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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 control the deflection of RC beams strengthened by prestressed CFRP plate more accurately and guide the reinforcement design of the project, the concept of “indirect stiffness” is put forward and its mechanism is tested. A total of six reinforced concrete test beams were tested indoors, including three prestressed CFRP plates (one with a loading test beam), one reinforced CFRP plate and two unbonded beams. The comparative analysis The influence of different reinforcement methods on the bearing capacity and stiffness of the beam was deduced. Based on the analysis of the cross-section of the whole test beam during the stress phase, the formula for calculating the indirect stiffness of the strengthened beam with prestressed CFRP sheets was deduced and compared with the finite element analysis . The results show that the load-bearing capacity of CFRP board is about 40% higher than that of the un-strengthened beam. After the CFRP board is prestressed, the beam will reverse arch under the action of axial prestress. Compared with the CFRP board The yield stress of the reinforced beam is only increased by 8.3%, but its mid-span deflection and cross-section curvature are reduced by 31.8% and 54.5% respectively, which shows that the prestressed CFRP plate reinforcement technology can effectively improve the deformation capacity of the beam. , The form is simple, combined with the current norms is better, and the calculated value is in good agreement with the test value, which is suitable for the reinforced beam with loading history.