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本文对乱向短纤维增强混凝土在直接拉力作用下裂后的纤维有效系数,进行了探讨。根据埋深长度相同的纤维具有相等拔出力而与纤维取向无关的假设,并按照统计规则,作者得到纤维由于取向不同而引起的裂后增强效率为cosθ。然后应用概率理论求出合理的乱向短纤维方向有效系数C_0。根据上述假设,可以得出取向不同的纤维将具有相同的临界长度的结论。这样,也就可应用概率理论、推导纤维长度有效系数C_l。本文还提出了界面粘结系数C_b并说明了它的物理意义。最后,作者提出了下列分式:计算裂后纤维有效系数C_f的为 C_f=C_θC_bC_l;纤维临界体积率V_f(crit)的为 V_(f(crit))=(σ_(mu))/C_(fσfu)-_(η0∈_(mu)E_f+ηθσ_(mu);复合材料的极限直接抗拉强度或裂后抗拉应力为σ_(cu)=C_(fσfu)V_f。实验值与估计值颇相一致。
In this paper, the effective coefficient of the fissured short fiber reinforced concrete under direct tension is discussed. According to the assumption that the fiber with the same buried depth has the same pull-out force and is independent of fiber orientation, and according to statistical rules, the authors obtained the post-crack enhancement efficiency cos θ due to different orientation of fibers. Then, probability theory was applied to find a reasonable direction coefficient of short-fiber direction C_0. Based on the above assumptions, it can be concluded that fibers with different orientations will have the same critical length. In this way, the probability theory can be applied and the fiber length effective coefficient C_l can be derived. This paper also proposed the interface adhesion coefficient C_b and explained its physical meaning. Finally, the author proposes the following formula: Calculate the post-fission fiber effective coefficient C_f is C_f=C_θC_bC_l; The critical fiber volume rate V_f(crit) is V_(f(crit))=(σ_(mu))/C_(fσfu )-_(η0∈_(mu)E_f+ηθσ_(mu)); the ultimate tensile strength or post-crack tensile stress of the composite is σ_(cu)=C_(fσfu)V_f. The experimental and estimated values are quite similar. Consistent.