二次张拉低回缩预应力锚具及锚下应力分析
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摘要
目前,我国对大跨径预应力混凝土箱梁桥腹板中的竖向预应力通常是采用张拉精轧螺纹钢的方式来实现,但精轧螺纹钢YGM锚固体系都存在锚具实际回缩损失大、安装的精度要求高、精轧螺纹钢筋易被拉断和压浆质量不够好等等缺陷。为此,湖南大学桥梁工程研究所和湖南湘潭欧之姆预应力锚具有限公司共同研制出一种“二次张拉低回缩钢绞线竖向预应力锚固系统”,使之得到有效的改善。为了验证这种新型锚具的工作性能,本文进行了以下几个方面的研究：
1.从受力、施工现场的条件以及可靠度等方面考虑,本文确定螺母的最佳长度为25mm。
2.单孔二次张拉低回缩预应力锚具螺母外侧最大应力位于与垫板相接触的受压端,往自由端逐渐减小,在自由端轴向应力转为拉应力、环向应力转为压应力。
3.设计了采用二次张拉低回缩预应力锚具的矩形梁试验,将理论计算结果分别与传统夹片式锚具锚下应力场、新型二次张拉低回缩预应力锚具锚下应力场进行对比,发现在张拉过程中三者锚下应力场的变化规律一致,因此单孔二次张拉低回缩预应力锚具锚下构造可完全与传统夹片式锚具相同。
4.通过实桥测试对低回缩二次张拉预应力锚具应用于腹板竖向预应力的预应力损失进行了测试,重点测试了其由于接缝压缩、锚具变形及回缩引起的预应力损失值、弹性压缩值、松弛损失值、收缩徐变损失值,并对影响预应力损失的因素进行了分析。
在本文的最后,对新型二次张拉低回缩预应力锚具的发展和进一步研究提出了建议和注意的问题。
At present, the vertical web's pre-stress of the long-span prestressed concrete box-girder bridge is usually achieved through straining steel mills in China. However, steel mill YGM anchor system has so many deficiencies such as great back losses, high-demanding of precision in installation, possibility of pulling off the stell mill, inferiority of the mudjack and so on. To improve that effectively, the Institute of Bridge Engineering in Hunan University, together with Hunan Xiangtan OHM Prestressed Anchorage Company, has developed a "Twice Pre-stressed and Low Retracting Strand Vertical Web in Tension Anchorage System". In order to verify the performance of this new type of anchorage, this paper has made the following researches with the low retracting twice pre-stressed anchorage as subject of study:
1. Considing the forces, the conditions in constructing site, and the reliability theory, it is suggested that 25mm is the best length of the nut in this paper.
2. The single low retracting twice pre-stressed anchorage nut's maximum stress is at the compressive end contact with the backing plate under the anchor. And the closer to the free end the smaller stress is. At the free end, the axial stress transforms to tensile stress and the hoop stress turns to pressure stress.
3. A scaled test of rectangular beam using single low retracting pre-stress anchorage was constructed and experimented. Based on the strain measurements, the stress field under the traditional anchorage and the new low retracting pre-stressing anchorage system are obtained, and the results of the tests are consistent with the theoretical calculation ones. Therefore, compared with the traditional anchorage, the single low retracting pre-stress anchorage has the same contiguration under the anchor.
4. Research on actual bridge has been made to measure pre-stress lose of vertical prestressing force in web which low retracting twice pre-stressed anchorage has been adopted. The emphases have been paid to the pre-stress lose induced by compression of joint, deformation and retraction of anchorage, elastic compression of concrete, lose through creep and shrinkage of concrete. And analysis has been made to study the factors influencing pre-stress lose.
At last, this paper has put forward some advices and noticable problems for the new low retracting twice pre-stressed anchorage's further development.
