碳纤维增强复合网格-聚合物水泥砂浆加固RC梁抗剪性能试验研究

Experimental study on shear performance of RC beams strengthened with CFRP grid-PCM

为研究碳纤维增强复合(CFRP)网格和聚合物水泥砂浆(PCM)复合加固工字形截面钢筋混凝土(RC)梁的抗剪性能,对3个试件进行抗剪性能试验和有限元模拟,分析了CFRP网格-PCM加固RC梁的抗剪破坏机理,研究了不同加固方式对试件抗剪性能的影响。研究结果表明:采用CFRP网格-PCM对RC梁进行抗剪加固可有效抑制斜裂缝的发展,能够较大幅度提高RC梁的抗剪承载力;相比仅腹部加固的试件,腹部和腋部都加固的试件的二次刚度、极限荷载均有所提高,且CFRP网格变形减小,与混凝土界面的黏结能力增强;在有限元分析中,采用混凝土的CDP模型和Spring2弹簧单元来预测CFRP网格加固混凝土的抗剪承载力是可行的;建立了基于杆状材料有效应变的抗剪计算方法,该方法可有效预测加固RC梁的抗剪承载力,为结构加固设计提供参考。

To investigate the shear performance of reinforced concrete( RC) beams strengthened with carbon fiber reinforced polymer( CFRP) grid and polymer cement mortar( PCM),two-point loading tests and finite element analysis( FEA) for three specimens were carried out. The main test variable was the strengthening scheme,whose effects on the failure mechanism and the shear performance of the strengthened RC beams were analyzed. The results show that the development of inclined cracks is effectively restrained by using CFRP grid-PCM for RC beams,and the shear capacity can be significantly improved to a certain extent. Compared to the specimen strengthened at the web only,the secondary stiffness and the ultimate load of the beam strengthened at both the web and the hunch are both increased to some extent. In addition,for the latter,the deformation of CFRP grid is reduced,and the bonding behavior on the interface between the composite layer and concrete substrates is improved. For FEA,it is feasible to predict the shear capacity of RC beams strengthened by CFRP grid using both concrete damaged plastic( CDP) and Spring2 models. Based on the effective strain of FRP rod,a new calculation method is developed to predict the shear capacity validly and the method can be also considered as a reference for the design of reinforced structures.