Experimental Study Using Wedge-Splitting Test On Compact Tension Specimens

Wedge-splitting on compact tension specimen testing method is a technique which carries out fracture tests by adopting standard compact tension geometry configuration but wedge-splitting loading pattern in wedge splitting testing method. This new method has the advantages of two traditional methods, that is, wedge-splitting method and compact tension method. It not only may eliminate the influence of the additional moment caused by the non-collinear vertical forces on the true values of double-K fracture parameters, but also weaken the stiffness requires often needed for fracturing a specimen.Extensive studies had shown that the whole fracture behavior of concrete structures involves three stages, i.e. crack initiation, crack stable propagation and crack unstable propagation. The double-K fracture theory is considered to be a good description of such fracture behavior. In this theory, the present analytical solution to compute two fracture governing parameters well explains the potential mechanism resulted in the formation and development of fracture process zone from the level of the physical composite structures characteristics of concrete material. Therefore, it has been used as an instruction to make crack safety assessment for the practical engineering structures, especially for large-scale concrete high dam. And, it also has been viewed as a theoretical basis of "fracture toughness testing specification of hydro-engineering, China" drafted by electric ministry. For the aim of providing sufficient experimental data to support testing specification, having better understanding of size-effect on double-K fracture parameters together with further identifying the minimum specimen depth required for no size-effect double-K fracture parameters to make practical engineering application more convenient, a new testing approach, i.e., wedge-splitting test on compact tension specimen is attempted. A total of 36 specimens with different sizes of which the maximum size is 1250mm×1200mm×200mm are designed. Double-K fracture parameters are examined. After taking into account the contribution of tail curve of P-CMOD on fracture energy, the fracture energy of tested every specimen is calculated from the curve of P-CMOD. The measured critical crack tip opening displacement (CTOD_c) is compared with the calculated value, the relation between crack tip opening displacement and crack mouth opening displacement (CTOD-CMOD) is investigated.The results of the experimental research show that the used fracture testing method is easy and stable. Therefore, it is desired that this modified method can be regarded as a supplement...