1.从受力、施工现场的条件以及可靠度等方面考虑,本文确定螺母的最佳长度为25mm。
2.单孔二次张拉低回缩预应力锚具螺母外侧最大应力位于与垫板相接触的受压端,往自由端逐渐减小,在自由端轴向应力转为拉应力、环向应力转为压应力。
3.设计了采用二次张拉低回缩预应力锚具的矩形梁试验,将理论计算结果分别与传统夹片式锚具锚下应力场、新型二次张拉低回缩预应力锚具锚下应力场进行对比,发现在张拉过程中三者锚下应力场的变化规律一致,因此单孔二次张拉低回缩预应力锚具锚下构造可完全与传统夹片式锚具相同。
4.通过实桥测试对低回缩二次张拉预应力锚具应用于腹板竖向预应力的预应力损失进行了测试,重点测试了其由于接缝压缩、锚具变形及回缩引起的预应力损失值、弹性压缩值、松弛损失值、收缩徐变损失值,并对影响预应力损失的因素进行了分析。
在本文的最后,对新型二次张拉低回缩预应力锚具的发展和进一步研究提出了建议和注意的问题。
At present, the vertical web's pre-stress of the long-span prestressed concrete box-girder bridge is usually achieved through straining steel mills in China. However, steel mill YGM anchor system has so many deficiencies such as great back losses, high-demanding of precision in installation, possibility of pulling off the stell mill, inferiority of the mudjack and so on. To improve that effectively, the Institute of Bridge Engineering in Hunan University, together with Hunan Xiangtan OHM Prestressed Anchorage Company, has developed a "Twice Pre-stressed and Low Retracting Strand Vertical Web in Tension Anchorage System". In order to verify the performance of this new type of anchorage, this paper has made the following researches with the low retracting twice pre-stressed anchorage as subject of study:
1. Considing the forces, the conditions in constructing site, and the reliability theory, it is suggested that 25mm is the best length of the nut in this paper.
2. The single low retracting twice pre-stressed anchorage nut's maximum stress is at the compressive end contact with the backing plate under the anchor. And the closer to the free end the smaller stress is. At the free end, the axial stress transforms to tensile stress and the hoop stress turns to pressure stress.
3. A scaled test of rectangular beam using single low retracting pre-stress anchorage was constructed and experimented. Based on the strain measurements, the stress field under the traditional anchorage and the new low retracting pre-stressing anchorage system are obtained, and the results of the tests are consistent with the theoretical calculation ones. Therefore, compared with the traditional anchorage, the single low retracting pre-stress anchorage has the same contiguration under the anchor.
4. Research on actual bridge has been made to measure pre-stress lose of vertical prestressing force in web which low retracting twice pre-stressed anchorage has been adopted. The emphases have been paid to the pre-stress lose induced by compression of joint, deformation and retraction of anchorage, elastic compression of concrete, lose through creep and shrinkage of concrete. And analysis has been made to study the factors influencing pre-stress lose.
