锈蚀钢筋与混凝土不协调变形量化方法及对构件受弯性能的影响
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摘要
锈蚀黏结退化会引起钢筋与混凝土之间的不协调变形,导致构件受弯性能退化。提出了一种锈蚀钢筋与混凝土不协调变形量化方法,该方法将黏结退化表示成锈蚀率的函数,基于有效黏结力传递规律确定受弯构件黏结滑移区范围,进而构建黏结滑移区内整体变形关系实现对不协调变形的量化。该方法可用于锈蚀RC梁受弯承载力计算评估,能综合考虑锈蚀截面损失、黏结退化以及钢筋端锚失效等影响,具有较高的精度。研究表明:不协调变形受钢筋锈蚀和荷载的影响;锈蚀率低于7%时,构件不会出现不协调变形;锈蚀率越高,不协调变形出现时对应的荷载越低,对构件受弯承载力退化的影响越显著;锈蚀率大于15%时,不协调变形会提早出现,变形协调系数迅速趋于某一恒定值,由其引起的承载力退化量基本保持不变。
Corrosion-induced bond degradation leads to incompatible strain between steel rebar and concrete, resulting in the deterioration of flexural behavior of beams. An analytical model was proposed in this paper to quantify the incompatible strain between corroded steel rebar and concrete. The bond degradation was considered as the function of the corrosion degree of steel. The slipping region within the corroded RC beams was firstly determined based on the shifting rule of effective bond region. Then, the global deformation relationship between steel rebar and concrete within the slipping region was established to accomplish the quantification of incompatible strain. The proposed model can be employed to predict the flexural capacity of corroded RC beams. The effects of corrosion-induced area loss of steel rebar, bond degradation and the anchorage failure of steel rebar can be considered in the prediction. The proposed model is verified to have high accuracy. Results show that the incompatible strain is affected by the corrosion loss and loading state. No incompatible strain appears in the slightly corroded members until the corrosion loss exceeds 7%. Beyond this, a higher corrosion degree leads to a smaller load at the initiation of incompatible strain and more significant degradation of the flexural capacity of members. As the corrosion loss is greater than 15%, the incompatible strain appears prematurely and approaches rapidly to a constant value, but its effects on the flexural capacity remain almost unchanged.
Corrosion-induced bond degradation leads to incompatible strain between steel rebar and concrete, resulting in the deterioration of flexural behavior of beams. An analytical model was proposed in this paper to quantify the incompatible strain between corroded steel rebar and concrete. The bond degradation was considered as the function of the corrosion degree of steel. The slipping region within the corroded RC beams was firstly determined based on the shifting rule of effective bond region. Then, the global deformation relationship between steel rebar and concrete within the slipping region was established to accomplish the quantification of incompatible strain. The proposed model can be employed to predict the flexural capacity of corroded RC beams. The effects of corrosion-induced area loss of steel rebar, bond degradation and the anchorage failure of steel rebar can be considered in the prediction. The proposed model is verified to have high accuracy. Results show that the incompatible strain is affected by the corrosion loss and loading state. No incompatible strain appears in the slightly corroded members until the corrosion loss exceeds 7%. Beyond this, a higher corrosion degree leads to a smaller load at the initiation of incompatible strain and more significant degradation of the flexural capacity of members. As the corrosion loss is greater than 15%, the incompatible strain appears prematurely and approaches rapidly to a constant value, but its effects on the flexural capacity remain almost unchanged.
引文
[1] ZHAO Y, YU J, HU B, et al. Crack shape and rust distribution in corrosion-induced cracking concrete[J]. Corrosion Science, 2012, 55: 385-393.
[2] FANG C, LUNDGREN K, CHEN L, et al. Corrosion influence on bond in reinforced concrete[J]. Cement and Concrete Research, 2004, 34(11): 2159-2167.
[3] AUYEUNG Y, BALAGURU P, CHUNG L. Bond behavior of corroded reinforcement bars[J]. ACI Materials Journal, 2000, 97(2): 214-220.
[4] CHOI Y S, YI S T, KIM M Y, et al. Effect of corrosion method of the reinforcing bar on bond characteristics in reinforced concrete specimens[J]. Construction and Building Materials, 2014, 54: 180-189.
