荷载与湿热环境耦合作用下粘钢加固RC梁的耐久性能
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摘要
粘贴钢板在钢筋混凝土结构加固领域得到了广泛的关注,但关于加固结构耐久性的研究较少涉及,尤其是荷载与湿热环境耦合作用下的耐久性研究。为探究粘钢加固RC梁在湿热环境与荷载耦合作用下的耐久性与损伤机理,开展了空载、静载和交变荷载与湿热环境耦合作用下7片粘贴钢板加固钢筋混凝土梁的15、30 d高温高湿老化试验,最后进行了加固梁的三点弯曲试验,获取了不同荷载与环境工况耦合作用下加固梁的破坏形态、挠度、钢板与钢筋应变等力学参数,进一步分析了荷载与湿热环境耦合作用对加固RC梁的力学性能及耐久性能的影响。结果表明:经过15、30 d的湿热老化后,粘贴钢板加固RC梁的力学性能有所退化,耦合静载作用的加固梁力学性能退化更加明显,耦合交变荷载作用的加固梁力学性能退化最为显著;交变荷载与湿热环境作用下加固梁的极限强度、弯曲性能、钢板极限应变较对比梁分别下降17.26%、17.21%、41.92%;荷载与湿热环境耦合作用对梁体受力性能影响较大,对破坏模式影响较小,加固梁在荷载与湿热环境耦合作用下的破坏模式分为混凝土开裂、裂缝发展、钢板剥离破坏3个阶段;湿热腐蚀介质渗透入钢筋混凝土梁及粘结界面,对加固结构耐久性造成了损伤,荷载耦合作用进一步加剧了损伤演化。
Bonded steel plate has attracted extensive attention in the field of reinforced concrete structure, but the durability study of reinforced structure is rarely involved, especially the durability study of the coupling action of load and hydrothermal environment. In order to explore the durability and damage mechanism of reinforced concrete beams strengthened with bonded steel plates under the coupling action of load and hydrothermal environment, a steel plate bonded concrete reinforced with 7 bonded steel plates r was tested under hydrothermal environment. Considering the coupling action of no-load, static load and alternating load with hydrothermal environment respectively, the aging test was conducted in 15 days and 30 days under high temperature and humidity conditions. Finally, the mechanical test was performed to obtain failure mode, deflection, strain of steel plate and steel bar under the coupling action of different load and environment. After long term load and hydrothermal environment coupling, the mechanical properties of the reinforced structure was studied, as well as the damage of durability. Results showed that the mechanical properties of the reinforced beams with no load action were degraded after 15 days and 30 days. And the strengthened beams under the static load were more obvious. Especially for reinforced beams under the action of alternating load, the mechanical properties of the beams were most significantly degraded. Alternating load and hydrothermal action made the mechanical performance of reinforced beams decrease and the ultimate strength, flexural behavior and ultimate strain of steel plate were decreased by 17.26%, 17.21% and 41.92%, respectively, compared with the reference beam. The coupling of load and hydrothermal environment had an effect on the stress in beams, while did not have any significant effect on failure pattern. And the failure modes of reinforced beams under the coupling action of load and hydrothermal environment were divided into three stages of concrete cracking, crack development and steel plate peeling failure. The penetration of hydrothermal corrosion medium into reinforced concrete beams and bonding interface caused damage to durability and this effect was aggravated under the action of load.
