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一、混凝土拉伸试验的软化性质及断裂能用图1(a)所示试件进行拉伸试验,如拉伸试验是由位移控制并且是稳定的,则其典型应力——伸长曲线如图1(b)所示,从该图应力——伸长曲线可以看出,在达到最大荷载前近似于一直线,超过最大荷载后立即下降,这种存在下降段的现象称之为软化性质,试验表明在破坏前某处将形成一断裂区,随着断裂区的损伤增加,变形将增加并导致应力减少,随着应力的减少,断裂区以外将卸载、断裂区不沿试件长度的方向扩展,而仅限于开始产生损伤的区域.
First, the softening and tensile energy of the concrete tensile test The tensile test is performed using the test piece shown in Figure 1(a). If the tensile test is controlled by the displacement and is stable, the typical stress-elongation curve is as follows: As shown in Fig. 1(b), from the stress-elongation curve of this figure, it can be seen that the line is approximately a straight line before reaching the maximum load and decreases immediately after the maximum load is exceeded. This phenomenon of existence of a descending segment is called a softening property. The test showed that a fracture zone will be formed somewhere before the failure. As the damage in the fracture zone increases, the deformation will increase and cause the stress to decrease. With the reduction of the stress, the fracture zone will be unloaded and the fracture zone will not follow the length of the test piece. The direction of expansion, but only to start the area of damage.