[5] 肖建庄, 雷斌. 锈蚀钢筋与再生混凝土间粘结性能试验研究[J]. 建筑结构学报, 2011, 32(1): 58- 62. (XIAO Jianzhuang, LEI Bin. Experimental study on bond behavior between corroded steel bars and recycled concret[J]. Journal of Building Structures, 2011, 32(1): 58- 62. (in Chinese))
[6] BHARGAVA K, GHOSH A K, MORI Y, et al. Suggested empirical models for corrosion-induced bond degradation in reinforced concrete[J]. Journal of Structural Engineering, 2008, 134(2): 221-230.
[7] CORONELLI D. Corrosion cracking and bond strength modeling for corroded bars in reinforced concrete[J]. ACI Structural Journal, 2002, 99(3): 267-276.
[8] 卫军, 徐港, 王青. 锈蚀钢筋与混凝土粘结应力模型研究[J]. 建筑结构学报, 2008, 29(1): 112-116. (WEI Jun, XU Gang, WANG Qing. Bond strength modeling for corroded reinforcing bar in concrete[J]. Journal of Building Structures, 2008, 29(1): 112-116. (in Chinese))
[9] DEKOSTER M, BUYLE-BODIN F,MAUREL O,et al. Modelling of the flexural behaviour of RC beams subjected to localised and uniform corrosion[J]. Engineering Structures, 2003, 25(10): 1333-1341.
[10] 金伟良, 夏晋, 蒋遨宇, 等. 锈蚀钢筋混凝土梁受弯承载力计算模型[J]. 土木工程学报, 2009, 42(11): 64-70. (JIN Weiliang, XIA Jin, JIANG Aoyu, et al. Flexural capacity of corrosion-damaged RC beams[J]. China Civil Engineering Journal, 2009, 42(11): 64-70. (in Chinese))
[11] 张建仁, 张克波, 彭晖, 等. 锈蚀钢筋混凝土矩形梁正截面抗弯承载力计算方法[J]. 中国公路学报, 2009, 22(3): 45-51. (ZHANG Jianren, ZHANG Kebo, PENG Hui, et al. Calculation method of normal section flexural capacity of corroded reinforced concrete rectangular beams[J]. China Journal of Highway and Transport, 2009, 22(3): 45-51. (in Chinese))
[12] AZAD A K, AHMAD S, AZHER S A. Residual strength of corrosion-damaged reinforced concrete beams[J]. ACI Materials Journal, 2007, 104(1): 40- 47.
[13] NAAMAN A E, BURNS N, FRENCH C, et al. Stresses in unbonded prestressing tendons at ultimate: recommendation[J]. ACI Structural Journal, 2002, 99(4): 518-529.
[14] LONG X, TAN K H, LEE C K. Bond stress-slip prediction under pullout and dowel action in reinforced concrete joints[J]. ACI Structural Journal, 2014, 111(4): 977-987.
[15] EL-TAWIL S, OGUNC C, OKEIL A, et al. Static and fatigue analysis of RC beams strengthened with CFRP laminates[J]. Journal of Composites for Construction, 2001, 5(4): 258-267.
[16] COLLINS M, MITCHELL D. Prestessed concrete struture[M]. Englewood Cliffs, NJ: Prentice Hall, 1991.
[17] CAIRNS J, ABDULLAH R B. Bond strength of black and epoxy-coated reinforcement: a theoretical approach[J]. ACI Materials Journal, 1996, 93(4): 362-369.
[18] GIURIANI E, PLIZZARI G, SCHUMM C. Role of stirrups and residual tensile strength of cracked concrete on bond[J]. Journal of Structural Engineering, 1991, 117(1): 1-18.
[19] WANG X, LIU X. Modeling bond strength of corroded reinforcement without stirrups[J]. Cement and Concrete Research, 2004, 34(8): 1331-1339.
[20] American Concrete Institute. Building code requirements for structural concrete and commentary: ACI 318- 08[S]. Fsrmington Hills,MI: ACI, 2008.
[21] CEB-FIP. FIB model code for concrete structures: CEB-FIP: 2010[S]. Lausanne, Switzerland: fib, 2010.
[22] WANG L, MA Y, DING W, et al. Comparative study of flexural behavior of corroded beams with different types of steel bars[J]. Journal of Performance of Constructed Facilities, 2015, 29(6): 04014163.
[2] FANG C, LUNDGREN K, CHEN L, et al. Corrosion influence on bond in reinforced concrete[J]. Cement and Concrete Research, 2004, 34(11): 2159-2167.
[3] AUYEUNG Y, BALAGURU P, CHUNG L. Bond behavior of corroded reinforcement bars[J]. ACI Materials Journal, 2000, 97(2): 214-220.
