截面贯入式FRP筋加固混凝土桥面板抗剪性能试验研究

EXPERIMENTAL STUDY ON SHEAR PERFORMANCE OF EMBEDDED THROUGH SECTION SHEAR STRENGTHENING OF CONCRETE BRIDGE SLABS

现有桥梁交通量增加、重型卡车靠边跨行驶使得传统混凝土桥面板易发生支座附近区域抗剪破坏,而现有加固方式多针对构件抗弯加固而忽视抗剪问题。本文根据实际桥面板受力状况,采用截面贯入式加固(Embedded Through Section,简称"ETS")方法并结合纤维增强复合材料(Fiber Reinforced Polymer,简称"FRP")筋对桥面板进行抗剪加固,对比加固筋的筋材类型、筋材直径以及钻孔损伤的影响。通过分析试件承载力、裂缝分布、破坏模式发现:该加固方法能有效提高桥面板板带抗剪承载力,构件破坏模式从脆性的剪切破坏转变为延性的弯曲破坏或弯剪复合破坏;钻孔损伤和筋材类型变化对桥面板受力与变形影响较小,并且采用FRP材料更能提高加固后结构的耐久性。最后,针对此加固方法提出了相应的承载力计算公式,计算结果与试件承载力吻合良好。

The increase in traffic and heavy trucks loads close to supports have caused shear failure of concrete bridge decks.However,the existing strengthening methods commonly focus on the improvement of bending capacity of concrete bridge decks while ignoring the situation of shear failure problems.This paper reveals a comprehensive study of the behaviour of concrete slabs shear strengthened with Embedded Through Section(ETS)technique with fibre reinforced polymer(FRP)bars.Several structural variables like material type,diameter,and drilling damage were varied to assess the effectiveness of this shear strengthening technique.By analyzing the bearing capacity,crack distribution and failure mode of the test specimen,the results show that the strengthening method can effectively improve the shear capacity of concrete bridge slabs,and the failure mode changes from brittle shear failure to ductile bending failure or bending-shear composite failure.The drilling holes and different type of strengthening bars have little effect on the capacity and deformation of the bridge decks.Additionally,the use of FRP material can improve the durability of the bridge decks.Finally,a two-way theoretical model was proposed to predict the loading-carrying capacity of concrete slabs strengthened with ETS FRP bars.The ultimate strength predicted by this theoretical method shows good agreement with the test results.