical modelling of FRP reinforced glued laminated timber [J].Composites Part B:Engineering,2013,52(52):40-50.
[7] 杨会峰,刘伟庆.FRP增强胶合木梁的受弯性能研究[J].建筑结构学报,2007,28(1):64-71.YANG Huifeng,LIU Weiqing.Study on flexural behavior of FRP reinforced glulam beams [J].Journal of Building Structures,2007,28(1):64-71.(in Chinese)
[8] TRIANTAFILOU T,DESKOVIC N.Prestressed FRP sheets as external reinforcement of wood members [J].Journal of Structural Engineering,1992,18(5):1270-1284.
[9] DAGHER H,GRAY H,DAVIDS W,et al.Variable prestressing of FRP-reinforced glulam beams:methodology and behavior [C] //Proceedings of World Conference on Timber Engineering (SCTE 2010),Riva del Garda,Italy,2010.
[10] GUAN Z W,RODD P D,POPE D J.Study of glulam beams pre-stressed with pultruded GRP [J].Computers and Structures.2005,83(28-30):2476-2487.
[11] BRADY J F,HARTE A M.Flexural reinforcement of glue-laminated timber beams using prestressed FRP plates [C].// Proceedings of 4th International Conference on Advanced Composites in Construction (ACIC),Edinburgh,UK,2008.
[12] RODD P D,POPE D J.Prestressing as a means of better utilizing low quality wood in glued laminated beams [C].// Proceedings of the International Conference on Forest Products,Daejoen,Korea,2003.
[13] YANG H F,JU DD,LIU WQ,et al.Prestressed glulam beams reinforced with CFRP bars [J].Construction and Building Materials,2016,109:73-83.
[14] 陈爱军,等.BFRP 筋增强胶合木梁受力性能分析[J].中南林业科技大学学报,2019,39(3):107-113.CHEN Aijun,et al.Experimental study on mechanical behaviour of glulam timber beams reinforced with BFRP[J].Journal of Central south University of Forestry & Technology.2019,39(3):107-113.(in Chinese)
[15] BORRI A,CORRADI M,GRAZINI A.A method for flexural reinforcement of old wood beams with CFRP materials[J].Composites Part B Engineering,2005,36(2):143-153.
[16] 张晋,沈浩,高森,et al.体内预应力胶合木梁抗弯承载能力研究[J].湖南大学学报(自然科学版),2018,45(5):134-142.ZHANG Jin,SHEN Hao,GAO Sen,et al.Study pn flexural capacity of internal prestressed glulam beams[J].Journal of Hunan University (Natural sciences).2018,45(5):134-142.(in Chinese)
[17] 樊承谋.木结构基本原理[M].北京:中国建筑工业出版社,2008.FAN Chengmou.Basic Principles of Wood Structure [M].Beijing:China Building Industry Press,2008.(in Chinese)
[18] 谢力生.木结构材料与设计基础[M].北京:科学出版社,2013.XIE Lisheng.Wood Structure Material and Design Foundation [M].Beijing:Science Press,2013.(in Chinese)
[19] 召卓平.植物材料(木,竹)断裂力学[M].北京:科学出版社,2012.ZHAO Zhuoping.Fracture Mechanics of Plant Material Wood,Bamboo) [M].Beijing:Science Press,2012.(in Chinese)
[20] ACI440.4R-04,Prestressing Concrete Structures with FRP Tendons [S].America:ACI440 Committee.
[21] FRIDLEY A J,TANG R C,SOLTIS L A.Creep behavior model for structural lumber [J].Journal of Structural Engineering.1992,118(8):2261-2277.
[22] 杨建江,张雅琴.CFRP 筋预应力损失研究进展[J],四川建筑科学研究,2016,42(4):30-35.YANG Jianjiang,ZHANG Yaqin.Research progress of prestress loss of CFRP bars [J].Sichuan Building Science,2016,42(4):30-35.(in Chinese)
[23] GOWDA C,KORTESMAA M,RANTA MAUNUS A.Long term creep tests on timber beams in heated and non-heated environments [J].VTT Publications,1996,278:3-35.
[24] RANTA-MANUNUS A.Collection of creep data of timber [C].Proceedings of the International Council for Building Research Studies and Documentation 1991,Working Commission W 18A – Timber Structures CIB-W 18A/24-9-2.Oxford,United Kindom,1991.
[25] HOFFMEYER P,DENMARK R W.Mechano-sorptive creep mechanism of wood in compression and bending [J].Wood Science and Technology,1989,23(3):215-227.
[26] DUBOIS F,HUSSON J M,SAUVAT N,et al.Modeling of the viscoelastic mechano-sorptive behavior in wood [J].Mechanics of Time-Dependent Materials,2012,16(4):439-460.
[27] MARTENSSON A.Mechano-sorptive effects in wooden material [J].Wood Science and Technology.1994,28(6):437-449.
[28] HANHIJARVI H,HUNT D.Experimental indication of interaction between viscoelastic and mechano-sorptive [J].Wood Science and Technology.1998,32(1):57-70.
[29] HUNT D G,SHELTON C F.Progress in the analysis of creep in wood during concurrent moisture changes [J].Journal of Materials Science.1987,22(1):313-320.
[30] RANTA-MAUNUS A.The viscoelasticity of wood at varying moisture content [J].Wood Science and Technology.Springer-Verlag 1975,9:189-205.
[31] DUNOIS F,RANDRIAMBOLOLONA H,PETIT C.Creep in wood under variable climate conditions:numerical modeling and experimental validation [J].Mechanics of Time-Dependent Materials.2005,9(2):173-202.
[32] 孙训芳,方孝淑,关来泰.材料力学(I)[M].北京:高等教育出版社,2015.SUN Xunfang,FANG Xiaoshu,GUAN Laitai.Mechanics of materials [M].Beijing:Higher Education Press,2015.(in Chinese)