低预应力CFRP板加固RC梁模型试验研究

Experimental Study on RC Beam Model Reinforced with Low Prestressed CFRP Plates

为研究低预应力CFRP加固RC梁的力学性能,设计进行了CFRP加固方法的对比模型梁试验。通过对直接粘贴、机械张拉粘贴锚固成为低应力CFRP板及粘贴加热伸长后回缩成为低预应力CFRP板这3种方法,将同规格的CFRP板粘贴在混凝土试验梁表面,通过分级加载试验,获得不同施工方法的CFRP板加固后开裂荷载、极限荷载、裂缝发展及荷载-挠度曲线等。试验结果表明:3种施工方法下进行机械张拉低预应力CFRP板加固对原梁抗剪承载力性能提高较大。在正常使用阶段,机械张拉低预应力CFRP板加固梁和加热张拉低预应力CFRP板加固梁出现斜裂缝的荷载等级高于直接粘贴CFRP加固梁出现斜裂缝的荷载等级。机械张拉低预应力CFRP板加固梁和加热张拉低预应力CFRP板加固梁产生的裂缝宽度小于直接粘贴CFRP板加固梁产生的裂缝宽度。相对最明显的是机械张拉低预应力CFRP板,裂缝一直维持在较低水平。粘贴锚固的低预应力CFRP加固方式操作相对简单,可应用于桥梁维修或拆除前临时加固工程等。

In order to study the mechanical properties of RC beams strengthened with low prestressed CFRP,a comparative model beam test of CFRP reinforcement method was designed and carried out.Through the three methods of direct bonding,mechanical tension bonding and anchoring to become low-stress CFRP plate and bond heating and stretching to retract to become low-prestressed CFRP plate,the CFRP plate of the same specification is bonded to the surface of the concrete test beam.Through the graded loading test,the cracking load,ultimate load,crack development and load-deflection curve of CFRP plate reinforced by different construction methods are obtained.The test results show that the shear bearing capacity of the original beam is greatly improved by mechanical tension of low prestressed CFRP plate under three construction methods.In the normal use stage,the load level of diagonal cracks in the beam strengthened by mechanical tensioned low prestressed CFRP plate and the beam strengthened by heating tensioned low prestressed CFRP plate is higher than that of the beam strengthened by directly bonded CFRP.The crack width of mechanical tensioned low prestressed CFRP plate reinforced beam and heated tensioned low prestressed CFRP plate reinforced beam is smaller than that of directly bonded CFRP plate reinforced beam.The most obvious is the mechanical tension of low prestressed CFRP plate,cracks have been maintained at a low level.Bonded low prestressed CFRP reinforcement method is relatively simple,can be applied to bridge maintenance or temporary reinforcement works before demolition.