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首页> 外文会议>Sustainable Performance of Concrete Bridges and Elements Subjected to Aggressive Environments: Monitoring, Evaluation amp; Rehabilitation >Finite Element Modeling of RC Beams Strengthened with Prestressed NSM-CFRP Strips Subjected to Severe Environmental Conditions
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Finite Element Modeling of RC Beams Strengthened with Prestressed NSM-CFRP Strips Subjected to Severe Environmental Conditions

机译：恶劣环境条件下用预应力NSM-CFRP条加固的RC梁的有限元建模

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摘要

A nonlinear 3D Finite Element (FE) analysis was performed to predict the post-exposure load-deflection responses of Reinforced Concrete (RC) beams strengthened in flexure using prestressed Near-Surface Mounted (NSM) Carbon Fibre Reinforced Polymer (CFRP) strips. Five RC beams (5.15 m [16.90 ft] long) were modeled including one un-strengthened control beam and four beams strengthened using NSM-CFRP strips prestressed to 0, 20, 40, and 60% of the ultimate CFRP tensile strain. The beams were severely deteriorated due to applying accelerated environmental conditions consisting of 500 freeze-thaw cycles: three cycles per day between +34℃ [93℉] to -34℃ [-29℉] with fresh water spray for 10 minutes at a rate of 18 L/min [4.8 gallon/min] at temperature +20℃. The accelerated environmental conditions used in this study equivalent to 0.46 year of exposure inside a chamber, corresponds to a minimum lifetime of 12.8 years in Canada. Simultaneously, each beam was subjected to a sustained load equal to 62 kN [13.9 kip] representing 47% of analytical ultimate load of the non-prestressed NSM-CFRP strengthened RC beam. The degradation which occurred in the concrete properties, concrete-epoxy interface, and steel reinforcement was considered in the FE model. Also, debonding at the concrete-epoxy interface was simulated by assigning shear and normal fracture energies and the prestressing was applied to the CFRP strip using an equivalent temperature. The FE model was validated with the experimental test results. However, the experimental and numerical load-deflection curves were comparable up to yielding but after yielding, the predicted curves were not in good agreement with the experimental ones.
机译：进行了非线性3D有限元（FE）分析，以预测使用预应力近表面安装（NSM）碳纤维增强聚合物（CFRP）条增强了抗弯强度的钢筋混凝土（RC）梁的暴露后荷载-挠度响应。建模了五根RC梁（5.15 m [16.90 ft]长），包括一根未加强的控制梁和四根使用NSM-CFRP条加固的梁，这些梁预应力至极限CFRP拉伸应变的0％，20％，40％和60％。由于应用了加速的环境条件（包括500次冻融循环），光束严重恶化：每天在+ 34℃[93℉]至-34℃[-29℉]之间进行三个循环，并以一定速率喷洒淡水10分钟在温度+20℃时为18 L / min [4.8加仑/ min]。在这项研究中使用的加速环境条件相当于在室内暴露0.46年，相当于加拿大的最低寿命为12.8年。同时，每个梁承受的持续载荷等于62 kN [13.9 kip]，占非预应力NSM-CFRP增强RC梁的分析极限载荷的47％。在有限元模型中考虑了在混凝土性能，混凝土-环氧树脂界面和钢筋中发生的降解。同样，通过分配剪切力和正常断裂能来模拟混凝土-环氧树脂界面处的脱胶，并使用等效温度将预应力施加到CFRP板上。 FE模型已通过实验测试结果进行了验证。然而，试验屈服曲线和数值载荷挠度曲线在屈服之前是可比的，但屈服后，预测曲线与实验曲线并不完全一致。

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