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为研究缝高比对钢筋混凝土起裂韧度、失稳韧度等断裂参数的影响,以及钢筋在混凝土裂缝扩张过程中对裂缝的限制作用,设计制作了4组初始缝高比分别为0.2、0.3、0.4、0.5的标准钢筋混凝土三点弯曲梁,对其进行了断裂性能试验研究。根据试验现象分析了裂缝扩展过程,在此基础上建立了断裂韧度计算模型,给出了考虑钢筋限裂作用后的有效裂缝长度计算式。研究结果表明:在引入适应于钢筋混凝土的断裂韧度后,其裂缝扩展过程也可以用双K断裂准则来描述;当试件的初始缝高比大于或等于0.4时,钢筋混凝土三点弯曲梁的起裂断裂韧度和失稳断裂韧度与初始缝高比无关;声发射参量可以准确地确定试件的起裂荷载值,而且与传统的应变片法相比,声发射信号能更好地反映试件内部真实的起裂状态。
In order to study the influence of the ratio of the seam height to the fracture parameters such as the fracture toughness and the instability toughness of the reinforced concrete and the limiting effect of the reinforcement on the crack during the crack propagation of the concrete, four initial seam height ratios of 0.2, 0.3,0.4,0.5 standard reinforced concrete three-point bending beam, its fracture performance test. Based on the experimental phenomena, the crack propagation process is analyzed. Based on the analysis, the fracture toughness calculation model is established and the effective fracture length formula is given after considering the crack initiation. The results show that the crack growth process can be described by the double-K fracture criterion when the fracture toughness is introduced into the reinforced concrete. When the initial fracture height ratio is greater than or equal to 0.4, the three-point bending beam The initiation fracture toughness and the failure fracture toughness have no relation with the initial seam height ratio. The acoustic emission parameters can accurately determine the initiation and breaking load values of the specimens. Compared with the traditional strain gage method, the acoustic emission signals can be better Reflect the real state of initiation within the specimen state.