To be ready for the challenging conditions of the High Luminosity phase of the LHC accelerator at CERN, the ATLAS Inner Detector will be completely replaced with a new all-silicon Inner Tracker, the ITk. Sensors in the innermost layer will be exposed to a fluence up to 1.9$\cdot$10$^{16}$~n$_{eq}$/cm$^2$ (considering a safety factor of 1.5) at the half of the HL-LHC program, after which it is scheduled to be replaced together will the full innermost system. Pixel sensors with 3D technology have been chosen to instrument it due to their radiation hardness. Sensors with 25x100~$\mu$m$^2$ pixel pitch will be used in the central region of the innermost layer (barrel) while sensors with a pitch of 50x50~$\mu$m$^2$ will instrument its two side regions (end-caps). The Fondazione Bruno Kessler (FBK) has been chosen as one of the two vendors for the production of these sensors. This paper will present the performance of 3D pre-production sensors with both pixel pitches produced by FBK measured in test beams with devices irradiated up to and beyond the sensor end-of-life fluence.