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FRP(fiber reinforced polymer)片材增强钢筋混凝土梁纵筋屈服前刚度是其正常使用阶段的刚度,而纵筋屈服后刚度(又称二次刚度)则能够控制超载情况下梁的变形,因此,两个阶段的刚度都很重要。本文对FRP增强钢筋混凝土梁在受拉纵筋屈服前和屈服后两个阶段的刚度进行了理论分析,将纵筋屈服前后截面弯矩表达为受拉纵筋和FRP应变的函数,推导了增强材料应变不均匀系数的计算式,通过全过程分析得到了受压区混凝土边缘平均应变综合系数随截面弯矩的变化规律,发现屈服后阶段的变化规律明显不同于普通钢筋混凝土梁;通过对80根试验梁数据和40根模拟梁的全过程分析数据进行回归,得到了FRP增强钢筋混凝土梁的刚度和挠度计算式;将计算值与本文试验的实测值以及全过程分析结果进行对比,最后用文献中的试验数据进行了验证。结果表明,本文提出的刚度和挠度计算式具有较高的精度。
The pre-yield stiffness of FRP (reinforced concrete) sheet reinforcement is the normal stiffness of its longitudinal reinforcement. The post-yield stiffness (or quadratic stiffness) of the longitudinal reinforcement can control the deformation of the beam under overload. Therefore, The stiffness of both phases is important. In this paper, the stiffness of FRP-reinforced concrete beams before and after yielding are analyzed theoretically. The moments before and after yielding are expressed as a function of tensioning force and FRP strain, Through the whole process of analysis, the law of the average strain of the concrete in the compression zone varies with the bending moment of the section, and the variation law of the post-yielding stage is obviously different from that of ordinary reinforced concrete beam. Root test beam data and 40 simulated beam whole process analysis data are regressed to obtain the FRP reinforced concrete beam stiffness and deflection formula; the calculated value and the experimental results of this paper and the whole process of the analysis results are compared, and finally with The experimental data in the literature were validated. The results show that the stiffness and deflection formulas proposed in this paper have higher accuracy.