At last, this paper has put forward some advices and noticable problems for the new low retracting twice pre-stressed anchorage's further development.
引文
[1]湖南大学土木工程学院,中交公路规划设计院.混凝土桥梁裂缝成因分析研究报告.湖南：湖南大学,1998,1-7
[2]JGJ 85-2002预应力筋用锚具、夹具和连接器应用技术规程.北京：中国建筑工业出版社出版,2002,7-8
[3]GB/T 14370-2000预应力筋用锚具、夹具和连接器.北京：中国建筑工业出版社出版,2000,4-6
[4]邵旭东.桥梁工程.北京：人民交通出版社,2004,1-20
[5]邵旭东.胡建华桥梁设计百问.第二版.北京：人民交通出版社,2005,50-132
[6]蒋田勇.碳纤维预应力筋及拉索锚固系统的试验研究和理论分析.[湖南大学博士学位论文],2008,4
[7]庄茁,朱万旭等.预应力结构锚固—接触力学与工程应用.北京：科学出版社,2006,4-5,145-146,168
[8]P. W. Abeles, B. K. Bardhan-Roy, F. H. Turner.etal.预应力混凝土设计手册.第2版.北京：人民交通出版社,1983,546-601
[9]JT 329.2-1997公路桥梁预应力钢绞线用锚具、连接器试验方法及检验规则.北京：中国建筑工业出版社出版,1997,126-128
[10]GB50010-2002混凝土结构设计规范.北京：中国建筑工业出版社出版,2002,26-39
[11]JTGD62-2004公路钢筋混凝土及预应力混凝土桥涵设计规范.北京：中交公路规划设计院,2004,54-55
[12]JT/T 329.1-1997公路桥梁预应力钢绞线用YM锚具、连接器规格系列.北京：中国建筑工业出版社出版,1997,113-116
[13]方志,汪剑.预应力混凝土箱梁桥竖向预应力损失的实测与分析.土木工程学报,2006,(5),78-84
[14]Yail J.Kim, Chen Shi, Mark F.Green.Ductility and cracking behavior of prestressed concrete beams strengthened with prestressed CFRP sheets.Journal of Composites for Construction,2008,274-283
[15]A.Al-Mayah, K.Soudki, A.Plumtree.Effect of sleeve material on Interfacial contact behavior of CFRP-metal couples. Journal of Materials in Civil Engineering,2006,825-830
[16]Byung Hwan Oh, M.ASCE, Eui Sung Kim,Young CheolChoi.Theoretical analysis of transfer lengths in pretensioned prestressed Concrete members. Journal of Engineering Mechanics,2006,1057-1066
[17]Mohamad Ali-Ahmad,Kolluru Subramaniam, Michel Ghosn.Experimental investigation and fracture analysis of debondingbetween concrete and FRP sheets. Journal of Engineering Mechanics,2006,914-923
[18]Siddhwartha Mandal, Amir Fam. Modeling of prestressed concrete-Filled circular composite tubes subjected to bending and axial loads. Journal of Structural Engineering,2006,449-459
[19]苏强,龙跃,陆明俊.钢绞线竖向预应力锚固体系的研究.城市道路与防洪,2007,2(2),97-99
[20]蒋天勇,方志.CFRP预应力筋夹片式锚具的试验研究.土木工程学报,2008,2(2),60-69
[21]耿皓.混凝土局部受压承载力计算方法浅析.哈尔滨师范大学自然科学学报,2004,5(5),43-45
[22]孔庆华,王四玲,谢强.夹片式单孔预应力锚具的结构分析.精密制造与自动化,2005(3),10-11
[23]赵通,左德元,童建刚.夹片式锚固体系锥角的有限元参数化设计.西南交通大学学报,2004,10(5),614-617
[24]王国玉,刘东青.预应力锚具的弹塑性有限元分析.辽宁工程技术大学学报,2005,12,96-98
[25]陶浩,段红杰,刘建秀.预应力锚具的强度性能破坏研究.机械设计,2003,8(8),13-15
[26]朱万旭,郑晓龙,王守海.预应力锚具有限元分析技术初探,2005,3,251-258
[27]Rigoberto Burgueno, Mahmoodul Haq. Development length of prestressing strands in precast/prestressed girders using self compacting concrete. structures, 2005,1-8
[28]Hung-Liang (Roger) Chen, Komwut Wissawapaisal. Application ofwigner-ville transform to evaluate tensile forces in seven-wire prestressing strands. Journal of Engineering Mchanics,2002,1206-1214
[29]John Sun, Rafael Manzanarez, Marwan Nader. Design of looping cable anchorage system for new San Francisco-Oakland bay bridge main suspension span. Journal of Bridge Engineering,2002,315-324
