混凝土拉伸软化曲线折线近似的逆解方法

研究基于Hillerborg的虚拟裂纹模型，利用有限元分析方法，求得折线近似的拉伸软化曲线的逆解方法。对弹性模量，初始开裂应力的决定方法进行了研究。以双直线模型的计算结果为算例进行了逆推分析，算例符合得很好。也较好地从实验得到的荷载位移曲线再现了拉伸软化曲线。这对于研究混凝土的断裂能，尺寸效应等问题很具意义。

INVERSE METHOD FOR PIECEWISE LINEAR APPROXI MATION OF CONCRETE TENSION SOFTENING CURVE BASED ON FCM

The forming and growth of cracks in concrete structure causes destruction. It will cause a tension Softening phenomenon as a crack propagates, as there is a fracture process zone around the crack tip therefore, when we investigate destruction mechanism of concrete, we must consider tension softening curve pattern (like fracture energy) tension softening curve patterns) as an important material property. This property contains a lot of information to be used for explanation of concrete fracture phenomenon, e.g. constitutive equations for the analysis if crack growth, critera for the investigation of scale of micro-crack zone quantitatively) statement of brittleness mechanism, size effect and destruction model of high strength concrete. Because the tension softening property is as important as the ultimate strength is of importance to obtain the ultimate load and solve the buckling problem of concrete structure. It is especially difficult to obtain a stable tension softening curve for direct tensile test with concrete specimen. So a method is proposed to obtain tension softening curve indirectly through stable fracture toughness experiment by some scholars. In this paper, Some formulae about complete load-displacement curve are proposed. The effect is studied on the complete load-displacement curve due to different mesh subdivision, tension softening model and precast crack length. Further, a inverse method based on piecewise linear approximation is proposed. As for elastic modulus, a method for the determination of initial cracking stress is studied. Inverse analysis is made based on bilinear model and the load-displacement curve attained from experiment reshows the tension softening curve. It is important to study the fracture energy and size effect.