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为模拟实际工程中加固构件的真实承载能力,实验在原混凝土构件持续受荷状态下,采用自密实混凝土对构件进行加固、养护。共进行了7根二次受力下自密实混凝土加固钢筋混凝土梁和2根对比梁的受弯性能试验,研究了不同初始受力水平、不同加固厚度及不同界面处理方式对加固钢筋混凝土梁抗弯承载力和截面刚度的影响。试验量测了构件裂缝分布形态、荷载-挠度曲线、钢筋应变发展规律等。结果表明:采用自密实混凝土加固钢筋混凝土梁,能有效地提高钢筋混凝土梁的抗弯承载力、截面刚度等性能;二次受力下自密实混凝土加固梁抗弯承载力随着初始受力水平的增大而降低。在试验结果的基础上,基于平截面假定,提出了二次受力下自密实混凝土加固梁钢筋滞后应变及抗弯承载力计算式,计算结果与试验结果吻合良好。
In order to simulate the real carrying capacity of the reinforced members in the actual project, the self-compacting concrete was used to reinforce and maintain the members under the condition that the original concrete members were continuously loaded. A total of seven flexural tests of seven reinforced concrete beams strengthened with self-compacting concrete under two secondary forces and two comparative beams were carried out. The flexural bearing capacity of reinforced concrete beams with different initial stress level, different thickness of reinforcement and different interface treatments were studied. Influence of force and section stiffness. The crack distribution pattern, load-deflection curve and the law of steel bar strain development were measured. The results show that using self-compacting concrete to reinforce reinforced concrete beams can effectively improve the flexural capacity and cross-section stiffness of reinforced concrete beams. The flexural capacity of self-compacting concrete beams under secondary load increases with the increase of initial load level Big and lower. Based on the experimental results, based on the assumption of flat section, the calculation formula of the hysteresis strain and the flexural capacity of reinforced concrete beams strengthened with self-compacting concrete under the secondary loading is proposed. The calculation results are in good agreement with the experimental results.