[30]Hung-Liang (Roger) Chen, Komwut Wissawapaisal. Measurement of tensile forces in a seven-wire prestressing strand using stress waves. Journal of Engineering Mechanics,2001,599-606
[31]郑文忠,张吉柱.密布预应力束锚具下混凝土局部受压承载力计算方法.建筑结构学报,2004,8(4),60-65
[32]徐建红,范厚彬.锚具夹片回缩引起预应力损失的研究. 公路,2006,7(7),93-95
[33]韩利.预应力钢筋混凝土中钢筋预应力损失的分类计算及控制法.森林工程,2001,9(5),38-39
[34]陶浩,段红杰,刘建秀.预应力锚具的强度性能破坏研究.机械设计,2003,8(8),13-15
[35]于滨,冯大斌等.QMV新型锚具的研究与应用.施工技术,2001,7(7),31-33
[36]王刚,王志明.STM锚具锚下结构分析与设计.铁道学报,2000,6(3),84-87
[37]朱万旭,黄颖,苏均等.大直径钢绞线的预应力锚具.建筑技术,2003(12),903-904
[38]李斌.二次张拉钢绞线技术应用于箱梁腹板竖向预应力的研究：[湖南大学硕士学位论文].长沙：湖南大学土木工程学院,2009,33-38
[39]张鹏,邓宇.单根碳纤维塑料筋新型锚具的研制.施工技术,2003,11(11),32-33
[40]N.J.Gardner M.J.Lockman.Design provisions for Drying Shrinkage and Creep of Normal-Strength Conctete.ACI Materials Journal.2001, (4):159-167
[41]Taketo Uomoto, Hiroshi Mutsuyoshi, Futoshi Katsuki, Sudhir Misra.Use of fiber reinforced polymer composites as reinforcing material for concrete. Journal Msterials in Civil Engineering,2002,191-209
[42]B.Benmokrane, P.Wang, T.R.Gentry, S.Faza. Tests methods to determine properties of FRP Rods for concrete structures. Composites in Construction, 1997,75-83
[43]周明华.影响夹片式锚具锚固性能的综合因素.桥梁建设,2001(2),58-64
[44]詹界东,杜修力,邓宗才.预应力FRP筋锚具的研究与发展.工业建筑2006(12),65-68
[45]吴志刚,王秀杰.对预应力锚具静载试验的探讨.安徽建筑,2007(3),176-178
[46]于滨,朱莹,陈茜,架贵臣.多种规格预应力筋锚具、夹具研究与试验.第八届后张预应力学术交流会论文,2004,92-100
[2]JGJ 85-2002预应力筋用锚具、夹具和连接器应用技术规程.北京：中国建筑工业出版社出版,2002,7-8
[3]GB/T 14370-2000预应力筋用锚具、夹具和连接器.北京：中国建筑工业出版社出版,2000,4-6
[4]邵旭东.桥梁工程.北京：人民交通出版社,2004,1-20
[5]邵旭东.胡建华桥梁设计百问.第二版.北京：人民交通出版社,2005,50-132
[6]蒋田勇.碳纤维预应力筋及拉索锚固系统的试验研究和理论分析.[湖南大学博士学位论文],2008,4
[7]庄茁,朱万旭等.预应力结构锚固—接触力学与工程应用.北京：科学出版社,2006,4-5,145-146,168
[8]P. W. Abeles, B. K. Bardhan-Roy, F. H. Turner.etal.预应力混凝土设计手册.第2版.北京：人民交通出版社,1983,546-601
[9]JT 329.2-1997公路桥梁预应力钢绞线用锚具、连接器试验方法及检验规则.北京：中国建筑工业出版社出版,1997,126-128
[10]GB50010-2002混凝土结构设计规范.北京：中国建筑工业出版社出版,2002,26-39
[11]JTGD62-2004公路钢筋混凝土及预应力混凝土桥涵设计规范.北京：中交公路规划设计院,2004,54-55
[12]JT/T 329.1-1997公路桥梁预应力钢绞线用YM锚具、连接器规格系列.北京：中国建筑工业出版社出版,1997,113-116
[13]方志,汪剑.预应力混凝土箱梁桥竖向预应力损失的实测与分析.土木工程学报,2006,(5),78-84
[14]Yail J.Kim, Chen Shi, Mark F.Green.Ductility and cracking behavior of prestressed concrete beams strengthened with prestressed CFRP sheets.Journal of Composites for Construction,2008,274-283
[15]A.Al-Mayah, K.Soudki, A.Plumtree.Effect of sleeve material on Interfacial contact behavior of CFRP-metal couples. Journal of Materials in Civil Engineering,2006,825-830
[16]Byung Hwan Oh, M.ASCE, Eui Sung Kim,Young CheolChoi.Theoretical analysis of transfer lengths in pretensioned prestressed Concrete members. Journal of Engineering Mechanics,2006,1057-1066
