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一、应力重分布的概念在墩台结构的应力计算中,根据规定,只考虑圬工的抗压强度,不考虑圬工的抗拉强度。因此,在偏心压缩下,当合外力作用在截面核心之外时(截面核心是指截面形心附近的这样一个范围,当荷重作用到这范围之内或边界时,中性轴就在截面之外或与截面周边相切,而使截面只产生压应力,这个范围称之为“截面核心”。有关内容在Ⅰ—三中详细说明)。假定圬工截面上将发生裂缝,全部压力仅由不受拉力部分的截面承受,此时须将应力重新分布,求出承受全部压力部分的截面最大压应力。应力重分布后的最大压应力是从下列基本条件出发进行计算的(图1):
First, the concept of stress redistribution In the calculation of the stress of abutment structures, according to the regulations, only the compressive strength of the completion is considered and the tensile strength of the completion is not considered. Therefore, under eccentric compression, when the external force acts on the core of the cross-section (cross-section core refers to such a range near the cross-sectional centroid, when the load is applied to this range or boundary, the neutral axis is in the cross-section. Outside or tangent to the cross-section perimeter, and the cross-section only produces compressive stress, this range is called “cross-section core.” Details are described in I - III). Assuming that cracks will occur in the section of the concrete construction, all pressures will only be absorbed by the sections that are not subject to tension. In this case, the stress must be redistributed to obtain the maximum compressive stress of the section that receives all the pressure. The maximum compressive stress after stress redistribution is calculated from the following basic conditions (Figure 1):