嵌入式复材筋加固混凝土桥面板工作性能研究

STUDY ON THE BEHAVIOUR OF CONCRETE BRIDGE DECK SLABS STRENGTHENED WITH NEAR SURFACE MOUNTED FIBER REINFORCED POLYMER BARS

为了研究表面嵌入式(Near Surface Mounted,简称"NSM")纤维复合筋(FRP筋)加固钢筋混凝土面板的工作性能,对该加固桥面板结构进行试验研究,并通过改变加固筋材类型和加固方式分析其对面板加固效果的影响。通过分析试验结果发现,嵌入式加固能有效提高桥面板承载力,减少面板板底开裂程度和挠度,增强面板刚度,但由于侧向约束刚度的作用筋材类型变化的影响较小。为了深入研究该加固桥面工作机理,对试验模型进行有限元模拟,数值模拟结果与试验结果对比吻合良好。此后采用该数值模型进行参数分析,深入研究混凝土强度、侧向刚度、跨高比、FRP筋弹性模量、加固率、配筋率等结构参数变化对加固桥面板承载性能的影响。参数研究结果表明:侧向刚度和配筋率增加能提高桥面板承载力,但加固效果减弱;桥面板承载力随混凝土强度、加固率和FRP筋弹性模量的增加而提高,但弹性模量变化对桥面承载力提高幅度较小;跨高比增加,桥面板承载力减小,但加固面板承载力提高幅度增长。试验研究和数值分析的结果表明,工程加固时应根据加固面板结构自身材料强度、约束刚度和配筋率选用合理的FRP筋类型和加固率,充分发挥加固材料的作用。

To study the behaviour of concrete bridge deck slabs strengthened with Near Surface Mounted（ NSM） Fiber Reinforced Polymer（ FRP） bars,an experimental test of this strengthened concrete deck slab was carried out. In this experimental test,the material of strengthening FRP and strengthening configuration were varied to investigate the influence of those structural parameters. It was found that the ultimate strengths of strengthened concrete deck slabs were enhanced significantly by using the NSM strengthening method. Interestingly,the variation of strengthening FRP bar materials had no strong effect on the behaviour of strengthened concrete deck slabs due to the lateral restraint stiffness. To develop further study of the behaviour of NSM strengthened concrete deck slabs,a finite element analysis（ FEA） of the test specimens was proposed. In the comparison of the results from numerical analysis and the test results,the FEA results showed good correlation with the test results. Thereafter,a series of parametric study was conducted with this numerical model,which included concrete strengths,lateral restraint stiffness,span-to-depth ratio,elastic modulus of FRP bars,strengthening percentage and reinforcement percentage. It was shown that increasing the lateral restraint stiffness and reinforcement percentage would result in higher loadingcarrying capacity but weakened the strengthening effect. In addition,the ultimate capacity of strengthened concrete deck slabs was enhanced by increasing the concrete strengths and elastic modulus of FRP bars. As expected,the ultimate strengths of concrete deck slabs were reduced by increasing the span-to-depth ratios. Based on the study of experimental and numerical results,it can be concluded that the material properties of FRP and strengthening percentages should be determined according to the concrete strength,lateral restraint stiffness and reinforcement ratio of deck slabs in the structural design.