Influence of non-persistent joint sets on the failure behaviour of concrete under uniaxial compression test

Abstract

Discrete element and experimental approaches were utilized for investigating the effects of non-persistent joint sets on the failure behaviour of concrete under uniaxial compressive test. concrete specimens (100 mmx120 mmx50 mm dimension) were prepared. Tensile strength of concrete was 1 MPa. Two sets of specimens consisting three and five joints were prepared. These joint have two different parallel and intersecting configurations. In samples consisting both of the parallel and intersecting configurations with three joints, the length of larger joint was 6 cm and the lengths of two small joints was 3 cm. In samples consisting both of the parallel and intersecting configurations with five joints, The length of two larger joints were 3 cm and the lengths of three small joints was 2 cm. When the notch number was 3, the angle of larger joints were changed from 0o to 90o by increasing the 30o. When the notch number was 5, the angle of smaller joints were changed from 0o to 90o by increasing the 30o. In intersectiong joint configurations, two joint sets were perpendiqular to eachother. Totally, 16 different models were tested under compression test. Cuncurrent with experimental tests, numerical simulation (Particle flow code in two dimension) were performed on the models comprising non-persistent joint sets. joints configurations were similar to experimental one. the results revealed that the failure procedure was governed mostly by both of the joint configuration. The specimens' compressive strengths were associated with the failure mechanism and fracture pattern of the discontinuities. Furthermore it was shown that the discontinuities' compressive behaviour is caused by the number of the induced tensile cracks incremented by decreasing the joint length. Only some AE hits exist in the initial phase of loading, then AE hits grow rapidly prior to reaching the peak applied stress. Moreover, every stress drop was convoyed by numerous AE hits. Finally, the failure strength and pattern are similar in both approaches of the experimental tests and the numerical simulation.