胡少伟, 尹阳阳, 范冰, 张润. 基于等效纯弯曲梁的混凝土双K断裂参数研究[J]. 工程力学, 2019, 36(12): 44-51. DOI: 10.6052/j.issn.1000-4750.2018.12.0718
引用本文: 胡少伟, 尹阳阳, 范冰, 张润. 基于等效纯弯曲梁的混凝土双K断裂参数研究[J]. 工程力学, 2019, 36(12): 44-51. DOI: 10.6052/j.issn.1000-4750.2018.12.0718
HU Shao-wei, YIN Yang-yang, FAN Bing, ZHANG Run. STUDY OF THE DOUBIE-K FRACTURE PARAMETERS OF CONCRETE BASED ON EQUIVALENT PURE BENDING BEAMS[J]. Engineering Mechanics, 2019, 36(12): 44-51. DOI: 10.6052/j.issn.1000-4750.2018.12.0718
Citation: HU Shao-wei, YIN Yang-yang, FAN Bing, ZHANG Run. STUDY OF THE DOUBIE-K FRACTURE PARAMETERS OF CONCRETE BASED ON EQUIVALENT PURE BENDING BEAMS[J]. Engineering Mechanics, 2019, 36(12): 44-51. DOI: 10.6052/j.issn.1000-4750.2018.12.0718

基于等效纯弯曲梁的混凝土双K断裂参数研究

STUDY OF THE DOUBIE-K FRACTURE PARAMETERS OF CONCRETE BASED ON EQUIVALENT PURE BENDING BEAMS

  • 摘要: 因四点弯曲梁跨中裂缝截面附近处于纯弯段,故其从理论上更符合Ι型断裂模式。基于此,该文通过开展跨中带缝的四点弯曲梁试验,将荷载作用下的四点弯曲梁纯弯曲段等效为纯弯曲梁,基于线性叠加原理给出了计算混凝土四点弯曲梁双K断裂参数的计算公式,并研究了不同初始缝高比(0.2、0.3、0.4、0.5及0.6)对四点弯曲梁双K断裂参数的影响,结果表明:随着初始缝高比的增大,试件起裂荷载Pini,最大荷载Pmax及相对临界有效裂缝扩展长度(ac-a0)/H均逐渐减小;起裂断裂韧度KICini和失稳断裂韧度KICun基本保持不变。可见,四点弯曲梁可以用于研究混凝土的双K断裂参数。

     

    Abstract: In a four-point bending (FPB) test, the beam segment near the mid-span cracking section is under pure bending. Therefore, the mode Ι fracture model can be better applied in theory. Based on this, FPB tests on notched beams were carried out. The calculation formulae of double-K fracture parameters were established by assuming that the pure bending segment of a FPB specimen under external load is equivalent to a pure bending specimen and by using the linear superposition principle. Moreover, the effect of different initial crack-depth ratios (0.2, 0.3, 0.4, 0.5 and 0.6) on the fracture parameters was evaluated. The results indicate that with the increase of the initial crack-depth ratio, the initial fracture load, Pini, the maximum fracture load, Pmax and the critical relative effective crack propagation length, (ac-a0)/H, decrease gradually while the initial fracture toughness, KICini and the unstable fracture toughness, KICun keep almost constant. Consequently, FPB tests can be applied to determine the double-K fracture parameters of concrete.

     

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