预应力CFRP板加固钢筋混凝土梁间接刚度试验

Experiment on Indirect Stiffness of RC Beams Strengthened with Prestressed CFRP Plate

为了较准确控制预应力CFRP板加固RC梁的挠度,以指导工程加固设计,提出了"间接刚度"的概念,并对其机理进行了试验研究。在室内共进行了6根钢筋混凝土试验梁静载试验,包括3根预应力CFRP板加固梁(其中1根有加载历史的试验梁),1根粘贴CFRP板加固梁,2根未加固梁;对比分析了不同加固方式对梁承载能力及刚度的影响;在对试验梁全过程受力阶段截面分析的基础上,推导出了预应力CFRP板加固梁间接刚度的计算公式,并进行了有限元对比分析。结果表明:相对于未加固梁,预应力CFRP板加固梁的承载能力提高了40%左右;使用预应力CFRP板加固后,梁在轴向预应力作用下会产生反拱,相对于粘贴CFRP板加固梁,其屈服荷载仅提高了8.3%,但其跨中挠度和截面曲率分别下降了31.8%和54.5%,说明使用预应力CFRP板加固技术可有效改善梁的变形能力;提出的公式概念明确,形式简便,与现行规范结合较好,且计算值与试验值吻合较好,适用于有加载历史的加固梁。

In order to accurately control the deflection of RC beams strengthened with prestressed CFRP plate so as to guide the engineering reinforcement design, the concept of indirect stiffness was put forward, and its mechanism was investigated by experiments. 6 RC beams were tested in the laboratory under static load, 3 of which were strengthened with prestressed CFRP plates （1 beam with loaded history）, 1 pasted with CFRP plate and 2 beams without reinforcement. The influences of different reinforcement methods on the carrying capacity and bending stiffness of beams were compared and analyzed; based on the section mechanical analysis of tested beam in the whole process of loading stage, the indirect stiffness calculation formula for the beam strengthened with prestressed CFRP plate was derived, and the finite element analysis was carried out to compare with it. The results show that the carrying capacity of beams strengthened with prestressed CFRP plate is increased by about 40% comparing with that of unreinforced beam; under the action of axial prestress, the beams strengthened with prestressed CFRP plate will produce antiarch. Compared with the bonded CFRP plate reinforced beams, its yield load is only increased by 8. 3%, while mid-span deflection and sectional curvature are decreased by 31.8% and 54. 5% respectively, which indicates that the deformation of the beam can be improved effectively by using the prestress reinforcement technique of CFRP plate; the proposed formula is clear in concept, simple in form, better in combination with the current standards, and the calculated values of the formula are in good agreement with the experimental values, which is suitable for the reinforced beams with loading history.