In order to validate the 3D version of the 'Delft' lattice model a number of torsion tests was conducted on concrete cylinders. The cylinders were both notched and un-notched. A biaxial loading machine with rotational and vertical loading axes was…
In order to validate the 3D version of the 'Delft' lattice model a number of torsion tests was conducted on concrete cylinders. The cylinders were both notched and un-notched. A biaxial loading machine with rotational and vertical loading axes was used. Tests were conducted under different axial restraint. It was observed that a perturbation of the stress state induced by the torque may significantly affect the crack pattern. Under axial compressive stress, after a spiralling crack, an axial crack developed in un-notched specimens. In notched cylinders, the failure surface is conical if an axial load is present, while it appears flat and localized within the notch height in case no axial load is applied. In order to have a better insight in the fracture process, an impregnation technique is used for detecting the cracks at different stages of loading.