[17]Mohamad Ali-Ahmad,Kolluru Subramaniam, Michel Ghosn.Experimental investigation and fracture analysis of debondingbetween concrete and FRP sheets. Journal of Engineering Mechanics,2006,914-923
[18]Siddhwartha Mandal, Amir Fam. Modeling of prestressed concrete-Filled circular composite tubes subjected to bending and axial loads. Journal of Structural Engineering,2006,449-459
[19]苏强,龙跃,陆明俊.钢绞线竖向预应力锚固体系的研究.城市道路与防洪,2007,2(2),97-99
[20]蒋天勇,方志.CFRP预应力筋夹片式锚具的试验研究.土木工程学报,2008,2(2),60-69
[21]耿皓.混凝土局部受压承载力计算方法浅析.哈尔滨师范大学自然科学学报,2004,5(5),43-45
[22]孔庆华,王四玲,谢强.夹片式单孔预应力锚具的结构分析.精密制造与自动化,2005(3),10-11
[23]赵通,左德元,童建刚.夹片式锚固体系锥角的有限元参数化设计.西南交通大学学报,2004,10(5),614-617
[24]王国玉,刘东青.预应力锚具的弹塑性有限元分析.辽宁工程技术大学学报,2005,12,96-98
[25]陶浩,段红杰,刘建秀.预应力锚具的强度性能破坏研究.机械设计,2003,8(8),13-15
[26]朱万旭,郑晓龙,王守海.预应力锚具有限元分析技术初探,2005,3,251-258
[27]Rigoberto Burgueno, Mahmoodul Haq. Development length of prestressing strands in precast/prestressed girders using self compacting concrete. structures, 2005,1-8
[28]Hung-Liang (Roger) Chen, Komwut Wissawapaisal. Application ofwigner-ville transform to evaluate tensile forces in seven-wire prestressing strands. Journal of Engineering Mchanics,2002,1206-1214
[29]John Sun, Rafael Manzanarez, Marwan Nader. Design of looping cable anchorage system for new San Francisco-Oakland bay bridge main suspension span. Journal of Bridge Engineering,2002,315-324
[30]Hung-Liang (Roger) Chen, Komwut Wissawapaisal. Measurement of tensile forces in a seven-wire prestressing strand using stress waves. Journal of Engineering Mechanics,2001,599-606
[31]郑文忠,张吉柱.密布预应力束锚具下混凝土局部受压承载力计算方法.建筑结构学报,2004,8(4),60-65
[32]徐建红,范厚彬.锚具夹片回缩引起预应力损失的研究. 公路,2006,7(7),93-95
[33]韩利.预应力钢筋混凝土中钢筋预应力损失的分类计算及控制法.森林工程,2001,9(5),38-39
[34]陶浩,段红杰,刘建秀.预应力锚具的强度性能破坏研究.机械设计,2003,8(8),13-15
[35]于滨,冯大斌等.QMV新型锚具的研究与应用.施工技术,2001,7(7),31-33
[36]王刚,王志明.STM锚具锚下结构分析与设计.铁道学报,2000,6(3),84-87
[37]朱万旭,黄颖,苏均等.大直径钢绞线的预应力锚具.建筑技术,2003(12),903-904
[38]李斌.二次张拉钢绞线技术应用于箱梁腹板竖向预应力的研究：[湖南大学硕士学位论文].长沙：湖南大学土木工程学院,2009,33-38
[39]张鹏,邓宇.单根碳纤维塑料筋新型锚具的研制.施工技术,2003,11(11),32-33
[40]N.J.Gardner M.J.Lockman.Design provisions for Drying Shrinkage and Creep of Normal-Strength Conctete.ACI Materials Journal.2001, (4):159-167
[41]Taketo Uomoto, Hiroshi Mutsuyoshi, Futoshi Katsuki, Sudhir Misra.Use of fiber reinforced polymer composites as reinforcing material for concrete. Journal Msterials in Civil Engineering,2002,191-209
[42]B.Benmokrane, P.Wang, T.R.Gentry, S.Faza. Tests methods to determine properties of FRP Rods for concrete structures. Composites in Construction, 1997,75-83
[43]周明华.影响夹片式锚具锚固性能的综合因素.桥梁建设,2001(2),58-64
[44]詹界东,杜修力,邓宗才.预应力FRP筋锚具的研究与发展.工业建筑2006(12),65-68
[45]吴志刚,王秀杰.对预应力锚具静载试验的探讨.安徽建筑,2007(3),176-178
[46]于滨,朱莹,陈茜,架贵臣.多种规格预应力筋锚具、夹具研究与试验.第八届后张预应力学术交流会论文,2004,92-100