Bonded steel plate has attracted extensive attention in the field of reinforced concrete structure, but the durability study of reinforced structure is rarely involved, especially the durability study of the coupling action of load and hydrothermal environment. In order to explore the durability and damage mechanism of reinforced concrete beams strengthened with bonded steel plates under the coupling action of load and hydrothermal environment, a steel plate bonded concrete reinforced with 7 bonded steel plates r was tested under hydrothermal environment. Considering the coupling action of no-load, static load and alternating load with hydrothermal environment respectively, the aging test was conducted in 15 days and 30 days under high temperature and humidity conditions. Finally, the mechanical test was performed to obtain failure mode, deflection, strain of steel plate and steel bar under the coupling action of different load and environment. After long term load and hydrothermal environment coupling, the mechanical properties of the reinforced structure was studied, as well as the damage of durability. Results showed that the mechanical properties of the reinforced beams with no load action were degraded after 15 days and 30 days. And the strengthened beams under the static load were more obvious. Especially for reinforced beams under the action of alternating load, the mechanical properties of the beams were most significantly degraded. Alternating load and hydrothermal action made the mechanical performance of reinforced beams decrease and the ultimate strength, flexural behavior and ultimate strain of steel plate were decreased by 17.26%, 17.21% and 41.92%, respectively, compared with the reference beam. The coupling of load and hydrothermal environment had an effect on the stress in beams, while did not have any significant effect on failure pattern. And the failure modes of reinforced beams under the coupling action of load and hydrothermal environment were divided into three stages of concrete cracking, crack development and steel plate peeling failure. The penetration of hydrothermal corrosion medium into reinforced concrete beams and bonding interface caused damage to durability and this effect was aggravated under the action of load.
引文
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[2]Zhang Hui,Yang Jianhong,Li Haibin,et al.Effects of hydrothermal aging on properties of epoxy resin[J].Ordnance Material Science&Engineering,2010,33(3):41-43.[张晖,阳建红,李海斌,等.湿热老化环境对环氧树脂性能影响研究[J].兵器材料科学与工程,2010,33(3):41-43.]
[3]Wei R,Sneed L H,Gai Y,et al.Test results and nonlinear analysis of RC T-beams strengthened by bonded steel plates[J].International Journal of Concrete Structures&Materials,2015,9(2):133-143.
[4]Bao Anhong.The study for the desquamation of affixed reinforced RC beam[D].Chongqing:Chongqing University,2005.[鲍安红.粘贴加固混凝土梁的剥离研究[D].重庆:重庆大学,2005.]
[5]Thamrin R,Sari R P.Flexural capacity of strengthened reinforced concrete beams with web bonded steel plates[C]//Proceedings of 2016 International Conference on Sustainable Civil Engineering Structures and Construction Materials.Langford Lane:Elsevier Ltd,.2016:1129-1136.
[6]Wang D G,Wang Z X,Xu B.Numerical investigation on shear failure of concrete beam strengthened by bonded steel plate[J].Applied Mechanics&Materials,2013,351/352:1552-1557.
[7]Lu Yiyan,Hu Ling,LiShan,et al.Experimental study and analysis on fatigue stiffness of RC beams strengthened with CFRP and steel plate[J].Journal of Central South University,2016,23(3):701-707.
[8]Huang Peiyan,Zhang Bolin,Yang Yi,et al.Effect of environmental temperature on load-carrying capacity of RC beam strengthened with CFL[J].Journal of South China University of Technology,2007,35(2):1-5.[黄培彦,张伯林,杨怡,等.环境温度对CFL增强RC梁承载能力的影响[J].华南理工大学学报(自然科学版),2007,35(2):1-5.]
[9]Shrestha J,Ueda T,Zhang D.Durability of FRP concrete bonds and its constituent properties under the influence of moisture conditions[J].Journal of Materials in Civil Engineering,2015,27(2):A4014009.
[10]Ren Huitao,Li Shan,Huang Chengkui.Study on durability of CFRP subjected to freeze-thaw cycle combined with sustained load[J].Engineering Mechanical,2010,27(4):202-207.[任慧韬,李杉,黄承逵.冻融循环和荷载耦合作用下CFRP(碳纤维增强聚合物)片材的耐久性试验研究[J].工程力学,2010,27(4):202-207.]
[11]Li Shan.Durability of concrete strengthened with FRP under environmental and loading conditions[D].Dalian:Dalian University of Technology,2009.[李杉.环境与荷载共同作用下FRP加固混凝土耐久性[D].大连:大连理工大学,2009.]