[4] CHOI Y S, YI S T, KIM M Y, et al. Effect of corrosion method of the reinforcing bar on bond characteristics in reinforced concrete specimens[J]. Construction and Building Materials, 2014, 54: 180-189.
[5] 肖建庄, 雷斌. 锈蚀钢筋与再生混凝土间粘结性能试验研究[J]. 建筑结构学报, 2011, 32(1): 58- 62. (XIAO Jianzhuang, LEI Bin. Experimental study on bond behavior between corroded steel bars and recycled concret[J]. Journal of Building Structures, 2011, 32(1): 58- 62. (in Chinese))
[6] BHARGAVA K, GHOSH A K, MORI Y, et al. Suggested empirical models for corrosion-induced bond degradation in reinforced concrete[J]. Journal of Structural Engineering, 2008, 134(2): 221-230.
[7] CORONELLI D. Corrosion cracking and bond strength modeling for corroded bars in reinforced concrete[J]. ACI Structural Journal, 2002, 99(3): 267-276.
[8] 卫军, 徐港, 王青. 锈蚀钢筋与混凝土粘结应力模型研究[J]. 建筑结构学报, 2008, 29(1): 112-116. (WEI Jun, XU Gang, WANG Qing. Bond strength modeling for corroded reinforcing bar in concrete[J]. Journal of Building Structures, 2008, 29(1): 112-116. (in Chinese))
[9] DEKOSTER M, BUYLE-BODIN F,MAUREL O,et al. Modelling of the flexural behaviour of RC beams subjected to localised and uniform corrosion[J]. Engineering Structures, 2003, 25(10): 1333-1341.
[10] 金伟良, 夏晋, 蒋遨宇, 等. 锈蚀钢筋混凝土梁受弯承载力计算模型[J]. 土木工程学报, 2009, 42(11): 64-70. (JIN Weiliang, XIA Jin, JIANG Aoyu, et al. Flexural capacity of corrosion-damaged RC beams[J]. China Civil Engineering Journal, 2009, 42(11): 64-70. (in Chinese))
[11] 张建仁, 张克波, 彭晖, 等. 锈蚀钢筋混凝土矩形梁正截面抗弯承载力计算方法[J]. 中国公路学报, 2009, 22(3): 45-51. (ZHANG Jianren, ZHANG Kebo, PENG Hui, et al. Calculation method of normal section flexural capacity of corroded reinforced concrete rectangular beams[J]. China Journal of Highway and Transport, 2009, 22(3): 45-51. (in Chinese))
[12] AZAD A K, AHMAD S, AZHER S A. Residual strength of corrosion-damaged reinforced concrete beams[J]. ACI Materials Journal, 2007, 104(1): 40- 47.
[13] NAAMAN A E, BURNS N, FRENCH C, et al. Stresses in unbonded prestressing tendons at ultimate: recommendation[J]. ACI Structural Journal, 2002, 99(4): 518-529.
[14] LONG X, TAN K H, LEE C K. Bond stress-slip prediction under pullout and dowel action in reinforced concrete joints[J]. ACI Structural Journal, 2014, 111(4): 977-987.
[15] EL-TAWIL S, OGUNC C, OKEIL A, et al. Static and fatigue analysis of RC beams strengthened with CFRP laminates[J]. Journal of Composites for Construction, 2001, 5(4): 258-267.
[16] COLLINS M, MITCHELL D. Prestessed concrete struture[M]. Englewood Cliffs, NJ: Prentice Hall, 1991.
[17] CAIRNS J, ABDULLAH R B. Bond strength of black and epoxy-coated reinforcement: a theoretical approach[J]. ACI Materials Journal, 1996, 93(4): 362-369.
[18] GIURIANI E, PLIZZARI G, SCHUMM C. Role of stirrups and residual tensile strength of cracked concrete on bond[J]. Journal of Structural Engineering, 1991, 117(1): 1-18.
[19] WANG X, LIU X. Modeling bond strength of corroded reinforcement without stirrups[J]. Cement and Concrete Research, 2004, 34(8): 1331-1339.
[20] American Concrete Institute. Building code requirements for structural concrete and commentary: ACI 318- 08[S]. Fsrmington Hills,MI: ACI, 2008.
[21] CEB-FIP. FIB model code for concrete structures: CEB-FIP: 2010[S]. Lausanne, Switzerland: fib, 2010.
[22] WANG L, MA Y, DING W, et al. Comparative study of flexural behavior of corroded beams with different types of steel bars[J]. Journal of Performance of Constructed Facilities, 2015, 29(6): 04014163.