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本文提出采用材料力学的公式,作为预应力混凝土、钢筋混凝土及混凝土构件抗裂性的通用计算法,但截面边缘假想弯曲抗拉强度R_(pu)与轴心抗拉强度R_p之比r=W_n/W_o=R_(pu)/R_p及受拉钢筋化为混凝土截面之折算系数n_p,则在作者以往工作的基础上,考虑混凝土受拉区的弹塑性及钢筋附加抗裂能力,从理论及试验方面给予论证。给出具有普遍意义的工字形、T形(П形)、?形(?形)、矩形截面的r值计算公式和相应的反映截面高度对r值影响的参数α以及钢筋折算系数n_p之值。 用截面高度为10～100厘米,配筋率μ_1=0～3.38％、截面形状为矩形、T形及?形的混凝土梁、钢筋混凝土梁及预应力混凝土梁,以及偏心距e_T/h=0.266～0.43、μ_1=0.227～0.752％、b×h=10×20～80×160厘米的钢筋混凝土偏心受压构件的试验资料,对本文建议的方法及给出的参数作了校核。计算表明,所建议的方法和计算参数是足够简便可靠,并具有较广泛的适用性,可以作为研究各种工程结构领域中预应力混凝土、钢筋混凝土和混凝土构件抗裂性计算的通用方法的参考。 附录列有矩形、工字形(箱形)、T形(П形)及?形(?形)截面的r值计算图。
This paper proposes the formula of material mechanics as a general calculation method for the crack resistance of prestressed concrete, reinforced concrete and concrete components, but the ratio of the imaginary bending tensile strength R_(pu) of the cross-section edge to the tensile strength R_p of the axial center r=W_n /W_o=R_(pu)/R_p and the coefficient of reduction n_p of the concrete section subjected to tensile reinforcement are based on the previous work of the author, taking into account the elasto-plasticity of the concrete tension zone and the additional anti-cracking capability of the steel bar, from theory and test. The argument is given. The formulas for calculating the r-values of I-shape, T-shape, ?-shape, and rectangular cross-section with universal significance are given and the corresponding parameters α and the value of n_p that reflect the influence of section height on r-value are given. . With a section height of 10 to 100 cm, reinforcement ratio μ_1 = 0 to 3.38%, cross-sectional shapes of rectangular, T-shaped and concrete-shaped concrete beams, reinforced concrete beams and prestressed concrete beams, and eccentricity e_T/h=0.266 The experimental data of ~0.43, μ_1 = 0.227 ~ 0.752%, and b × h = 10 × 20 ~ 80 × 160 cm reinforced concrete eccentric compressive members were checked and the proposed method and the parameters given were verified. The calculations show that the proposed method and calculation parameters are sufficiently simple and reliable, and have wide applicability, and can be used as a reference for studying the general method for calculating the crack resistance of prestressed concrete, reinforced concrete and concrete components in the field of various engineering structures. . The appendix lists the calculations of r values for rectangular, I-shaped (box), T-shaped (П), and ?-shaped (?-shaped) sections.