Z shape joints under uniaxial compression

Abstract

In this paper, the effects of angle of Z shape non-persistent joint on the compressive behaviour of joint's bridge area under uniaxial compression load have been investigated. Furtheremore experimental test and Particle flow code in two dimension (PFC2D) have been used. concrete samples with dimension of 50 mmx50 mmx100 mm were prepared. Tensile strength of model material was 1 MPa. Within the specimen, three Z shape non-persistent notches were provided. The notch length was 1.5 cm. when two upper and lower notch have horizontal direction, the middle joint angle were 45o, 90o and 135o. When dips of two upper and lower notch was 90o, the middle joint angle were 45o, 90o and 135o degree. When dips of two upper and lower notch was 135 degree, the middle joint angle were 45o, 90o and 135o. Totally, 9 different configuration systems were prepared for Z shape non-persistent joints. Also, 37 models with different Z shape non-persistent notch angle were prepared in numerical model. The axial load with rate of 0.005 mm/s was applied to the model. Results indicated that the failure process was mostly governed by the Z shape non-persistent joint angle. The compressive strengths of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. In addition it was shown that the compresssive behaviour of discontinuities is depend on the number of the induced tensile cracks which are increased by increasing the middle joint angle. The middle joint has significant effect on the failure pattern. In fixed upper and lower joints angles, when the middle joint angle is 90o the failure stress has maximum value. On the other hand, it has minimum value when the middle joint angle was 135o. In fixed middle joint angle, the samples have minimum value when the upper and lower joints angles are 135o. At the end, the failure pattern and strength results of the experiential tests and the numerical simulations were similar.