一个针对轻骨料混凝土的四参数多轴强度准则

A FOURPARAMETER MULTIAXIAL STRENGTH CRITERION FOR LIGHTWEIGHT AGGREGATE(LWA)CONCRETE

通过对轻骨料混凝土多轴应力状态下的破坏特征分析,发现轻骨料混凝土的空间破坏面与静水应力轴有两个交点,这与普通混凝土破坏面为开口的结论是截然不同的,因此那些针对普通混凝土建立起来的强度准则直接应用于轻骨料混凝土是行不通的。本文建立的轻骨料混凝土多轴强度准则,偏平面上的破坏包络线采用Wil-lam-Warnke模型在偏平面上的椭圆曲线,受拉和受压子午线采用二次抛物线形式,并利用四个参数来建立其方程。可以采用两种方法来确定这四个参数,并通过试验结果比较了这两种方法的优缺点。

Experimental results have revealed that lightweight aggregate （LWA） concrete undergoes platform flow plasticity when under high compressive stress. The ultimate strength surface of LWA concrete intersects with the hydrostatic stress axis at two different points, completely different from normal concrete for which the ultimate strength surface is open-ended. Strength criteria for normal concrete do not fit LWA concrete. In this paper, a four-parameter multi-axial strength criterion for LWA concrete is presented. The strength envelope of the proposed model in the deviatoric plane adopts an elliptic curve similar to that of Willam-Wamke model, and the tensile and compressive meridians are represented by quadratic functions with four parameters. Two methods can be used for the determination of the four parameters, and their merits and drawbacks are compared through analysis of experimental data.